technetium-tc-99m-exametazime and Brain-Ischemia

To reliably identify patients at risk for symptomatic hemorrhagic transformation (SHT), future trials of thrombolysis for acute ischemic stroke might use a vascular imaging protocol applicable to a multicenter setting. The goal of this commentary is to address the safety of intravenous thrombolysis with the recombinant tissue plasminogen activator (rTPA) and potential solutions offered by single-photon emission CT (SPECT) as a noninvasive brain perfusion imaging modality.. Even if patients with severe stroke, extensive ischemic changes on CT scan, advanced age, and high blood pressure are excluded from thrombolytic therapy, this cannot completely guarantee the safety of using rTPA. Brain SPECT scanning with hexamethylpropyleneamine-oxime (HMPAO) may help to screen out patients at risk if performed in addition to clinical and CT tests. The knowledge of pretreatment severity, extent, and location of ischemia might identify good versus poor responders to rTPA therapy. HMPAO-SPECT is widely available and feasible to perform without delaying rTPA therapy. Rigorous quality control and use of reproducible visual and semiquantitative methods of interpreting SPECT are necessary for implementation of SPECT technology in multicenter clinical trials.. The major obstacle to general acceptance of thrombolytic therapies and rTPA in particular is the fear of symptomatic hemorrhagic transformation, and because HMPAO-SPECT might reliably identify patients at high risk of symptomatic hemorrhagic transformation, the clinical value of HMPAO-SPECT in patient selection for thrombolysis during the first hours of acute ischemic stroke should be determined through a prospective clinical trial.

Topics: Acute Disease; Brain; Brain Ischemia; Cerebrovascular Disorders; Humans; Nuclear Medicine; Organotechnetium Compounds; Oximes; Safety; Societies, Medical; Technetium Tc 99m Exametazime; Thrombolytic Therapy; Tomography, Emission-Computed, Single-Photon

Recent and future evolutions in neuroSPECT apply to radiopharmaceuticals techniques and the synergistic use of different imaging modalities in the work-up of neurological disorders. The introduction of Technetium labelled perfusion tracers, which could pass the intact blood-brain barrier, together with the implementation of the tomographic principle, by making the conventional gamma camera rotating, enabled estimation of regional cerebral blood flow and indirectly of local brain metabolism. In addition at present Thallium-201 and Tc-99m sestaMIBI allow functional detection of viable tumor tissue, without interference from previous surgery or radiotherapy as seen using CT-scan or MRI. In neurology this has led to the recognition of SPECT by the American Academy of Neurology (Therapeutics and technology subcommittee) as an established or promising tool in major neurological disorders such as dementia, stroke and epilepsy, while other domains such as brain oncology are considered investigational. With regard to radiopharmaceuticals, recent evolutions mainly include the development of mostly Iodine-123 labelled receptor ligands, some of which are already commercially available. For instrumentation advances consist e.g. of multidetector systems equipped with fanbeam collimators, attenuation and scatter correction or coincidence detection. Given the present role for nuclear neurology it may be expected that these additional radiopharmaceutical and technical innovations will continue to stimulate the development of SPECT of the brain. The synergistic use of several imaging techniques such as CT, (functional) MRI, source imaging, SPECT and PET represents a multimodal holistic approach to probe cerebral functions for research and clinical purposes. Clinical indications, in which this synergistic use is illustrated include e.g. support of the clinical diagnosis of dementia of the Alzheimer type, presurgical ictal detection of seizure focus, detection of acute ischemia and differential diagnosis between radiation necrosis and brain tumor recurrence. The synergistic use of imaging modalities, optimally applied using image fusion, allows to overcome the intrinsic limitations and to enhance the specific advantages of the different approaches as it leads to increased precision and accuracy, as well for spatial anatomofunctional correlation as for quantification.

Topics: Alzheimer Disease; Brain Ischemia; Brain Neoplasms; Epilepsy; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Mental Disorders; Nervous System Diseases; Neurology; Nitriles; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Thirty-two patients suffering from occlusive cerebrovascular disease were investigated by means of 99mTc-HMPAO brain SPECT before and one month after EC-IC bypass operation. The regional cerebral blood flow was unchanged postoperatively in 19 patients, increased in 7 cases, and deteriorated in 6 patients. One patient died in the postoperative period and in another no follow-up SPECT could be performed. It is concluded that the regional cerebral blood flow, even in the absence of a morphological deficit on CT, was not improved by the operation in the majority of cases.

Topics: Adult; Brain Ischemia; Cerebral Angiography; Cerebral Revascularization; Female; Follow-Up Studies; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Postoperative Period; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The efficacy of cerebral arterial bypass surgery was assessed on brain perfusion SPECT using statistical parametric mapping (SPM) and a probabilistic brain atlas.. Fifteen patients with ischemia in the internal carotid artery (ICA) territory and 21 age-matched healthy volunteers were enrolled. (99m)Tc-HMPAO basal/acetazolamide brain perfusion SPECT was performed 2 wk before and after bypass surgery and also on a healthy control group. Using SPM analysis, group comparisons were made between pre- and postoperative SPECT for each basal/acetazolamide image, and improvements of perfusion and perfusion reserve were assessed. The number of significant voxels on the SPM analysis was defined as the extent of ischemia. With the use of the probabilistic brain atlas, the counts for the cerebral lobes and the ICA territory were automatically calculated for each image and compared.. The group comparisons by SPM between patients and healthy volunteers showed a significant improvement in general perfusion status in the ICA territory. The improvement in perfusion reserve was more extensive than the improvement in perfusion. The extent of ischemia was also significantly decreased after surgery (1,693 +/- 2,604 to 371 +/- 523 voxels in basal images, P = 0.060; 11,879 +/- 6,449 to 5,997 +/- 3,864 voxels in acetazolamide images, P = 0.005). In the analysis using the probabilistic brain atlas, the preoperatively decreased perfusion was normalized after surgery, but a residual decrease in the perfusion reserve was also observed in the ICA territory. The counts in the volume of interest of the ICA territory were significantly improved (38.5 +/- 4.1 to 41.5 +/- 2.7 in basal images, P = 0.024; 34.2 +/- 4.4 to 38.8 +/- 2.9 in acetazolamide images, P = 0.003). One patient showing a decrease in perfusion had a perioperative cerebral infarct.. Using SPM and a probabilistic brain atlas, the perfusion, the perfusion reserve, and changes in both after cerebral arterial bypass surgery were effectively assessed and correlated well with physiologic reasoning.

Topics: Acetazolamide; Algorithms; Brain; Brain Ischemia; Brain Mapping; Case-Control Studies; Cerebral Revascularization; Computer Simulation; Female; Humans; Male; Middle Aged; Models, Statistical; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Hypoperfusion in the posterior cingulate cortex is thought to be useful for the early diagnosis of dementia of Alzheimer type (DAT). In the present study, we compared the incidence of posterior cingulate hypoperfusion in patients with Alzheimer's disease (AD), patients with senile dementia of Alzheimer type (SDAT), and patients with other types of dementia, as evaluated by three-dimensional stereotactic surface projection (3D-SSP) imaging. The subjects were 20 AD patients, 20 SDAT patients, 13 frontotemporal dementia patients, and 3 other types of dementia patients. A SPECT study was performed 5 minutes after the injection of 740 MBq technetium-99m hexamethylpropylene amine oxime. 3D-SSP images were obtained with global normalization to perform the statistical analysis. The normal database of 3D-SSP consisted of 15 healthy volunteers. Hypoperfusion was considered to be significant when the Z-score was over 2.5. Posterior cingulate hypoperfusion was observed in 13 of 20 AD patients (65%), in 5 of 20 SDAT patients (25%), but in none of other type of dementia patients. Posterior cingulate hypoperfusion was considered to be a finding specific to DAT, and this finding was thought to be useful to diagnose DAT patients, especially for AD patients. However, it was considered to be difficult to diagnose early-stage SDAT patients.

Topics: Aged; Alzheimer Disease; Brain Ischemia; Cerebrovascular Circulation; Dementia; Female; Gyrus Cinguli; Humans; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Male; Middle Aged; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Severity of Illness Index; Statistics as Topic; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

We used 99mTc-hexamethylpropyleneamine oxime single-photon emission computed tomography (SPECT) to study cerebral perfusion in patients treated with streptokinase for acute ischemic stroke in an open and prospective study. Our primary aims were (1) to compare the extent of reperfusion between patients who had received thrombolytic therapy and a control group studied during the same period who were ineligible to receive such therapy and (2) to determine if, among all patients, reperfusion led to improved outcome.. Fifty-seven patients (22 treated with streptokinase) had two SPECT studies performed, the first before streptokinase administration and the second 24 hours later.. On the first SPECT study hyperfusion was present in the middle cerebral artery or anterior cerebral artery territories in 40 patients (17 treated with streptokinase). Patients in the treatment and control groups with initial hypoperfusion on SPECT were well matched for the volume of the perfusion defect and the severity of neurological deficit. A greater number of patients who received streptokinase developed at least partial reperfusion (streptokinase, 65%; control, 52%) on the second study but not significantly so (P = .43). Similarly, the proportion of each hypoperfused region that reperfused (P = .74) and the reduction in the size of the perfusion defect (P = .06) were higher in the streptokinase group but did not reach statistical significance. When all patients were considered, those who did not reperfuse had higher mortality rates (P = .008), less neurological improvement (P = .016), and more functional disability (P < .001) than patients who had reperfusion or normal perfusion initially.. These findings suggest that at least some reperfusion during the first 48 hours of ischemic stroke is a common natural occurrence and is of prognostic significance. The observed trend toward better reperfusion indexes among patients treated with streptokinase is encouraging, but larger controlled trials are required to answer this definitively.

Topics: Aged; Brain Ischemia; Cerebral Angiography; Cerebrovascular Disorders; Female; Humans; Male; Nervous System; Organotechnetium Compounds; Oximes; Pilot Projects; Reperfusion; Streptokinase; Subtraction Technique; Survival Analysis; Technetium Tc 99m Exametazime; Thrombolytic Therapy; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

Thrombolytic therapy was carried out on patients with acute ischemic stroke, and the risk of hemorrhagic transformation was evaluated from the residual cerebral blood flow (CBF) by pretherapeutic single-photon emission-computed tomography (SPECT).. Local intra-arterial thrombolytic therapy was carried out using urokinase or recombinant tissue plasminogen activator (rt-PA) within 6 hours from the onset in 34 patients in whom no hypodensity areas were observed on the initial computed tomography examination. In the 20 patients with carotid territory occlusion who underwent 99mTc-labeled hexamethylpropyleneamine oxime (99mTc-HMPAO) SPECT, the residual CBF of the ischemic region was evaluated semiquantitatively by calculating two parameters: the ischemic regional activity to cerebellar activity ratio (R/CE ratio) and asymmetry index (AI).. The occluded vessels could be recanalized in 22 (92%) of the 24 patients in the urokinase group and in all 10 of the patients in the rt-PA group. Hemorrhagic transformation appeared in 4 patients in the urokinase group and 3 patients in the rt-PA group. Among the 20 patients who underwent SPECT before the treatment, the residual CBF was lower in the 5 patients who developed hemorrhagic transformation than in the 15 who did not (P < .05). Hemorrhagic transformation occurred in all patients with R/CE ratio of less than 0.35 and AI of more than 1.5.. The risk of hemorrhagic transformation after recanalization of occluded vessels by local intra-arterial thrombolytic therapy was considered to be high when the pretherapeutic residual CBF was markedly reduced.

Topics: Acute Disease; Adult; Aged; Aged, 80 and over; Brain Ischemia; Cerebral Hemorrhage; Cerebrovascular Circulation; Female; Follow-Up Studies; Humans; Infusions, Intra-Arterial; Male; Middle Aged; Neurologic Examination; Organotechnetium Compounds; Oximes; Recombinant Proteins; Risk Factors; Technetium Tc 99m Exametazime; Thrombolytic Therapy; Tissue Plasminogen Activator; Tomography, Emission-Computed, Single-Photon; Urokinase-Type Plasminogen Activator

Cerebral ischemia is a leading cause of disability worldwide and no other effective therapy has been validated to date than intravenous thrombolysis. In this context, many preclinical models have been developed and recent advances in preclinical imaging represent promising tools. Thus, we proposed here to characterize in vivo time profiles of cerebral blood flow, blood-brain barrier disruption and apoptosis following a transient middle cerebral artery occlusion in rats using SPECT/CT imaging.. Rats underwent a 1-h middle cerebral artery occlusion followed by reperfusion. Cerebral blood flow, blood-brain barrier disruption and apoptosis were evaluated by SPECT/CT imaging using respectively (99m)Tc-HMPAO, (99m)Tc-DTPA and the experimental (99m)Tc-Annexin V-128, up to 14 days after middle cerebral artery occlusion. Histological evaluation of apoptosis has been performed using TUNEL method to validate the (99m)Tc-Annexin V-128 uptake.. (99m)Tc-HMPAO cerebral blood flow evaluation showed hypoperfusion during occlusion, partially restored on days 4 and 7 and sustained up to 14 days after middle cerebral artery occlusion. (99m)Tc-DTPA SPECT/CT showed a blood-brain barrier disruption starting on day 1 post-middle cerebral artery occlusion, peaking on day 2, with barrier integrity totally restored on day 7. (99m)Tc-Annexin V-128 SPECT/CT imaging showed significant positive correlation with TUNEL immunohistochemistry and allowed ischemic-induced apoptosis to be detected from day 2 to day 7, peaking on day 3 after middle cerebral artery occlusion.. Using SPECT/CT imaging, we showed that after transient middle cerebral artery occlusion in rat there was a sustained decrease in cerebral blood flow followed by blood-brain barrier disruption preceding meanwhile apoptosis. Rodent SPECT/CT imaging of cerebral blood flow, blood-brain barrier disruption and apoptosis appears to be an efficient tool for evaluating neuroprotective drugs and regenerative therapies against cerebral ischemia and time-windows for therapeutic intervention.

Topics: Animals; Apoptosis; Blood-Brain Barrier; Brain; Brain Ischemia; Cerebrovascular Circulation; Disease Models, Animal; Disease Progression; In Situ Nick-End Labeling; Infarction, Middle Cerebral Artery; Male; Multimodal Imaging; Pentetic Acid; Radiopharmaceuticals; Rats, Sprague-Dawley; Technetium Tc 99m Exametazime; Time; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Strategies to promote angiogenesis can benefit cerebral ischemia. We determined whether liposomal delivery of angiogenic peptides with a known biologic activity of vascular endothelial growth factor benefitted cerebral ischemia. Also, the study examined the potential of (18)F-FDG PET imaging in ischemic stroke treatment.. Male Sprague-Dawley rats (n = 40) underwent 40 min of middle cerebral artery occlusion. After 15 min of reperfusion, the rats (n = 10) received angiogenic peptides incorporated into liposomes. Animals receiving phosphate-buffered solution or liposomes without peptides served as controls. One week later, (18)F-FDG PET imaging was performed to examine regional changes in glucose utilization in response to the angiogenic therapy. The following day, (99m)Tc-hexamethylpropyleneamine oxime autoradiography was performed to determine changes in cerebral perfusion after angiogenic therapy. Corresponding changes in angiogenic markers, including von Willebrand factor and angiopoietin-1 and -2, were determined by immunostaining and polymerase chain reaction analysis, respectively.. A 40-min period of middle cerebral artery occlusion decreased blood perfusion in the ipsilateral ischemic cortex of the brain, compared with that in the contralateral cortex, as measured by (99m)Tc-hexamethylpropyleneamine oxime autoradiography. Liposomal delivery of angiogenic peptides to the ischemic hemisphere of the brain attenuated the cerebral perfusion defect compared with controls. Similarly, vascular density evidenced by von Willebrand factor-positive staining was increased in response to angiogenic therapy, compared with that of controls. This increase was accompanied by an early increase in angiopoietin-2 expression, a gene participating in angiogenesis. (18)F-FDG PET imaging measured at 7 d after treatment revealed that liposomal delivery of angiogenic peptides facilitated glucose utilization in the ipsilateral ischemic cortex of the brain, compared with that in the controls. Furthermore, the change in regional glucose utilization was correlated with the extent of improvement in cerebral perfusion (r = 0.742, P = 0.035).. Liposomal delivery of angiogenic peptides benefits cerebral ischemia. (18)F-FDG PET imaging holds promise as an indicator of the effectiveness of angiogenic therapy in cerebral ischemia.

Topics: Animals; Brain; Brain Ischemia; Cerebrovascular Circulation; Drug Delivery Systems; Fluorodeoxyglucose F18; Glucose; Ischemia; Liposomes; Male; Multimodal Imaging; Neovascularization, Pathologic; Peptides; Perfusion; Positron-Emission Tomography; Rats; Rats, Sprague-Dawley; Stroke; Technetium; Technetium Tc 99m Exametazime; Tomography, X-Ray Computed

To determine whether severe cerebral perfusion defects measured by SPECT prior to rt-PA therapy attribute to severe intracerebral hemorrhage (SICH).. We measured baseline cerebral blood flow (CBF) using technetium-99m-labeled hexamethylpropyleneamine oxime (99mTc-HMPAO) SPECT qualitatively prior to rt-PA therapy, in 52 consecutive patients (range 38-93 years). The degree and extent of the asymmetry of local CBF were analyzed semi-quantitatively. We did not administrate rt-PA in patients with severe perfusion defects. Clinical outcome and the incidence of SICH were studied.. Three (5.8%) patients had severe perfusion defects that were undetected by CT and/or DWI. The other 49 (94.2%) patients had mild perfusion defects. The asymmetry of local CBF was 0.08±0.08 (n=3) and 0.3±0.15 (n=49) in the two groups, respectively. The percentages of the ipsilateral hemisphere in which perfusion was impaired severely were 17.5±9.5% (n=3) and 0.43±0.87% (n=49). Two patients were found petechial hemorrhage, but there was no patient who developed SICH in the former group following conventional antithrombotic therapy. In the latter group, SICH occurred in 1/49 (2.0%) patient following rt-PA therapy.. These results suggest that rt-PA therapy for patients with severe cerebral perfusion defects may cause SICH and baseline CBF may contribute to identify patients at high risk for SICH after intravenous rt-PA therapy.

Topics: Aged; Aged, 80 and over; Antifibrinolytic Agents; Brain; Brain Ischemia; Cerebrovascular Circulation; Female; Functional Laterality; Humans; Injections, Intravenous; Male; Middle Aged; Neurologic Examination; Radiopharmaceuticals; Stroke; Technetium Tc 99m Exametazime; Tissue Plasminogen Activator; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

Arterial spin labelling (ASL) is increasingly available for noninvasive cerebral blood flow (CBF) measurement in stroke research. Here, a pseudo-continuous ASL technique (pCASL) was evaluated against (99m)Tc-D, L-hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) autoradiography in a rat stroke model. The (99m)Tc-HMPAO was injected (intravenously, 225 MBq) during pCASL acquisition. The pCASL and (99m)Tc-HMPAO autoradiography CBF measures, relative to the contralateral hemisphere, were in good agreement across the spectrum of flow values in normal and ischemic tissues. The pCASL-derived quantitative regional CBF values (contralateral: 157 to 177 mL/100 g per minute; ipsilateral: 9 to 104 mL/100 g per minute) were consistent with the literature values. The data show the potential utility of pCASL for CBF assessment in a rat stroke model.

Topics: Animals; Brain Ischemia; Cerebrovascular Circulation; Disease Models, Animal; Magnetic Resonance Angiography; Radiography; Radiopharmaceuticals; Rats; Rats, Sprague-Dawley; Spin Labels; Stroke; Technetium Tc 99m Exametazime

In this study, we validated the use of (99m)Tc-hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) micro-SPECT combined with micro-CT for semiquantification of the infarct size after an experimental stroke in rats and compared our observations with those obtained from histology. This imaging strategy was applied to measure the longitudinal effect of mild hypothermia on the progression of brain damage after stroke in rats.. The endothelin-1 model was used to elicit a transient focal cerebral ischemia in rats. This resulted in a reproducible insult in which the core is represented by the striatum and the penumbra by the cortex. Micro-SPECT and micro-CT images were taken at 1, 3, and 7 d after infusion of endothelin-1 and compared with those taken before the insult. After the last acquisition, rats were sacrificed and the infarct volume was determined via Nissl staining. The results obtained with micro-SPECT and micro-CT were compared with histology at the same time points. Mild hypothermia (33°C) was induced for 2 h, starting 20 min after the insult.. Brain damage was estimated using micro-SPECT and micro-CT and was reproducible with minimal interobserver variability. Normothermic stroke rats had reduced (99m)Tc-HMPAO uptake at 1 and 3 d after the insult, whereas hypothermia improved damage after stroke. These findings corroborate with histology at the same time points. At 1 wk after the insult, no reduction of radioactive uptake was observed in any treatment group.. Micro-SPECT and micro-CT allow quick and reproducible semiquantification of brain damage as an interesting alternative to histology to measure the extent of infarcted tissue in small animals after stroke.

Topics: Animals; Brain Ischemia; Endothelin-1; Hypothermia, Induced; Male; Rats; Rats, Wistar; Reproducibility of Results; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; X-Ray Microtomography

Recently, small semiconductor gamma cameras (SSGCs) with high resolution and sensitivity, which are much more convenient to use as compared with SPECT and PET, have been developed for mapping the sentinel lymph node. The high resolution and sensitivity of the SSGCs may make them useful for small animal imaging. Therefore, we assessed the applicability of the SSGC to small animal imaging using a rat model of focal cerebral ischaemia.. The right middle cerebral artery (MCA) of anaesthetized rats was occluded intraluminally with a nylon monofilament. Twenty-four hours after the occlusion, 99mTc-HMPAO (3.7 MBq) was injected and a static acquisition (5 min) was performed using the SSGC. Regions of interest (ROIs) were set on each hemisphere of the horizontal brain images. After the acquisition, the brains were removed and the radioactivity in each hemisphere was measured using an NaI scintillation counter.. Reduced CBF in the right MCA territory was clearly visualized with the SSGC in vivo. The radioactivity in the ROIs determined by the SSGC was significantly correlated with that determined by the ex vivo counting method (P<0.001, R2=0.74). Furthermore, in both of the in-vivo imaging and ex-vivo counting methods, the right to left count ratio (R/L ratio) was significantly lower in the MCA-occluded rats than that in normal rats (MCA-occluded rats: 0.77+/-0.08, normal rats: 1.01+/-0.07, P<0.005).. The SSGC clearly visualized and quantitatively detected the reduced CBF in MCA-occluded rats. Furthermore, these high resolution and sensitivity of SSGC can avoid the disadvantage of small animal imaging with PET and SPECT, such as a large mass injected tracer and the exposure of investigators to radiation. Thus, the high resolution and sensitivity of the SSGC make it useful for small animal imaging.

Topics: Animals; Brain Ischemia; Dose-Response Relationship, Radiation; Equipment Design; Gamma Cameras; Image Processing, Computer-Assisted; Male; Middle Cerebral Artery; Phantoms, Imaging; Radiopharmaceuticals; Rats; Rats, Wistar; Semiconductors; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

To assess the effect of unilateral carotid angioplasty and stenting (CAS) on cerebral perfusion asymmetry in patients with severe extracranial carotid stenosis by means of technetium Tc 99m hexamethyl-propyleneamine oxime brain single photon emission computed tomography ((99m)Tc-HMPAO SPECT).. Twenty-nine consecutive patients (22 men; median age 68 years, range 58-80; 13 symptomatic) undergoing unilateral CAS were included in the study. Brain perfusion was assessed by (99m)Tc-HMPAO brain SPECT prior to the procedure and postoperatively at 8 hours and at 2 to 4 months. The asymmetry index (AI), a measure of the interhemispheric asymmetry in perfusion, was calculated as [(counts in "healthy" hemisphere-counts in hemisphere with carotid stenosis)/counts in "healthy" hemisphere]x100.. The preoperative AI demonstrated a wide variation (mean -0.5%+/-8.4%, range -19.5% to 14.1%). There was no significant correlation between the degree of carotid stenosis and preoperative AI. The mean preoperative AI in the asymptomatic patients was lower than in the symptomatic group [-4.0%+/-8.5% (range -19.5% to 8.2%) versus 3.8%+/-6.4% (range -5.2% to 14.1%), p=0.01], suggesting reduced perfusion of the ipsilateral cerebral hemisphere compared to the contralateral side in symptomatic patients. AI variation did not improve after CAS; there was no difference in AI among the 3 SPECT studies (p=0.75). Preoperative AI correlated significantly with late AI (r=0.74, p<0.0001); however, there was no statistically significant correlation between immediate postoperative AI and either preoperative (r=0.24, p=0.217) or late (r=0.24, p=0.249) AI.. Asymmetry in cerebral perfusion in patients with severe extracranial carotid atherosclerosis does not correlate with the degree of carotid stenosis. Symptomatic patients demonstrate compromised perfusion of the ipsilateral hemisphere compared to asymptomatic patients. As judged by (99m)Tc-HMPAO SPECT scanning, cerebral perfusion patterns do not significantly change after CAS.

Topics: Aged; Aged, 80 and over; Amaurosis Fugax; Angiography, Digital Subtraction; Angioplasty, Balloon; Blood Vessel Prosthesis Implantation; Brain Ischemia; Carotid Stenosis; Cerebrovascular Circulation; Female; Follow-Up Studies; Humans; Ischemic Attack, Transient; Linear Models; Magnetic Resonance Imaging; Male; Middle Aged; Radiopharmaceuticals; Severity of Illness Index; Stents; Stroke; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

Measuring blood pressure (stump pressure) in the distal internal carotid artery during occlusion of the internal carotid artery is reportedly a reliable safety index with which to predict ischemia following permanent occlusion of the internal carotid artery. We compared the stump pressure during occlusion of the internal carotid artery with single-photon emission CT (SPECT) using technetium Tc 99m hexamethylpropyleneamine oxime (HMPAO).. Twenty-seven patients underwent the balloon occlusion test. After occlusion of the internal carotid artery was performed by a balloon catheter, technetium Tc 99m HMPAO was injected, and then the balloon remained inflated for 15 minutes. The stump pressure was continuously monitored for those 15 minutes. After the balloon catheter was deflated and removed, SPECT was performed. Sixty-four symmetric pairs of regions of interest were set on both sides of the cerebral hemisphere. The radioactivity count ratio (L/n ratio) of the occluded side to the contralateral normal side was calculated. We defined hypoperfusion as an area with an L/n ratio <0.8. The minimum mean stump pressure (minMSP) during the balloon occlusion test and the pressure ratio of the minMSP to the mean systemic pressure were compared with the hypoperfusion area on SPECT.. The number of regions of interest with hypoperfusion was significantly (P < .001) greater in patients with a minMSP <40 mm Hg (mean [+/-SD] = 31.5 +/- 13.7) than in patients with a minMSP > or =40 mm Hg (5.1 +/- 4.0). The number of regions of interest with hypoperfusion was also significantly (P < .001) greater in patients with a pressure ratio <0.5 (26.7 +/- 15.8) than in patients with a pressure ratio > or =0.5 (4.5 +/- 3.5).. The minMSP during the balloon test occlusion reflects the extent of the hypoperfused area measured by SPECT using technetium Tc 99m HMPAO.

Topics: Adult; Aged; Balloon Occlusion; Blood Pressure; Brain Ischemia; Carotid Artery, Internal; Female; Humans; Male; Middle Aged; Predictive Value of Tests; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The current clinical practice of reporting images obtained with single photon emission computed tomography (SPECT) with 99mTc-d,l-hexamethylpropylene amine oxime (99mTc HMPAO) images was examined by having 16 experts evaluate the appearance of SPECT images in patients with probable Alzheimer type dementia (ATD), patients with major depressive episode (DSM-IV), and healthy volunteers. The experts rated diagnostic criteria of scan appearance in respect of importance for their individual diagnostic practice. Experts were nuclear medicine specialists, psychiatrists and physicists taking part in a European multi-centre collaborative project. They examined 158 perfusion scans and then the same perfusion scans together with statistical parametric maps (SPMs). The sensitivity of experts' diagnostic judgments was significantly and negatively correlated with the importance they attributed to reduced regional perfusion in the parietal lobes. A corresponding positive correlation was observed for diagnostic specificity against depressed and healthy volunteers. Similar results were observed with SPMs, where in addition area under the receiver operating characteristic (ROC) curve was significantly reduced with raters' increased diagnostic reliance on frontal lobe perfusion deficits. Sensitivity was greater with SPM for patients younger than 70 years and with dementia severity. The more importance experts placed on parietal (symmetrical) perfusion deficits, the less sensitive and the more specific their diagnostic judgment was. Using multiple raters in large patient samples may provide a way of identifying successful explicit diagnostic strategies for clinical image analysis.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Atrophy; Brain; Brain Ischemia; Cerebral Cortex; Depressive Disorder, Major; Diagnosis, Differential; Dominance, Cerebral; Female; Humans; Image Processing, Computer-Assisted; Male; Mental Status Schedule; Middle Aged; Parietal Lobe; Personality Inventory; ROC Curve; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Four hours after having taken 10 ecstasy tablets a Grand Mal seizure occurred in a 19-year-old woman followed by coma, hyperthermia, tachycardia, tachypnea, and renal failure. After awakening she was oriented but presented with helplessness, disconcertion, hallucinations, panic attacks, and amnesic syndrome. Computed tomography and magnetic resonance imaging scans of the brain were normal. [99Tc]-hexamethylpropyleneamine oxime (HMPAO)-single photon emission computed tomography (SPECT), 20 days after intoxication, showed reduced, inhomogeneous, supratentorial tracer uptake bilaterally. Electroencephalography (EEG) disclosed diffuse slowing and occasionally generalized sharp waves. Valproic acid was begun. Except for slight amnesia, neuropsychological deficits had disappeared and [99Tc]-HMPAO-SPECT normalized, 29 days later. Decreased cortical blood flow was explained by vasoconstriction following ecstasy-induced depletion of serotonin.

Topics: Adult; Brain Ischemia; Cerebral Cortex; Coma; Dominance, Cerebral; Drug Overdose; Electroencephalography; Epilepsy, Tonic-Clonic; Female; Follow-Up Studies; Humans; N-Methyl-3,4-methylenedioxyamphetamine; Neuropsychological Tests; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Vasoconstriction

Technetium-99m hexamethylpropylene amine oxime (HMPAO) and (99m)Tc- N, N"-1,2-ethylene diylbis- l-cysteine diethyl ester dihydrochloride (ECD) yield significantly different images of cerebral perfusion owing to their particular pharmacokinetics. The aim of this study was to assess the topography, extension and statistical significance of these differences in Alzheimer's disease (AD). Sixty-four patients with mild to moderate AD were retrospectively selected by two European centres. Two series of patients, including 32 studied with (99m)Tc-HMPAO single-photon emission tomography (SPET) and 32 studied with (99m)Tc-ECD SPET, were matched for sex, age (+/-3 years) and severity of cognitive impairment as assessed by the Mini-Mental State Examination (MMSE) (+/-2 points), following a case-control procedure. SPET data were processed using SPM99 software (uncorrected height threshold: P=0.001). (99m)Tc-ECD SPET gave significantly higher uptake ratio values than (99m)Tc-HMPAO SPET in several symmetrical clusters, including the right and left occipital cuneus, the left occipital and parietal precuneus, and the left superior and middle temporal gyri. (99m)Tc-HMPAO SPET gave significantly higher uptake ratio values than ECD in two smaller clusters, including the hippocampus in both hemispheres. In AD, relative brain uptake of (99m)Tc-HMPAO and (99m)Tc-ECD is different in several brain regions, some of which are typically involved in AD, such as the precuneus and the hippocampus. These differences confirm the need for specific normal databases, but their impact on routine SPET reports in AD is not known and deserves an ad hoc investigation.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Brain; Brain Ischemia; Case-Control Studies; Cysteine; Female; Humans; Male; Organotechnetium Compounds; Radionuclide Imaging; Radiopharmaceuticals; Reproducibility of Results; Retrospective Studies; Sensitivity and Specificity; Technetium Tc 99m Exametazime

To evaluate the feasibility of utilizing cerebral blood flow (CBF) index images, we attempted to investigate 1) whether CBF index images can reveal the resulting infracted area, 2) whether the CBF index can correlate other modality (SPECT).. DWI and DPI were obtained in 17 patients within 12 hours of stroke onset and follow up MRI. On three DPI delivered images, namely relative regional cerebral blood volume (rrCBV), uncorrected mean transit time (MTTu) and CBF index images, correlations between initial lesion volume of and follow up infarction volume of three images and rCBF images delivered with singular value decomposition (SVD) methods were assessed. Then 99mTc-ECD SPECT was taken immediately after MRI to correlate to MRI data.. Among the three images, lesion volume of CBF index images against follow up infarct volume had the highest correlation (r = 0.995) to a linear fit and the slope was closest to 1.0 (0.91) and had identical accuracy to the regression coefficient of rCBF images. CBF index well correlated to SPECT delivered CBF.. CBF index images can accurately predict final infarct volume. Evaluating CBF index images together with DWI can guide the initial assessment in the acute stage of cerebral ischemia.

Topics: Acute Disease; Brain; Brain Ischemia; Cerebral Infarction; Cerebrovascular Circulation; Diffusion Magnetic Resonance Imaging; Echo-Planar Imaging; Humans; Magnetic Resonance Angiography; Prognosis; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

To investigate the relationship between relative cerebral blood volume (CBV) measured with perfusion-weighted (PW) MR imaging and relative cerebral blood flow (CBF) measured with SPECT in acute ischemic stroke.. Fifteen patients who had acute unilateral middle cerebral artery occlusion underwent both PW MR imaging and 99mTc-HMPAO SPECT with an interval less than 20 min between the two examinations within 6 h after stroke onset. Lesion-to-contralateral relative CBV and CBF ratios measured in multiple regions of interest were compared to evaluate the relationship of the two parameters.. An overall linear relationship was found between relative CBV and relative CBF ratios (R2 = 0.54, p < 0.0001). The two parameters correlated linearly to each other in regions with evolving infarction (R2 = 0.43, p<0.0001), but not in regions without evolving infarction (R2 = 0.001, p>0.05). Regions with evolving infarction had more severe hypoperfusion (mean relative CBF ratio, 0.38 +/- 0.22) than regions without (mean relative CBF ratio, 0.70+/-0.13) (p<0.0001).. A significant linear relationship existed between relative CBV and relative CBF in acute ischemic stroke, although relative CBV did not change linearly to relative CBF in mild hypoperfusion. Relative CBV can be used as an alternative to relative CBF within 6 h after stroke onset, particularly in regions with severe hypoperfusion proceeding to infarction.

Topics: Brain; Brain Ischemia; Case-Control Studies; Cerebrovascular Circulation; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Radiopharmaceuticals; Retrospective Studies; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Postictal psychosis is a rare complication of epileptic seizure characterized by reversible psychotic symptoms after flurries of seizure attack. It has been attributed to a phenomenon similar to Todd's paralysis without definitive proof. We studied regional cerebral blood flow (rCBF) of six patients with postictal psychosis by (99m)Tc-HMPAO SPECT scan. Baseline rCBF was compared with the rCBF during postictal psychosis. An asymmetry index (ASI) was calculated as 200 x [(ipsilateral ROI count density - contralateral ROI count density)/(ipsilateral ROI count density + contralateral ROI count density)] %. Significant differences could be found between ASIs during postictal psychosis and interictal state SPECT scan over the lateral temporal neocortex region (P = 0.017). Although hyperperfusion abnormality in SPECT can be found in Todd's paralysis, such findings are more commonly found in cerebral hyperactivity conditions. Taking into account the clinical characteristics of postictal psychosis, namely a preceding lucid interval and crescendo-decrescendo clinical course, these may be an alternative psychopathogenic mechanism for the development of postictal psychosis.

Topics: Adolescent; Adult; Brain Ischemia; Dominance, Cerebral; Electroencephalography; Evoked Potentials; Female; Humans; Image Processing, Computer-Assisted; Male; Middle Aged; Neurocognitive Disorders; Regional Blood Flow; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed, Single-Photon

To test the hypothesis that syndrome X is a systemic vascular disorder, the authors studied 40 patients with this diagnosis using technetium-99m hexamethylpropylene amine oxime and single photon emission computed tomography (SPECT) brain images. Twenty-three of 25 cases with definite myocardial perfusion defects diagnosed by thallium-201 myocardial perfusion SPECT also had multiple hypoperfusion areas in the brain versus 2 of 15 patients without thallium myocardial defects. The parietal lobes were the most common hypoperfusion areas, and cerebellum was the least common. Syndrome X is a systemic vascular disorder with a high incidence of hypoperfusion lesions of the brain and is usually coincident with myocardial defects.

Topics: Adult; Basal Ganglia; Brain; Brain Ischemia; Cerebellum; Cerebral Cortex; Female; Humans; Male; Microvascular Angina; Middle Aged; Regional Blood Flow; Technetium Tc 99m Exametazime; Thalamus; Thallium Radioisotopes; Tomography, Emission-Computed, Single-Photon

Baseline regional cerebral blood flow of thirty unmedicated late-onset unipolar major depressed patients over the age of 60 years and 20 sex-, age-, and vascular risk factor-matched healthy controls was imaged with single photon emission computed tomography, using technetium-99m hexamethylpropylene amine oxime as a tracer. To avoid errors of diagnosis--in particular, confusion between major depression and organic cognitive impairment--only treatment responders were included in the final sample. Statistically significant differences were observed in both left and right anterior frontal regions, with reduced uptake in depressed patients; these differences were more pronounced in the left hemisphere. Among patients, there was no correlation between regional cerebral blood flow and the severity of baseline symptoms. Our results support the hypothesis that certain neuroanatomic regions of the central nervous system may be functionally involved in elderly unipolar major depression, particularly in the late-onset subgroup.

Topics: Aged; Brain Ischemia; Depressive Disorder, Major; Dominance, Cerebral; Female; Frontal Lobe; Humans; Image Processing, Computer-Assisted; Male; Middle Aged; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Intraarterial thrombolytic therapy has been used recently for treatment of acute ischemic stroke within 6 h after onset. Although hypoactivity of 99mTc-hexamethylpropyleneamine oxime (HMPAO) in stroke has been well documented, hyperactivity of HMPAO has not been evaluated in sufficient detail. The purpose of this study was to evaluate the incidence and clinical importance of hyperactivity of HMPAO in management of patients with acute ischemic stroke.. We retrospectively investigated HMPAO SPECT in 90 patients with acute ischemic stroke within 6 h after onset. The lesion-to-contralateral radioactivity ratios (L/Cs) were calculated on the SPECT images before treatment and were compared with the imaging results of CT or MRI (or both).. Hyperactivity of HMPAO, accompanied by surrounding hypoactivity, was observed in 6 of 90 patients (7%) within 6 h after onset. The L/Cs ranged from 1.17 to 2.95. Two patients showed hyperactivity in the cortex and the other 4 patients showed hyperactivity in the basal ganglia. Angiography confirmed spontaneous recanalization of occluded vessels in accordance with the area of hyperactivity. In both patients with cortical hyperactivity, cerebral infarctions were revealed on follow-up CT; in 1 patient, hemorrhagic transformation developed after intraarterial thrombolytic therapy. In 3 of the 4 patients with hyperactivity in the basal ganglia, follow-up CT showed no infarction in the surrounding hypoperfused cortex (selective intraarterial thrombolytic therapy was performed on 2 patients), although various degrees of infarction were observed in the basal ganglia. Obvious infarctions developed in the basal ganglia and the cortex of the other patient.. Hyperactivity of HMPAO could be seen in the basal ganglia and the cortex within 6 h after onset, reflecting spontaneous recanalization. The areas of hyperactivity may develop infarctions, whereas the accompanying areas of hypoactivity could be rescued by selective intraarterial thrombolytic therapy.

Topics: Acute Disease; Adult; Aged; Aged, 80 and over; Brain Ischemia; Cerebral Angiography; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Radiopharmaceuticals; Retrospective Studies; Stroke; Technetium Tc 99m Exametazime; Thrombolytic Therapy; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Three children with middle fossa arachnoid cysts, presenting with non-specific symptoms and otherwise well, were investigated before and after surgery with magnetic resonance and 99Tc-hexamethylpropyleneamineoxime single photon emission computerised tomography scans, to assess the effect of the cysts on cerebral blood flow. All patients had evidence of a reduction in cerebral blood flow at presentation, even in the hemisphere contralateral to the middle fossa cyst, implied by perfusion defects seen centrally in the deep white matter of both cerebral hemispheres. After successful surgical excision of the cyst, the perfusion defects disappeared. This was associated with general improvement of pre-existing non-specific symptoms. These findings indicate that middle fossa arachnoid cysts may cause global impairment of brain function by interfering with its blood supply. This does not support the generally held view that such cysts are benign in nature when 'asymptomatic'.

Topics: Adolescent; Arachnoid Cysts; Brain Ischemia; Child, Preschool; Dominance, Cerebral; Humans; Magnetic Resonance Imaging; Male; Postoperative Complications; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Early recanalisation by thrombolysis is a conclusive therapy for acute ischaemic stroke. But this therapy may increase the risk of intracerebral haemorrhage or severe brain oedema. The purpose was to evaluate usefulness of quantitative measurement of cerebral blood flow by single photon emission computed tomography (SPECT) in predicting the risk of haemorrhage or oedema, and determining the therapeutic options in acute hemispheric ischaemic stroke.. The relation was studied retrospectively between initial regional cerebral blood flow (rCBF) quantitatively measured by technetium-99m-labelled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) SPECT and final clinical and radiological outcome in 20 patients who presented hemispheric ischaemic stroke and were treated conservatively or received early recanalisation by local intra-arterial thrombolysis. The non-invasive Patlak plot method was used for quantitative measurement of rCBF by SPECT.. Regions where residual rCBF was preserved over 35 ml/100 g/min had a low possibility of infarction without recanalisation and regions where residual rCBF was preserved over 25 ml/100 g/min could be recovered by early recanalisation. However, regions where residual rCBF was severely decreased (< 20 ml/100 g/min) had a risk of intracerebral haemorrhage and severe oedema.. A quantitative assessment of residual rCBF by (99m)Tc-HMPAO SPECT is useful in predicting the risk of haemorrhage or severe oedema in acute ischaemic stroke. Therapeutic options should be determined based on the results of rCBF measurement.

Topics: Acute Disease; Aged; Aged, 80 and over; Brain Ischemia; Cerebrovascular Circulation; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Prognosis; Stroke; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Various clinical subtypes of patients presenting with sudden-onset ischemic stroke have been recognized, but classification of those types is not simple. We identified various patterns of perfusion-weighted MR imaging and MR angiographic findings in hyperacute ischemic stroke with relation to clinical outcomes.. Twelve patients with symptoms of acute ischemic stroke due to middle cerebral artery occlusion underwent perfusion-weighted MR imaging and MR angiography within 6 hours after the onset of symptoms. Perfusion-weighted imaging was performed with a conventional dynamic contrast-enhanced T2*-weighted sequence, and cerebral blood volume (CBV) maps were then created. CBV maps and MR angiographic findings were compared with 99mTc-HMPAO brain SPECT scans, short-term outcomes, and follow-up imaging findings.. The combined CBV and MR angiographic findings were classified into three patterns: arterial occlusion and decreased CBV (n = 8), arterial occlusion and increased CBV (n = 2), and no arterial occlusion and normal CBV (n = 2). These three patterns were strongly related to SPECT findings, short-term outcomes, and follow-up imaging findings. Perfusion on SPECT decreased markedly in the affected regions in all patients with the first pattern, decreased slightly in the second pattern, and was normal in the third pattern. Symptoms were not significantly changed at 24 hours after onset in any of the patients with the first pattern, but resolved completely in all patients with the latter two patterns. Follow-up imaging showed large infarctions in all patients with the first pattern. Initially, no infarction was seen in the second pattern, but watershed infarction developed later in one of these patients.. Hyperacute ischemic stroke may be differentiated into three imaging patterns with different clinical outcomes. The combined use of perfusion-weighted MR imaging and MR angiography may play a substantial role in guiding the choice of treatment of this disease.

Topics: Acute Disease; Aged; Aged, 80 and over; Arterial Occlusive Diseases; Blood Volume; Brain Ischemia; Cerebral Arterial Diseases; Cerebral Infarction; Cerebrovascular Circulation; Cerebrovascular Disorders; Contrast Media; Female; Follow-Up Studies; Humans; Image Enhancement; Magnetic Resonance Angiography; Magnetic Resonance Imaging; Male; Middle Aged; Patient Care Planning; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

SPECT using 99mTc-hexamethyl propyleneamine oxime (HMPAO) mainly reflects regional cerebral blood flow, however metabolic abnormalities also affect the retention of 99mTc-HMPAO.. To rule out any flow factor, a test-tube model was used to evaluate the effects of metabolic alterations both on intracellular trapping of 99mTc-HMPAO and on extracellular glutamate and lactate dehydrogenase (LDH) outflow from rat brain slices.. Under control conditions, slices took up 7.0%+/-1.4% of 99mTc-HMPAO contained in the medium, whereas prelabeled slices released 10.8%+/-2.6% of their radioactive content; glutamate and LDH outflow were 49.1+/-21.6 pmol/mg protein/ min and 4.8+/-0.9 U/L/mg protein/min, respectively. The control medium was altered by adding a metabolic poison (5 mmol/L azide), removing glucose and replacing O2 with N2 to mimic ischemia (in vitro ischemia) and replacing Krebs solution with hypotonic medium to evoke cell lysis. Both azide and in vitro ischemia induced a significant increase in 99mTc-HMPAO release (15.8%+/-3.3% and 18.3%+/-6.2%, respectively), without any modification in LDH efflux. However, only azide reduced the uptake of the tracer. Conversely, glutamate outflow was massive during in vitro ischemia and was far lower during azide treatment. Under hypotonic medium conditions, the release of 99mTc-HMPAO, glutamate and LDH were dramatically increased. Surprisingly, a two-fold increase of 99mTc-HMPAO uptake was also found. When 1 mmol/L glutathione was added to the medium, to convert native lipophilic 99mTc-HMPAO into hydrophilic derivatives, tracer uptake was inhibited both under control and hypotonic medium conditions.. This study provides evidence that not only poisoning of the tissue but also in vitro ischemia induced a reduction of 99mTc-HMPAO retention. Moreover, we demonstrated that injuries causing cell membrane disruption led to hyperfixation of 99mTc-HMPAO.

Topics: Animals; Azides; Brain; Brain Ischemia; Cerebrovascular Circulation; Glutamic Acid; In Vitro Techniques; L-Lactate Dehydrogenase; Male; Radiopharmaceuticals; Rats; Rats, Sprague-Dawley; Technetium Tc 99m Exametazime

Previous studies have shown the usefulness of divalent cobalt isotopes to visualize cerebral damage after stroke. The site of accumulation of cobalt ion is unknown but may be explained by neuronal influx, analogous to that of calcium ion. Additionally, uptake may be due to infiltrating leukocytes or protein-bound cobalt. The aims of this study were to compare 57Co-SPECT with leukocyte SPECT and to compare the SPECT findings with clinical outcome as scored by the Orgogozo scale.. Ten patients with a CT scan positive for middle cerebral artery infarcts were included in the study (7 men, 3 women; mean age 70 yr). Technetium-99m leukocyte and cobalt-SPECT (interval 2-4 days) were made with a double-headed gamma camera, after the injection of 10-15 mCi 99mTc-HMPAO-labeled leukocytes and 0.4 mCi 57Co, respectively. Scans were performed within 5-30 days after onset of the first symptoms. Regions of interest (ROI) containing the area of infarction in the slices displaying enhanced radioactivity or the middle cerebral artery (MCA) region in four successive slices were defined for calculating enhancement ratios. The 99mTc leukocyte enhancement ratio (LER) and cobalt enhancement ratio (CER) were defined as the quotient of radioactivity in the ROI and an identical contralateral ROI. The MCA stroke-scale according to Orgogozo was used to assess neurological deficits at the time of scanning and discharge.. Cobalt-57 and 99mTc-HMPAO showed uptake in the infarcted brain area in five patients; the quantitative uptake in the infarcted brain area of the two tracers correlated significantly (p < 0.05). Both the LER and the CER correlated significantly (p < 0.05) with the Orgogozo score at the time of scanning. Only the LER correlated significantly (p < 0.05) with the Orgogozo score at discharge.. Uptake of cobalt and leukocytes in the peri-infarct tissue suggests that 57Co may visualize a component of the inflammatory response. Divalent 57Co may be convenient to predict clinical prognosis after stroke.

Topics: Aged; Brain; Brain Ischemia; Cerebral Infarction; Cobalt Radioisotopes; Female; Humans; Leukocytes; Male; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Twenty-two patients with systemic lupus erythematosus and 13 healthy controls were included in a cerebral blood flow study and underwent brain-dedicated single-photon emission computed tomography using 99m technetium-d, l-hexamethylpropylene amine oxime together with a brain computed tomography scan. Plasma levels of antiphospholipid antibodies (lupus anticoagulant and anticardiolipin IgM and IgG antibodies) were also determined. Brain computed tomography showed signs of focal cerebral ischemia in 4 patients (18%), whereas cerebral blood flow by single-photon emission computed tomography was abnormal in 13 of 22 patients (59%), who showed bilateral or monolateral hypoperfusion in the temporo-parietal regions. Patients with abnormal cerebral blood flow had a longer duration of disease than those with normal blood flow (8.9 +/- 1.9 years vs. 5.3 +/- 1.5 years, P < 0.05). Plasma antiphospholipid antibodies were present in 15 patients (68%), but the prevalence was similar in those with normal (6/9, 66%), or abnormal (9/13, 69%) cerebral blood flow. No statistically significant difference in lupus anticoagulant or anticardiolipin antibodies was observed between patients with and without cerebral blood flow abnormalities. Our study shows that patients with systemic lupus erythematosus frequently have cerebral blood flow abnormalities, which could precede those observed by computed tomography. Plasma lupus anticoagulant and anticardiolipin titers were not correlated with normal cerebral blood flow.

Topics: Adolescent; Adult; Antibodies, Anticardiolipin; Autoimmune Diseases; Brain Ischemia; Cerebrovascular Circulation; Cerebrovascular Disorders; Child; Female; Humans; Lupus Coagulation Inhibitor; Lupus Erythematosus, Systemic; Male; Middle Aged; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Vasculitis

Extensive experience and critical evaluation of the efficacy of a pharmacologic hypotensive challenge during conventional balloon test occlusion (BTO) of the internal carotid artery (ICA) is lacking. This prompted us to review our institution's most recent experience with this adjunctive provocative test before planned therapeutic balloon occlusion of the ICA.. Twenty consecutive cases of endovascular therapeutic balloon occlusion of the ICA were retrospectively reviewed. Conventional BTO under normotension and with hypotensive challenge were performed within a standardized protocol.. Sixteen patients underwent provocative testing, of which 13 had BTO with hypotensive challenge. All patients in this group tolerated these maneuvers without acute neurologic deficit. Two (15%) of these patients developed delayed permanent neurologic deficits, which seemed to be attributable to hemodynamic ischemia. One of seven patients not undergoing hypotensive challenge also developed transient neurologic deficits after carotid occlusion.. Despite the conceptually attractive and early positive experience of the hypotensive challenge in attempting to increase sensitivity and specificity of risk for developing delayed hemodynamic ischemia, we have found two significant false-negative results. This experience is reviewed in the context of risks of permanent balloon occlusion of the carotid artery after balloon test occlusion.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Brain; Brain Ischemia; Carotid Artery Diseases; Carotid Artery, Internal; Catheterization; Cerebral Angiography; Child; Child, Preschool; Female; Humans; Intracranial Hypotension; Male; Middle Aged; Prognosis; Radiopharmaceuticals; Regional Blood Flow; Retrospective Studies; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

The rationale behind thrombolytic therapy in acute ischemic stroke is penumbral salvage by rapid restoration of cerebral blood flow. The relationship, however, between early reperfusion (potentially composed of both nutritional and nonnutritional components) and outcome remains unclear.. To establish the relationship between reperfusion parameters and outcome variables (Canadian Neurological Scale, Barthel Index, outcome CT scans), we used 99Tc-hexamethylpropyleneamine oxime (99Tc-HMPAO) single-photon emission CT (SPECT) to examine 41 acute ischemic stroke patients. All patients had at least 2 SPECT studies (24 with 3 studies), and none had been treated with thrombolytic or other acute investigational drugs.. A total of 106 studies were performed. Mean time to acute study was 9.2 hours; that for subacute study was 42 hours and for outcome study was 150 days. Hypoperfusion (HP) volumes at each of the 3 time points correlated with outcome clinical state and final infarct size. Both early reperfusion (61% of patients) and nutritional reperfusion alone (56%), which is early reperfusion maintained at outcome, were associated with improvement in clinical state and better functional outcome. Early HP volume change (acute minus subacute HP volume) and total HP volume change (acute minus outcome HP volume) also correlated with clinical improvement and better outcome.. This study establishes the benefit of spontaneous reperfusion after ischemic stroke and emphasizes the prognostic value of HP deficit volumes. 99Tc-HMPAO SPECT may be used to screen patients and group them according to perfusion deficit in acute stroke trials, thereby decreasing patient numbers required to show drug effect.

Topics: Adult; Aged; Aged, 80 and over; Brain Ischemia; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Humans; Male; Middle Aged; Nutritional Physiological Phenomena; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

The importance of MR imaging in carotid artery disease is unclear. We evaluated the sensitivity and specificity of the high signal intensity changes on MR images for diagnosis of hemodynamically compromised unilateral internal carotid artery disease.. We evaluated the association of high signal intensities on T2-weighted MR images with changes in cerebral perfusion reserve measured using 99mTc-hexamethylpropyleneamine oxime single-photon emission CT and acetazolamide in 23 patients.. Eleven patients had a type I response (normal flow and normal perfusion reserve), 8 patients had a type II response (normal flow and decreased perfusion reserve), and 4 patients had a type III response (decreased flow and decreased perfusion reserve). High signal intensities in the centrum semiovale (11/12) and/or posterior periventricular white matter (6/12) were frequently seen in the hemodynamically compromised groups. Extensive high signal intensities were associated with severely impaired cerebral circulation. MR imaging had high sensitivity (0.92) and specificity (1.0) in predicting hemodynamically compromised patients when we used the presence of T2 high intensity in the centrum semiovale as a criterion.. The centrum semiovale T2 hyperintensities lateralized to the side of carotid occlusion are specific and sensitive for the presence and severity of hemodynamic compromise from carotid occlusive disease.

Topics: Acetazolamide; Aged; Brain Ischemia; Carotid Stenosis; Cerebrovascular Circulation; Female; Humans; Intracranial Embolism and Thrombosis; Ischemic Attack, Transient; Magnetic Resonance Imaging; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Current routine clinical techniques, including angiography and perfusional single-photon emission tomography, can be used to indicate problems in cerebral vascular supply and areas of cerebral hypoperfusion following a stroke, but cannot distinguish between ischaemic core and penumbra. In order to image specifically the penumbra, a method or indicator should be able to define areas with reduced blood flow, and a degree of metabolic compromise. In this context, the tissue could be regarded as hypoxic rather than ischaemic, and we have therefore chosen to investigate the potential of radio-labelled hypoxic markers in the study of ischaemia. In order to combine a hypoxic marker with a blood flow marker we used technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) and iodine-125 iodoazomycin arabinoside (125I-IAZA), during cerebral ischaemia in the rat middle cerebral artery occlusion model. 99mTc-HMPAO and 125I-IAZA were injected simultaneously 2 h following occlusion of the middle cerebral artery, and 5 h before decapitation. Paired autoradiograms were produced and compared. Three distinct patterns emerged from the autoradiograms: slightly decreased perfusion with no uptake of the hypoxic marker indicating an area of misery perfusion; moderately decreased perfusion with concomitant uptake of iodoazomycin arabinoside, a region of hypoxia; and severely decreased perfusion with no retention of the hypoxic tracer. In conclusion, we present a new use for an imaging agent in the investigation of cerebral hypoxia. This agent, IAZA together with HMPAO, provides a means of separating the penumbra into regions of misery perfusion and hypoxia. The potential impact of this may be important in the clinical investigation of stroke.

Topics: Animals; Brain; Brain Ischemia; Cell Hypoxia; Cerebrovascular Circulation; Iodine Radioisotopes; Male; Nitroimidazoles; Organotechnetium Compounds; Oximes; Radionuclide Imaging; Rats; Rats, Wistar; Technetium Tc 99m Exametazime

Single-photon emission tomography (SPET) is widely used in the investigation of acute stroke. We investigated the relationship between SPET data and functional outcome in a large group of acute stroke patients. One hundred and eight patients underwent cerebral computed tomography (CT) and technetium-99m hexamethylpropylene amine oxime SPET after acute ischaemic stroke. We categorised the clinical presentation according to the Oxford classification of acute stroke. Outcome was measured 1 year after stroke using mortality and the Barthel Index for survivors. SPET scans were interpreted without reference to the clinical data using a semi-automatic technique. Three experienced observers determined the presence of luxury perfusion using suitably scaled SPET images in conjunction with the CT scan. Both SPET volume and severity of deficit were significantly negatively correlated with Barthel Index at 1 year (rs=-0.310, P<0.0001, and rs=-0.316, P<0.0001 respectively). In patients scanned with SPET within 16 h of stroke onset, the correlations were more strongly negative (rs=-0.606, P<0. 001, and rs=-0.492, P<0.005 respectively). Luxury perfusion was not associated (chi2=0.073, df=1, P=0.79) with good functional outcome (Barthel score >/=60). Stepwise logistic regression identified Oxford classification, total deficit volume and patient's age as significant predictors of functional outcome. Overall predictive accuracy was 72%. Predictive accuracy was better in patients who received SPET within 16 h of stroke onset. SPET provides useful information about the functional outcome of acute stroke at 1 year. However, the accuracy of prediction decreases the longer SPET is delayed. Prognostication using SPET in combination with clinical assessment and other investigations may also be considered.

Topics: Aged; Brain; Brain Ischemia; Cerebrovascular Circulation; Follow-Up Studies; Humans; Logistic Models; Organotechnetium Compounds; Oximes; Predictive Value of Tests; Prognosis; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

The aim of our work was to study the state of regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) in patients with different degree of carotid stenosis after CE. Thirty six patients with carotid stenosis aged 46-65 years (mean age 55 years) were studied. In all the patients before and one month after carotid endarterectomy (CE) single photon emission computed tomography (SPECT) with 99mTc-hexamethylpropylene amine oxime (99mTc-HMPAO, Ceretec, Amersham) and SPECT with labelled in vivo 99mTc-red blood cells (99mTc-RBC) were carried out. According to the results of scintigraphic studies the regional cerebral blood flow (rCBF, ml/min/100g), the volume of hypoperfusion (Vhypoperf., sm3), the stroke volume (SV, sm3), the interhemispheric ratio of rCBF (IRrCBF) and the regional cerebral blood volume (rCBV, ml/100g) were calculated. CE leads to the bilateral increase of cerebral perfusion especially at the side of more expressed damage putting away interhemisphere asymmetry of rCBF. After CE the regression of SV and Vhypoperf were revealed. In asymptomatic disease patients with monolateral stenosis of carotid arteries rCBF reaches normal values and regions of hypoperfusion are not revealed. Surgical recanalization of carotid arteries causes expressed changes of scintigraphic parameters of rCBV: normalization of initially increased values of rCBV in patients with asymptomatic development of stenosed atherosclerosis of carotid arteries and subsequent increase of rCBV in comparison with preoperative level in patients who underwent acute stroke with neurological deficit and patients with poor clinical signs and multiple damage of both internal carotid arteries.

Topics: Acute Disease; Aged; Arteriosclerosis; Blood Volume; Brain; Brain Ischemia; Carotid Artery, Internal; Carotid Stenosis; Cerebrovascular Circulation; Cerebrovascular Disorders; Endarterectomy, Carotid; Erythrocytes; Female; Follow-Up Studies; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Radiopharmaceuticals; Stroke Volume; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Some of the clinical features of obstructive sleep apnoea syndrome (OSA) are suggestive of impaired cerebral blood flow. Cerebral blood flow alterations might, for example, be responsible for headaches, which are frequent complaints in patients with OSA. Even the high frequency of ischaemic cerebral complications in patients with OSA might be caused in part by sleep apnoea-associated impairment of cerebral perfusion. Previous studies have demonstrated reduced total cerebral blood flow in patients with OSA, but regional changes of cerebral perfusion have not been studied up to now. We performed SPECT studies using 99mTc-(d,l)-hexamethyl-propylenaminoxim (HMPAO) as a tracer in 14 adult patients with moderate to severe OSA (AHI > 30/h; mean AHI 59.2 +/- 4.3). The injection of the tracer took place between 2:00 and 4:00 a.m. while repeated episodes of obstructive apnoea were detected by polysomnography during stage II sleep. Data acquisition took place at 7:30 a.m. All measurements were repeated some nights later under effective treatment with nCPAP. Visual analysis showed marked frontal hyperperfusion in 5 patients. When regional perfusion indices were calculated for 32 regions of interest statistical analysis showed reduced perfusion of the left parietal region. These changes were completely reversed by effective nCPAP therapy. These data suggest that OSA is associated with reversible changes of regional cerebral perfusion. The underlying pathophysiologic mechanisms are matter of speculation so far. There might be an apnoea-associated effect of local vascular autoregulation mechanisms acting to compensate systemic blood flow alterations or blood gas changes in OSA. The observed frontal hyperperfusion might be caused by activation of the frontal lobe by repetitive cortical arousals.

Topics: Adult; Aged; Brain; Brain Ischemia; Circadian Rhythm; Female; Humans; Injections, Intravenous; Male; Middle Aged; Regional Blood Flow; Sleep Apnea Syndromes; Sleep Stages; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Psychiatric, neuropsychological, and cerebral blood flow differences between patients with ischemic vascular dementia (IVD) or Alzheimer's disease (AD) were examined.. A consecutive series of patients who met either the criteria of the National Institute of Neurological Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association for probable AD or the State of California AD Diagnostic and Treatment Centers criteria for probable IVD were included in the study. Twenty consecutive patients with IVD were matched for age, sex, and Mini-Mental State Examination scores with 40 consecutive patients with probable AD. Patients underwent a psychiatric interview, a neuropsychological assessment, and single-photon emission CT imaging with 99mTc-hexamethylpropyleneamine oxime.. Patients with IVD showed significantly more severe anosognosia (P<.05) and emotional lability (P<.01) than AD patients, but no significant between-group differences were found in the frequency and severity of depression. IVD patients showed significantly more severe deficits in tests of planning, sequencing (P<.05), and verbal fluency (P<.05) as well as significantly more severe cerebral blood flow deficits in the basal ganglia (P<.01) and the frontal lobes (P<.001) than AD patients.. Patients with IVD showed a relatively more severe dysfunction of the frontal lobes as demonstrated by single-photon emission CT and expressed in specific psychiatric and neuropsychological changes than AD patients matched for age, sex, and severity of dementia.

Topics: Aged; Alzheimer Disease; Basal Ganglia; Brain Ischemia; Case-Control Studies; Cerebrovascular Circulation; Cognition Disorders; Dementia, Vascular; Depression; Emotions; Female; Frontal Lobe; Humans; Interview, Psychological; Male; Mental Health; Neuropsychological Tests; Neuropsychology; Organotechnetium Compounds; Oximes; Self Concept; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Verbal Behavior

Single-photon emission computed tomography (SPECT) with 99mtechnetium-hexamethylpropylamineoxime (HMPAO) noninvasively shows brain perfusion in patients after acute stroke. However, the clinical significance of the increased HMPAO uptake remains unclear. In this study, consecutive patients with hemispheric hemorrhagic and ischemic stroke admitted to the hospital were evaluated prospectively. The increased uptake of HMPAO was determined by visual analysis of SPECT images. The pathogenic mechanism of ischemic stroke was determined using the clinical and computed tomography (CT) criteria including the Toronto Embolic Scale. Of the 500 consecutive patients with acute hemispheric stroke, SPECT was performed in 458 at a mean time 5 +/- 7 days after the onset of symptoms. A strong association was found between SPECT perfusion patterns and pathogenic subtypes of stroke (p < 0.0001). Thus, in 95% of patients with intracerebral hemorrhage the focal absence of perfusion was found, and 26% of lacunar infarctions presented with a normal SPECT appearance. The mean volume of lacunar lesions that did not produce significant abnormalities on SPECT was 2.5 +/- 1.2 ml. Increased HMPAO uptake was associated with a cardioembolic mechanism of stroke: High and mixed perfusion patterns were present subacutely in 29% of patients with cardioembolic stroke, compared to 15% of patients with other types of ischemic stroke (p < or = 0.0006). The increased uptake of HMPAO on SPECT as determined by visual analysis is associated with a cardioembolic mechanism of cerebral ischemia, which could be explained by glutathione-mediated trapping of the tracer during reperfusion and later in newly developed granulation tissue. HMPAO-SPECT may help in early management decisions since it indicates stroke pathogenesis and evolution.

Topics: Acute Disease; Aged; Brain; Brain Ischemia; Cerebral Hemorrhage; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Glutathione; Granulation Tissue; Humans; Intracranial Embolism and Thrombosis; Male; Middle Aged; Organotechnetium Compounds; Oximes; Prospective Studies; Reperfusion; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

A 60-yr-old woman experienced several episodes of generalized seizures following 2 wk of immunosuppressive therapy with cyclosporine for orthotopic liver transplantation. CT showed low density in the white matter of the parieto-occipital lobes. A 99mTc-HMPAO brain SPECT showed diminished perfusion in the parieto-occipital cortex bilaterally. Although the cyclosporine was discontinued, the patient's neurologic status initially worsened and then improved over the next several days. Repeat perfusion brain SPECT showed resolution of most of the perfusion abnormalities, while repeat CT showed persistent white matter changes in the parieto-occipital lobes. We report the presence of reversible cortical perfusion abnormalities in conjunction with cyclosporine therapy. The findings suggest that perfusion brain SPECT may be a sensitive monitor of cyclosporine-induced neurotoxicity.

Topics: Brain; Brain Ischemia; Cerebrovascular Circulation; Cyclosporine; Female; Humans; Immunosuppression Therapy; Liver Transplantation; Middle Aged; Occipital Lobe; Organotechnetium Compounds; Oximes; Parietal Lobe; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Brain 99Tcm-HMPAO single photon emission tomography (SPET) and 1H-MRS (proton magnetic resonance spectroscopy) were used to determine correlations between alterations in regional cerebral blood flow (rCBF) and changes in neuronal metabolites in 21 patients (28 examinations) with ischaemic cerebral infarction examined in different phases. rCBF was determined semi-quantitatively using Lassen's linearization algorithm. SPET provided evidence of the hypoperfused site of necrosis within a few hours after the acute event and alterations in rCBF were detected in both the infarcted and diaschistic areas at all stages. 1H-MRS was used to monitor the concentration of the following metabolites: N-acetyl-aspartate (NAA), creatine and phosphocreatine (CR + PCr), compounds containing choline (Cho) and lactate (Lac). A significant correlation was found between reduction in rCBF and a fall in NAA and Cr + PCr in both the acute and chronic phases, but not during "luxury perfusion' in the subacute phase. The presence of LAC in the infarcted area up to 9 months post-ictus was totally unexpected. Simultaneous SPET and 1H-MRS thus provides additional information regarding the physiopathogenesis of cerebral ictus by clarifying the relation between alterations in rCBF and biochemical neuronal changes. We believe that NAA and Cr + PCr concentrations are the best expression of agreement between flow and metabolism in infarcted areas, particularly with regard to hypoperfused areas not clearly detectable by magnetic resonance imaging in the early post-ictus stage.

Topics: Adult; Aged; Aspartic Acid; Brain Ischemia; Cerebral Infarction; Cerebrovascular Circulation; Choline; Creatine; Female; Humans; Lactates; Lactic Acid; Magnetic Resonance Imaging; Male; Middle Aged; Organotechnetium Compounds; Oximes; Phosphocreatine; Protons; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Does the absolute value of the stump pressure (post-occlusion back pressure) become a useful index of a good collateral circulation? The authors continuously monitored the mean arterial pressure before, during and after 20-minute balloon test occlusion in 24 patients. The stump pressure was then compared with the results of 99mTc-hexa-methyl propyleneamine (99mTc-HMPAO) single photon emission computed tomography (SPECT) performed after 20 minutes of test occlusion. Patients who failed to tolerate even brief periods of carotid occlusion and showed asymmetric decreases in cerebral blood flow (CBF) on SPECT were divided into high and moderate risk groups. Those with no significant change in CBF on the occluded side formed the minimum risk group. Mean stump pressure was over 50 mmHg in three of a total of 13 patients in the high and moderate risk groups, and below 50 mmHg in two of the 11 patients in the minimum risk group. The ratios of the initial mean stump pressure to the pre-occlusion mean arterial pressure (%) and of the final mean stump pressure at the end of occlusion to the post-opening mean arterial pressure (%) did not exceed 58% in any patient in the high and moderate risk groups, and were at least 60% in all patients of the minimum risk group. Maintenance of a mean stump pressure of 60% or more of the mean systemic pressure during test occlusion may be a more useful index of a good collateral circulation than the absolute value of mean stump pressure.

Topics: Adult; Aged; Blood Pressure; Brain; Brain Ischemia; Carotid Artery Diseases; Carotid Artery, Internal; Catheterization; Cerebral Revascularization; Collateral Circulation; Dominance, Cerebral; Female; Humans; Intracranial Aneurysm; Male; Meningeal Neoplasms; Meningioma; Middle Aged; Monitoring, Physiologic; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

To clarify the clinical significance of fibrinolytic therapy for acute ischemic stroke.. We analyzed findings in 18 patients with occlusion of a major artery in respect to cerebral blood flow thresholds for infarction. Nine of these patients had shown complete recanalization just after the treatment, between 3.5 and 7.25 hours after symptom onset, and the other nine had shown no change. Cerebral blood flow was measured by single-photon emission CT using 99mTC-labeled hemamethylpropyleneamine oxime and assessed semiquantitatively: multiple regions of interest were placed on the section images and two parameters, the R/CL ratio and the R/CE ratio, were calculated (where R represents a mean count of the region of interest in the affected hemisphere, CL on the opposite side, and CE in the cerebellar hemisphere on the affected ischemic side).. Reperfusion significantly reduced the development of infarction in the regions of interest with an R/CL ratio between 0.65 and 0.85 or an R/CE ratio between 0.55 and 0.75. No correlation was observed between the development of infarction and the duration of ischemia. The cerebral blood flow threshold in patients without recanalization was higher than that in patients with recanalization.. Reperfusion achieved by fibrinolytic therapy in the acute stage can save ischemic brain within a limited cerebral blood flow value.

Topics: Aged; Brain; Brain Ischemia; Cerebral Infarction; Dominance, Cerebral; Dose-Response Relationship, Drug; Female; Follow-Up Studies; Humans; Intracranial Embolism and Thrombosis; Male; Middle Aged; Organotechnetium Compounds; Oximes; Regional Blood Flow; Technetium Tc 99m Exametazime; Thrombolytic Therapy; Tissue Plasminogen Activator; Tomography, Emission-Computed, Single-Photon; Urokinase-Type Plasminogen Activator

Retrograde cerebral perfusion (RCP) via the superior vena cava has been described as an adjunctive technique to enhance the safety of hypothermic circulatory arrest (HCA), but perfusion of cerebral tissue in humans during RCP has not been demonstrated to date. We report our clinical experience with RCP and our attempt to demonstrate "true" perfusion of the brain.. Between April 1993 and June 1995, 49 thoracic aortic procedures were performed in 48 patients (male:female = 26:22) (emergency: elective = 25:24). The indications for surgery were acute type "A" dissection (18) chronic aneurysm (28) and infected valved conduit (3). Hypothermic circulatory arrest (15 degrees C) and RCP were implemented in all cases (mean HCA time 29 min, range 11-69) (mean RCP time 26 min, range 10-65). The 99mTechnetium labelled brain perfusion agent d,l, hexamethyl propylene amine oxime (99mTc-HMPAO) was administered (100 MBq) into the cardiotomy reservoir following institution of HCA (15 degrees C) in three consecutive patients and planar dynamic brain imaging with a portable gamma camera was commenced at the start of RCP.. Six hospital deaths (12.2%) occurred in the emergency group due to atheromatous embolic stroke in one patient, sepsis in one, ruptured infrarenal aortic aneurysm in one, myocardial failure in one, renal failure in one and multi-system organ failure in one patient. The remaining patients suffered no major neurological complications (median Intensive Care Unit stay 1 day, range 1-5). Inspection of the images acquired showed 99mTc-HMPAO activity spreading quickly from the jugular bulb and the superior sagittal sinus throughout the cerebral white and gray matter. Time-activity curves calculated for both cerebral hemispheres showed homogeneous regional cerebral perfusion.. Retrograde cerebral perfusion is easy to establish, "safe" and provides blood flow to the brain during HCA. The flow quantification and metabolic contribution of RCP require further investigation.

Topics: Adult; Aged; Aged, 80 and over; Aortic Aneurysm, Thoracic; Aortic Dissection; Blood Vessel Prosthesis; Brain; Brain Ischemia; Cause of Death; Female; Gamma Cameras; Heart Arrest, Induced; Hospital Mortality; Humans; Intraoperative Complications; Male; Middle Aged; Organotechnetium Compounds; Oximes; Perfusion; Prosthesis-Related Infections; Radionuclide Imaging; Regional Blood Flow; Survival Rate; Technetium Tc 99m Exametazime; Vena Cava, Superior

Topics: Acute Disease; Brain; Brain Ischemia; Fibrinolytic Agents; Humans; Organotechnetium Compounds; Oximes; Randomized Controlled Trials as Topic; Technetium Tc 99m Exametazime; Thrombolytic Therapy; Tomography, Emission-Computed, Single-Photon

Premature fusion of multiple cranial sutures has been associated with increased intracranial pressure and the potential for mental impairment. Isolated craniosynostosis, however, has been thought to be a benign condition primarily reconstructed for aesthetic purposes. On the basis of subjective developmental improvement postoperatively, an objective radiographic analysis (single positron emission computed tomography [SPECT] was used to assess differences in cerebral perfusion in the areas compressed secondary to the fused cranial suture both before and after cranial reconstructive surgery in patients with simple craniosynostosis. Seven children with craniosynostosis, six boys and one girl (age age, 3-28 months), were enrolled in this prospective study. Six of the seven had cranial asymmetry on preoperative cranial computed tomographic scans, and one had a symmetric defect and was used as a control. Each subject had a preoperative SPECT scan approximately 3 to 5 days before the cranial reconstruction procedure and a follow-up scan 6 to 10 weeks postoperatively. Preoperative asymmetries in cerebral perfusion ranged from 0 to 30% (mean, 13%) the areas compressed secondary to the premature suture fusion. In five patients cerebral blood flow, which was asymmetric before surgery, became symmetric after craniofacial reconstruction, and no new perfusion defects were documented. The control patient and one another patient had symmetric perfusion both pre- and postoperatively. Craniosynostosis may be associated with decreased cerebral blood flow as a result of the constriction of the brain from the prematurely fused suture. The correction of asymmetric cranial single-suture synostosis is more than a cosmetic procedure in that it allows for normalization of cerebral blood flow. This difference in blood flow supports early surgical intervention to prevent any potential central nervous system compromise secondary to abnormal blood flow.

Topics: Brain; Brain Ischemia; Cerebral Angiography; Cerebrovascular Circulation; Child, Preschool; Craniosynostoses; Female; Humans; Infant; Male; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Two-dimensional regional cerebral blood flow (rCBF) was measured using the xenon-133 inhalation method, and used to calibrate the rCBF measured by single photon emission computed tomography (SPECT) in the non-affected middle cerebral artery (MCA) area. The value of the rCBF in the target area could then be measured by SPECT and compared between patients. Technetium-99m-d,l-hexamethyl-propylene-amine-oxime and technetium-99m-diethylenetriaminepenta-acetic acid-human serum albumin D were used to measure rCBF and regional cerebral blood volume (rCBV), respectively, in the ischemic area of 16 patients who underwent surgical revascularization in the chronic stage. No significant increase in rCBF was obtained after the bypass surgery. The delta rCBF and delta CBF/CBV ratio correlated well with the extent of vascularization in the MCA area on postoperative angiograms. Patients with a low CBF/CBV ratio on preoperative SPECT scans tended to show favorable postoperative vascularization and rCBF in the MCA area. Since the angiographic findings and the delta rCBF or delta CBF/CBV were correlated well, this simple and non-invasive method could be used for the analysis of rCBF in a group of patients.

Topics: Aged; Blood-Brain Barrier; Brain; Brain Ischemia; Female; Humans; Male; Middle Aged; Radiopharmaceuticals; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Xenon Radioisotopes

To investigate the utility of neuroreceptor imaging in ischaemic cerebrovascular disorders, dual-tracer autoradiography using 99Tcm-hexamethylpropyleneamine oxime (HMPAO) for the evaluation of cerebral blood flow and 125I-iomazenil for the evaluation of central-type benzodiazepine receptor density was performed in experimental brain ischaemia created by occlusion of the unilateral middle cerebral artery of the rat. In the acute phase of ischaemia, 125I-iomazenil accumulation showed less of a decrease than 99Tcm-HMPAO in the cerebral cortex of the lateral convexity and in the lateral segment of the caudate putamen in the lesioned cerebral hemisphere. In the sub-acute phase, both 125I-iomazenil and 99Tcm-HMPAO accumulation increased in the lesion compared with the acute phase. A large accumulation of 99Tcm-HMPAO and 125I-iomazenil in the lesion was considered to be due to luxury perfusion and penetration of 125I-iomazenil hydrophilic metabolites from the blood into the brain tissue through the altered blood-brain barrier. In the chronic phase, 125I-iomazenil accumulation showed a more marked decrease than 99Tcm-HMPAO in the lesion. Moreover, the ipsilateral thalamus, which is remote from the lesion, revealed decreased 125I-iomazenil accumulation despite normal 99Tcm-HMPAO accumulation. Since the central-type benzodiazepine receptors are principally located not on the glial cells but on the neurons, the receptor density may exhibit a change that parallels the neuron density. These results suggest that central-type benzodiazepine receptor imaging is useful for the evaluation of neuronal damage when used in conjunction with brain perfusion imaging in ischaemic cerebrovascular disorders, except in the sub-acute phase.

Topics: Acute Disease; Animals; Autoradiography; Brain; Brain Ischemia; Chronic Disease; Flumazenil; Functional Laterality; Iodine Radioisotopes; Male; Organ Specificity; Organotechnetium Compounds; Oximes; Radionuclide Imaging; Rats; Rats, Inbred Strains; Receptors, GABA-A; Technetium Tc 99m Exametazime

The "spectacular shrinking deficit" (SSD) refers to a syndrome of profound hemispheric ischemia that resolves rapidly over hours to days, leaving patients with minimal residual neurologic deficits. The SSD is postulated to result from rapid embolic lysis, fragmentation, and migration along the internal carotid/middle cerebral artery axis, leading to restored tissue perfusion before irreversible tissue damage has occurred. We performed serial single-photon emission computed tomographic (SPECT) cerebral perfusion measurements during the first 48 hours in 36 patients admitted with major hemispheric ischemia, to compare the cerebral perfusion changes between patients who developed SSD (n = 5) and those who did not (n = 31). The two groups were similar for severity of neurologic deficit, time of SPECT study, and size of perfusion defect on the SPECT images. Patients with SSD were younger (p = 0.02, Mann-Whitney U), demonstrated significantly greater tissue reperfusion during the first 48 hours (p < 0.01), and had smaller infarcts on CT (p = 0.02). This syndrome provides an opportunity to understand the mechanism by which early reperfusion may result in early tissue salvage and clinical recovery.

Topics: Aged; Brain Ischemia; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Single-photon emission computed tomography (SPECT) and transcranial Doppler sonography (TCD) may help to determine a target group of patients with maximum therapeutic response for tissue rescue after acute stroke. As previously described, the cerebral perfusion index represents a combination of these techniques, and is calculated by multiplying assigned values for TCD and SPECT perfusion patterns. The three grades of cerebral perfusion index (1-5, 6-12, 15-20) may predict short-term outcome if the index is based on SPECT and TCD performed within the first 6 hours after stroke. A total of 30 consecutive patients were studied (18 with middle cerebral artery stroke and 12 with transient ischemic attack or minor stroke). Neurological deficit was scored using the Canadian Neurological Scale. SPECT and TCD were performed 4 +/- 2 hours after the onset. Forty-five minutes were required to perform both tests, evaluate the results, and calculate the cerebral perfusion index. The mean score (+/- standard deviation) of the neurological deficit on admission was 84 +/- 20 in patients with transient ischemic attack/minor stroke and 54 +/- 33 in patients with stroke (p < 0.009). The volume of ischemic lesion was measured on computed tomography scans performed more than 3 days after the ictus. Patients with transient ischemic attack/minor stroke had lesion volumes of 8 +/- 7 cm3 compared to 72 +/- 26 cm3 for those with stroke (p < 0.0001). The mean cerebral perfusion index in the transient ischemic attack group was 18 +/- 4, while in the stroke group it was 4 +/- 1 (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acute Disease; Aged; Brain Ischemia; Cerebral Infarction; Cerebrovascular Circulation; Cerebrovascular Disorders; Echoencephalography; Female; Humans; Ischemic Attack, Transient; Male; Neurologic Examination; Organotechnetium Compounds; Oximes; Prospective Studies; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Ultrasonography, Doppler, Transcranial

In this study we aimed to work out a quantitative prognostic index for preoperative assessment of brain technetium-99m hexamethylpropylene amine oxime (HMPAO) single-photon emission tomography (SPET) in patients referred for urgent carotid endarterectomy due to acute obstructive disease of the internal carotid artery (ICA) and neurological deficit. To this end we compared data from preoperative SPET studies with the postinterventional changes in neurological status in 20 patients (17 males, three females; mean age 53 years, SD 4 years) with acute ischaemic cerebral disorders induced by obstruction of the ICA. Carotid obstruction was diagnosed by ultrasound B-mode study. All patients underwent urgent carotid endarterectomy from the ICA. Patients were divided into two groups in accordance with the results of postoperative follow-up: group A comprised patients with significant (more than 3 points) postoperative improvement in neurological condition as quantified by the Canadian Neurological Scale (11 patients); group B consisted of patients with minimal improvement or deterioration (nine, three of whom died). All patients were studied preoperatively by 99mTc-HMPAO SPET. The volume of nonperfused tissue (VS, cm3) was quantified using the Mountz technique. Hypoperfused volume (Vhypoperf, cm3) in the affected hemisphere was calculated as the total volume of voxels with 99mTc-HMPAO uptake < 90% of the contralateral symmetric voxels. Discriminant prognostic function was calculated by discriminant analysis as: PF = 0.072 x VS + 29.46x(VS/Vhypoperf). Patients with preoperative PF values < 8.20 demonstrated postoperative improvement in neurological status, while the group with PF > 8.90 comprised patients who demonstrated minimal improvement or deterioration. PF values in the range 8.20-8.90 carried an indefinite prognosis. We conclude that the preoperative 99mTc-HMPAO SPET can be used for the selection of patients in whom improvement in neurological status may be expected after urgent surgical correction of acute extracranial obstruction of the ICA.

Topics: Brain; Brain Ischemia; Carotid Artery, Internal; Carotid Stenosis; Emergencies; Endarterectomy, Carotid; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Prognosis; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Ultrasonography

A 75-year-old man who had a small right parietal infarction 8 months earlier underwent baseline and acetazolamide enhanced Tc-99m hexamethylpropylene amineoxime brain SPECT imaging. The acetazolamide study demonstrated a bilaterally symmetric perfusion deficit posteriorly near the midline. The baseline study was essentially normal. This finding was felt to represent watershed ischemia at the junction of the anterior circulations (anterior cerebral and middle cerebral arteries) and the posterior circulation (posterior cerebral artery). Carotid arteriography subsequently demonstrated left subclavian steal syndrome with retrograde flow through the left vertebral artery.

Topics: Acetazolamide; Aged; Brain; Brain Ischemia; Cerebral Angiography; Humans; Image Processing, Computer-Assisted; Male; Organotechnetium Compounds; Oximes; Subclavian Steal Syndrome; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cerebral vasospasm (CVS) occurs as a result of the breakdown in cerebral autoregulation mechanisms. Because cerebral vasospasm can occur after subarachnoid hemorrhage (SAH), it is important to evaluate borderline perfusion. Evaluation of borderline vascular insufficiency is important to reduce ischemic complications. In this study 25 patients with SAH were investigated by somatosensory evoked potentials (SEP), computed tomography (CT), digital subtraction angiography (DSA) and single photon emission computed tomography (SPECT) in order to predict borderline ischemic areas. Clinical grades were also correlated with these investigations. Thirteen patients had symptomatic vasospasm and 15 patients had angiographic vasospasm. SPECT showed hypoperfusion in 22 out of 25 patients. CT predicted CVS in 8 of these 22 patients. Our study shows that brain perfusion SPECT is a non-traumatic, non-invasive, non-allergic, inexpensive method for the prediction of cerebral vasospasm. We conclude that brain SPECT with Tc-99m HM-PAO is an accessible technique that can demonstrate varying degrees of regional tissue hypoperfusion in patients with delayed ischemic deficits due to CVS following SAH.

Topics: Adolescent; Adult; Brain Ischemia; Child; Female; Homeostasis; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Regional Blood Flow; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The aim of the study was to depict regional cerebral blood flow (rCBF) during carotid cross clamping using 99mTechnetium-hexamethylpropylene amine oxime (TcHMPAO). This tracer rapidly passes the blood-brain barrier and is retained for hours in the brain tissue. Injecting TcHMPAO during surgery and performing single photon emission computer tomography (SPECT) scanning shortly after the operation thereby pictures rCBF at the time of injection.. Ongoing prospective study.. Departments of Vascular Surgery, Neurology and Anaesthesiology, University Hospital, Rigshospitalet, Copenhagen, Denmark.. 15 patients who during a period of 4 months underwent carotid endarterectomy.. Prior to surgery rCBF was determined using 133Xe and SPECT. Intraoperatively stump pressure was measured and a bolus of TcHMPAO was injected for later SPECT measurement.. We found a significant correlation between stump pressure and enhancement of side-to-side asymmetry in rCBF due to carotid cross clamping. Pronounced variations were seen in which regions were deprived of perfusion during clamping.. TcHMPAO allows tomographic assessment of CBF during carotid surgery. This method may serve as a reference tool in future research on intraoperative cerebral haemodynamics.

Topics: Aged; Brain; Brain Ischemia; Carotid Stenosis; Endarterectomy, Carotid; Female; Hemodynamics; Humans; Intraoperative Complications; Male; Middle Aged; Organotechnetium Compounds; Oximes; Prospective Studies; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

A protocol has been devised to effectively extend the limited post-reconstitution shelf life of technetium-99m exametazime as a radiopharmaceutical for imaging cerebral blood flow (CBF) distribution. The potential of 99mTc-exametazime stabilised with cobalt chloride for imaging CBF distribution as late as 4 h after reconstitution has been examined in ischaemic and non-ischaemic tissue in halothane-anaesthetised cats. Focal cerebral ischaemia was produced by permanent middle cerebral artery occlusion. The relationship between 99mTc-exametazime uptake and retention and CBF (assessed with [14C]iodoantipyrine 10 min after first radiopharmaceutical administration) was determined in the same tissue section with double label autoradiography. Over the CBF range 0-80 ml 100 g-1 min-1, the uptake of 99mTc-exametazime (quantitatively and topographically) was linearly related to CBF irrespective of whether the 99mTc-labelled tracer was unstabilised (and administered within 10 min of reconstitution) or was stabilised with cobalt chloride (and administered up to 240 min after reconstitution). For levels of CBF in excess of 80 ml 100 g-1 min-1 the excellent topographical relationship between 99mTc-exametazime distribution and CBF is maintained but quantitatively, 99mTc-exametazime underestimates CBF to a similar degree in animals receiving stabilised and unstabilised 99mTc-exametazime. The presence of the stabiliser, cobalt chloride, extends greatly the period over which 99mTc-exametazime can be used after reconstitution to generate images of CBF distribution in normal and ischaemic cerebral tissue.

Topics: Animals; Brain; Brain Ischemia; Cats; Cerebrovascular Circulation; Cobalt; Drug Stability; Organotechnetium Compounds; Oximes; Reagent Kits, Diagnostic; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

The popular concept that cerebral ischemia causes transient global amnesia has been difficult to prove by cerebral blood flow studies during attacks because the transient global amnesia attacks are so short.. We performed single-photon emission computed tomography (SPECT) of the brain and neuropsychological assessment in a 37-year-old woman during a 10-hour attack and twice thereafter. A neuropsychological evaluation 3 hours after the onset of transient global amnesia revealed severe impairment of recent memory and verbal fluency, both of which returned to normal 2 and 28 days later, respectively. A 99mTc-labeled hexamethylpropyleneamine oxime SPECT of the brain performed 6 hours after the onset showed multiple perfusion defects in both occipital lobes, the medial left temporal lobe, and the left thalamus. A second brain SPECT performed 3 days later showed perfusion defects in only the occipital regions. A third brain SPECT performed 28 days later was normal. The patient's brain computed tomographic scan, electroencephalogram, duplex ultrasound of the carotid artery, and echocardiogram were normal.. The perfusion defects revealed by the brain SPECT during the transient global amnesia attack indicated ischemia in the territory of the posterior cerebral arteries, which partially resolved in 3 days and completely resolved by 28 days.

Topics: Adult; Amnesia; Brain Ischemia; Female; Hemiplegia; Humans; Neurologic Examination; Occipital Lobe; Organotechnetium Compounds; Oximes; Regional Blood Flow; Technetium Tc 99m Exametazime; Temporal Lobe; Thalamus; Tomography, Emission-Computed, Single-Photon

Topics: Brain; Brain Ischemia; Cerebrovascular Disorders; Humans; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime

Single-photon emission computed tomography (SPECT) with 99mTc-hexamethylpropyleneamine oxime (HMPAO) was used to investigate changes in cerebral blood flow in seven patients with cortical visual impairment. Traumatic brain injury (TBI) was the cause of cortical damage in two patients, cerebral ischemia in two patients and carbon monoxide (CO) poisoning, status epilepticus and Alzheimer's Disease (AD) each in three separate patients. The SPECT scans of the seven patients were compared to T2-weighted magnetic resonance image (MRI) scans of the brain to determine the correlation between functional and anatomical findings. In six of the seven patients, the qualitative interpretation of the SPECT studies supported the clinical findings (i.e., the visual field defect) by revealing altered regional cerebral blood flow (rCBF) in the appropriate regions of the visual pathway. MR scans in all of the patients, on the other hand, were either normal or disclosed smaller lesions than those detected by SPECT. We conclude that SPECT may reveal altered rCBF in patients with cortical visual impairment of various etiologies, even when MRI studies are normal or nondiagnostic.

Topics: Adult; Aged; Brain Injuries; Brain Ischemia; Cerebrovascular Circulation; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Vision Disorders; Visual Cortex

Single photon emission computed tomography with technetium-99m-d, l-hexamethylpropyleneamineoxime was used to assess variations in regional cerebral blood flow during temporary clipping in the course of intracranial aneurysm surgery and during the postoperative period in 20 patients, 14 of whom underwent temporary clipping. Of these 14 patients (Group A), 9 had aneurysms of the anterior communicating artery, 2 had aneurysms of the middle cerebral artery, and 3 had aneurysms of the carotid siphon. Temporary clips were applied, according to the site of the lesion, on A1, on the trunk of the middle cerebral artery, or on the trunk of the internal carotid artery. The occlusion time ranged from 2 to 31 minutes. The six patients who did not undergo temporary clipping served as controls (Group B), as follows: three had aneurysms of the posterior communicating artery, one of the anterior communicating artery, one of the middle cerebral artery, and one of the internal carotid artery. All patients were investigated with cerebral single photon emission computed tomography preoperatively, perioperatively, and postoperatively. In all the patients of Group A, the preliminary results of the study show a sharp fall in the perfusion of the territories of the temporarily clipped parent vessel and practically a complete recovery within 2 to 7 days of surgery, with no significant neurological symptoms. No similar disturbance of perfusion was found in the patients of Group B.

Topics: Adult; Aged; Brain; Brain Damage, Chronic; Brain Ischemia; Carotid Artery Diseases; Carotid Artery, Internal; Female; Humans; Intracranial Aneurysm; Intraoperative Complications; Male; Middle Aged; Monitoring, Intraoperative; Organotechnetium Compounds; Oximes; Postoperative Complications; Regional Blood Flow; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

The dynamics of leukocyte infiltration in human cerebral ischemia were studied using technetium-99m hexamethylpropyleneamine oxime (99mTc HMPAO)-labeled leukocyte brain single-photon emission computed tomography (SPECT).. Twenty-two patients diagnosed as having hemispheric ischemic stroke were examined with 99mTc HMPAO brain SPECT for cerebral blood flow study and 99mTc HMPAO-labeled leukocyte brain SPECT for the study of leukocyte infiltration. Three patients with chronic hemispheric ischemic stroke received one examination. Nineteen patients with acute hemispheric ischemic stroke received their initial examination within the first after onset. Follow-up examinations were performed at intervals of 1-3 weeks whenever possible.. In patients with chronic hemispheric ischemic stroke, leukocyte infiltration was not seen in areas of perfusion defect. In patients with acute hemispheric ischemic stroke, leukocyte infiltration was seen in areas of perfusion defect during the acute stage, which persisted for no less than 5 weeks after onset and then declined.. A new method to study and monitor the process of leukocyte infiltration in acute cerebral ischemia using 99mTc HMPAO-labeled leukocyte brain SPECT is described. This method shows that leukocyte infiltration in acute hemispheric ischemic stroke is a dynamic process that persists for no less than 5 weeks and then declines.

Topics: Acute Disease; Aged; Brain Ischemia; Cerebral Arteries; Cerebrovascular Circulation; Female; Humans; Leukocytes; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

A 76-year-old, right-handed man developed posttraumatic dural arteriovenous fistula (DAVF) involving the superior sagittal sinus. He developed slow but progressive intellectual deterioration and gait disturbance after a minimal head trauma. Cerebral angiography demonstrated a DAVF of the superior sagittal sinus with sinus thrombosis supplied by branches of the bilateral external carotid arteries, and a DAVF of the right sigmoid sinus supplied by the right occipital artery. Selective embolization was carried out. He showed marked improvement on neuropsychological testing, especially on test items which are supposed to tap functions of the right cerebral hemisphere which showed an improved cerebral blood flow. We concluded that the intellectual impairment of our patient was caused by cerebral hypoperfusion, especially of the right cerebral hemisphere.

Topics: Aged; Arteriovenous Fistula; Brain Ischemia; Cerebral Angiography; Cerebral Cortex; Dementia, Vascular; Dominance, Cerebral; Dura Mater; Embolization, Therapeutic; Head Injuries, Closed; Humans; Male; Mental Recall; Neurologic Examination; Neuropsychological Tests; Organotechnetium Compounds; Oximes; Psychomotor Performance; Regional Blood Flow; Sinus Thrombosis, Intracranial; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cross-clamping of the carotid artery during carotid endarterectomy implies a risk of developing an ischaemic insult. To evaluate the effects of carotid artery occlusion on cerebral blood flow (CBF), both hemispheric and regional CBF (rCBF) were investigated using intravenously (i.v.) administered 133Xenon with 3 min clearance recording time for two-dimensionally (hemispheric CBF) and 99m-technetium-hexamethylpropylene amine oxime (99mTC-HMPAO) for three-dimensionally single photon emission computed tomography (SPECT) measurements (rCBF). Thirteen patients scheduled to undergo carotid endarterectomy anaesthetised with fentanyl/isoflurane participated in the study. Preoperative evaluation included investigation of rCBF with SPECT in all participants. Two intraoperative 133Xe CBF measurements were performed in each patient, before and after occlusion of the carotid artery. The preoperative rCBF measurement constituted the reference, for technical reasons, for the intraoperative investigations of rCBF during cross-clamping, which was completed immediately after the hemispheric measurements. The increase in preoperative risk evaluation as described by Sundt et al. and modified by Cho et al. corresponded excellently to a decrease in hemispheric CBF due to cross-clamping. A significant decrease in rCBF (p < 0.005) was present between patients with high and low preoperative risk score for the region of the middle cerebral artery. In this region, a correlation between decrease in rCBF and corresponding decrease in hemispheric CBF was also present. The present study demonstrates that the vascular regions of the ipsilateral middle cerebral artery are the most vulnerable vascular area during cross-clamping in individuals with high preoperative risk score.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Aged; Blood Flow Velocity; Brain; Brain Ischemia; Cerebral Infarction; Endarterectomy, Carotid; Female; Humans; Intraoperative Complications; Male; Middle Aged; Models, Theoretical; Monitoring, Intraoperative; Organotechnetium Compounds; Oximes; Regional Blood Flow; Retrospective Studies; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

58 patients with recent transient or permanent neurologic deficits of with proven carotid stenoses were examined by dynamic CT at the level of the internal capsule. In the presence of cerebral infarcts there was marked delay in the time/density curve with reduced peaks. Abnormal perfusion could be demonstrated by early examinations before definite morphological changes were seen. With transient ischaemic attacks there were no significant changes in perfusion; in the presence of carotid stenoses the results were variable. The perfusion abnormalities in the hemispheres shown by dynamic cranial CT could be confirmed to some extent by 99mTc-HMPAO-SPECT.

Topics: Adult; Aged; Aged, 80 and over; Brain Ischemia; Cerebral Infarction; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Fifteen patients with symptoms of cerebral ischaemia and angiographically confirmed unilateral stenoses or occlusions of the extracranial internal carotid artery (ICA) and 20 controls were studied by a 2 MHz transcranial Doppler (TCD) at rest and after stimulation with 1 g acetazolamide i.v., a cerebral vasodilator. In addition, the patients underwent 99mTc-HM-PAO-Spect measurement of regional cerebral blood flow (rCBF) at rest and after stimulation with 1 g acetazolamide. In 10 patients with ICA stenoses greater than 80% or occlusions, time-mean velocity (Vmean) increase and pulsatility index (PI) decrease in the postobstructive middle cerebral artery (MCA) as well as the increase of the ipsilateral rCBF were reduced in comparison with the contralateral side. The remaining 5 patients showed a normal Vmean increase and PI decrease in TCD.

Topics: Acetazolamide; Brain Ischemia; Carotid Artery, Internal; Carotid Stenosis; Echoencephalography; Humans; Organotechnetium Compounds; Oximes; Reference Values; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Permanent occlusion of the internal carotid artery may be required for en bloc resection of a neck tumor or to treat certain aneurysms. The risk of ischemic infarct is usually assessed with carotid balloon test occlusion and concurrent distal arterial pressure measurement. However, up to 20% of patients who tolerate the test occlusion have delayed neurologic sequelae. We propose enhanced MR imaging and hexamethylpropyleneamine oxime (HMPAO) scintigraphy to detect subclinical signs of ischemia and hypoperfusion as adjuncts to the balloon test occlusion to identify patients at risk for delayed sequelae.. We prospectively examined 12 patients referred for balloon test occlusion of the carotid artery. Serial measurements of distal occluded internal carotid pressure were recorded. 99mTc-HMPAO was injected IV after 2 min of asymptomatic test occlusion, and single-photon emission computed tomographic (SPECT) data acquisition was done 1-6 hr later. Contrast-enhanced MR imaging was performed 1-8 hr after completion of the 30-min test occlusion. Signs of decreased perfusion or ischemia on these tests were compared with the mean distal arterial pressure and neurologic status of the patient during test occlusion.. Seven (58%) of 12 patients had abnormal findings on HMPAO scintigraphy or contrast-enhanced MR imaging. Only one patient had neurologic deficits that corresponded to abnormal MR enhancement. The other 11 patients (92%) remained asymptomatic during the 30-min test occlusion. Of these 11 asymptomatic patients, five (45%) had areas of decreased perfusion on scintigraphy and three (27%) had abnormal MR contrast enhancement suggesting residual focal ischemia as a result of the test occlusion. Mean arterial pressures in the distal occluded artery did not correlate well with the imaging results.. HMPAO scintigraphy can show clinically silent areas of decreased perfusion, while enhanced MR shows signs of acute ischemia (i.e., significant hypoperfusion) associated with asymptomatic balloon test occlusion. Theoretically, such patients would be at increased risk for permanent sequelae after permanent carotid occlusion.

Topics: Adult; Aged; Brain; Brain Ischemia; Carotid Artery, Internal; Catheterization; Cerebrovascular Circulation; Collateral Circulation; Female; Head and Neck Neoplasms; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Organotechnetium Compounds; Oximes; Postoperative Complications; Prospective Studies; Risk Factors; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The ictal increase of regional cerebral blood flow has yet to be fully utilised in the investigation of focal seizures. Although single photon emission tomography (SPECT) is being increasingly used in the localisation of epileptic foci, the evolution and time courses of the peri-ictal perfusion changes have yet to be clarified. We performed serial SPECT studies in the interictal, ictal and immediate postictal states in 12 patients with refractory temporal lobe epilepsy to define the patterns and duration of peri-ictal cerebral blood flow changes. Visual analysis showed a constant pattern of unilateral global increases in temporal lobe perfusion during seizures which suddenly switched to a pattern of relative mesial temporal (hippocampal) hyperperfusion and lateral temporal hypoperfusion in the immediate postictal period. Quantitative analysis confirmed the visual assessment. Lateral temporal cortex ictal/normal side to side ratios were increased by mean 35.1% (95% confidence interval 21.8% to 48.4%) more in the ictal studies than in the interictal studies and mesial temporal cortex ratios increased by mean 30.8% (22.4% to 39.2%). In the postictal state, however, lateral temporal ratios were reduced by mean 7.7% (-15.8% to 0.4%) compared with interictal values, whereas mesial temporal perfusion was maintained compared with the interictal studies. These observations provide critical information for interpreting scans which can be used in the localisation of epileptic foci. This postictal switch in blood flow patterns may reflect the underlying metabolic processes of neuronal activation and recovery and have implications for understanding the neurobiology of human epileptic seizures.

Topics: Basal Ganglia; Brain; Brain Ischemia; Cerebral Cortex; Dominance, Cerebral; Electroencephalography; Epilepsy, Temporal Lobe; Evoked Potentials; Hippocampus; Humans; Monitoring, Physiologic; Organotechnetium Compounds; Oximes; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Three patients with large carotid aneurysms were treated by parent artery occlusion with detachable balloons. Of these, 2 had intracavernous carotid artery aneurysms and one had a carotid-ophthalmic aneurysm. All patients underwent a formal balloon occlusion test and tolerated it well. One patient with a carotid-ophthalmic aneurysm, however, developed postoperative ischemic effects. This case was that of a 55 year-old female with right visual disturbance. Her middle cerebral artery flow had been compromised during test occlusion under induced hypotension. Although initially intact after balloon occlusion, she was found to be hemiplegic 24 hours later. She subsequently developed multiple small infarcts which were shown on MRI and which corresponded exactly to the previously demonstrated region of decreased flow during testing. This ischemic complication is possibly due to hypoperfusion, but embolism from the thrombosed aneurysm can not be denied. To prevent these complications, an extracranial-intracranial artery anastomosis prior to parent artery occlusion should be considered if the preoperative 99mTc-HMPAO SPECT shows a compromised cerebral blood flow. In addition to this, postoperative anticoagulant therapy should be given even if test occlusion was well tolerated clinically.

Topics: Brain Ischemia; Carotid Artery Diseases; Carotid Artery, Internal; Catheterization; Cerebrovascular Circulation; Female; Humans; Intracranial Aneurysm; Middle Aged; Organotechnetium Compounds; Oximes; Radionuclide Imaging; Technetium Tc 99m Exametazime

Brain perfusion was studied interictally with 99mTc-HM-PAO SPECT in 47 adult patients with partial epilepsy and normal brain CT. Epilepsy was classified as secondarily generalized in 24 patients, as complex partial in 17 patients and as simple partial in 6 patients. In 24 patients good seizure control was not achieved as these patients had a median number of 78 seizures during the preceding month, while in the rest of the patients seizure control was relatively good (less than 6 seizures during preceding month). Local brain hypoperfusion was observed in 41 or 87% of the patients. Hypoperfusion was located close to the EEG foci in 76% and equally often with temporal and frontal foci. Hypoperfusion and the EEG focus were located on the same side in 83%. Hypoperfusion was more frequent in secondarily generalized epilepsy and simple partial epilepsy than in complex partial epilepsy. Left-sided hypoperfusion was especially associated with complex partial epilepsy. It is likely that the significant epileptogenic brain area was revealed in patients with SPECT focus and EEG focus in the same brain area. In one of our patients MRI showed a small temporal lesion which on successful removal was identified as a low-grade oligodendroglioma. Abnormalities of regional brain uptake of HM-PAO demonstrated by SPECT in patients with partial epilepsy and normal brain CT give further information about pathophysiology in partial epilepsy; this may be of use both for selecting appropriate therapy and in presurgical localization of foci.

Topics: Adult; Brain; Brain Ischemia; Cerebral Cortex; Dominance, Cerebral; Electroencephalography; Epilepsies, Partial; Epilepsy, Complex Partial; Female; Humans; Male; Organotechnetium Compounds; Oximes; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

We converted an absolute value of 133Xe-CBF (initial slope index, ISI) to the three dimensional CBF-SPECT using the intravenous 133Xe injection technique and 99mTc-HMPAO SPECT according to the microsphere model (method A), and the three compartment model described by Lassen et al. (method B): [formula: see text] [formula: see text] where f = flow in the region of interest (ROI), fr = flow in the reference region, C = count density of 99mTc-HMPAO SPECT in the ROI, Cr = count density of 99mTc-HMPAO SPECT in the reference region, and alpha = conversion to clearance ratio of HMPAO. We used alpha value of 1.5, and the whole cerebrum as a reference region. Four asymptomatic subjects and 15 patients with ischemic cerebrovascular disease were entered the study. In method A, excellent correlation was seen between ISI and SPECT-CBF in both of the cerebral hemisphere (r = 0.993; p < 0.001, n = 38) and the cerebellar hemisphere (r = 0.901; p < 0.001, n = 38). When back diffusion of HMPAO was corrected by method B, correlation coefficient of SPECT-CBF with ISI was equivalent to that in method A in the cerebrum (r = 0.978; p < 0.001, n = 38), while the correlation coefficient ih the cerebellum was lowered (r = 0.726; p < 0.001, n = 38) although high flow to low flow ratio was increased. Reproducibility of rCBF assessed 1 week apart from the first CBF-SPECT was highly reproducible in all of the brain regions; correlation coefficient ranged from 0.757 to 0.910 with a mean correlation coefficient of 0.834 (n = 11). The slope and intercept of the linear regression line between 2nd rCBF versus 1st CBF were 0.889 (range, 0.791-1.141) and 5.5 (range, -9.1-13.4), respectively. Regional CBF measured by method B was approximately 20% increase from that measured by method A. However, there was no significant difference in the reproducibility of rCBF between the two methods. Our results indicate that rCBF can be simply and noninvasively quantified using 99mTc-HMPAO SPECT and absolute unit of CBF measured by 133Xe injection technique. SPECT-CBF offers high resolution images and may be applicable for various cerebrovascular disorders in routine clinical use.

Topics: Adult; Aged; Aged, 80 and over; Brain Ischemia; Cerebrovascular Circulation; Female; Humans; Injections, Intravenous; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Xenon Radioisotopes

Brain SPECT perfusion studies in patients with cerebral stroke may be useful to evaluate distant perfusion abnormalities.. 99mTc-HMPAO brain SPECT studies were performed in 17 patients with ischemic lesions in the basal ganglia and/or internal capsule demonstrated by NMR. Regions of interest were adjusted in representative transverse slices to the vascular territories of the anterior, middle, posterior and communicating cerebral arteries.. Patients with ischemic lesions in the right basal ganglia showed increased cerebral perfusion in the left middle artery territory (0.95 +/- 0.13 versus 0.80 +/- 0.06; p = 0.0365). Patients with ischemic lesions in the left basal ganglia showed increased perfusion in the right anterior artery territory (0.93 +/- 0.09 versus 0.82 +/- 0.09; p = 0.0464), in the left anterior artery territory (0.93 +/- 0.09 versus 0.83 +/- 0.14; p = 0.0464), in the left middle artery territory (0.92 +/- 0.09 versus 0.78 +/- 0.05; p = 0.0079) and in the left posterior artery territory (1.05 +/- 0.14 versus 0.90 +/- 0.09; p = 0.036). Patients with ischemic lesions in the right internal capsule showed increased perfusion in the right posterior artery territory (0.95 +/- 0.11 versus 1.10 +/- 0.18; p = 0.0431).. These results show the presence of delayed luxury perfusion phenomena in regions distant from the ischemic site.

Topics: Aged; Aged, 80 and over; Brain; Brain Ischemia; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

We report the SPECT, CT and CW Doppler findings in a series of 117 patients with cerebral ischemic lesions and correlate them with the clinical findings. SPECT-PAO proved to be more sensitive in localizing focal lesions than CT, which in 50% of the cases was normal or yielded an image of cerebral atrophy. In the latter cases CW Doppler ultrasound on the supraaortic trunks showed changes, circumscribed or diffuse. On the CW Doppler and SPECT evidence we consider that the CT image of cerebral atrophy may denote an alteration of the cerebral blood flow and metabolism and should be assessed in this light in the diagnosis and prognosis of cerebral ischemic lesions.

Topics: Adult; Aged; Atrophy; Blood Flow Velocity; Brain; Brain Ischemia; Cerebral Angiography; Cerebrovascular Disorders; Evaluation Studies as Topic; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Organotechnetium Compounds; Oximes; Subtraction Technique; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Ultrasonography

To assess the sequential changes seen in cerebral blood flow using Single Photon Emission Computed Tomography with 99mtechnetium-hexamethylpropylene amine oxime (99mTc-HMPAO SPECT) in acute ischaemic stroke, 35 patients were prospectively studied from June 1990- to March 1991. Scans were performed during the acute phase (1-7 days), sub-acute phase (8-21 days) and chronic phase of stroke (greater than 1 month). Nine patients underwent scans in all 3 phases, 15 patients had 2 scans, and 11 patients had one scan. The majority of infarcts were in the middle cerebral territory (15 patients), while 4 infarcts were in the posterior cerebral territory and two in the anterior cerebral territory. There was a total of 4 lacunar infarcts. Image analysis was by visual inspection and by semiquantitation using homologous regions of interest in opposite hemispheres. SPECT in the acute phase identified the final vascular territory affected in 19 of 27 patients. There were 8 patients in whom early SPECT predicted the vascular territory as seen on late CT scan when the early CT scan was normal. Hyperaemia or reperfusion in the involved vascular territory was identified in 10 patients on scans performed during the sub-acute phase. Late SPECT scans showed perfusion defects greater than the infarct size seen on CT scan in the majority of patients. In all cases, the perfusion defect on the late SPECT scan was equal to or larger than the defect seen on the acute or sub-acute scan. Crossed cerebellar diaschisis was identified in 8 patients, and cortical/subcortical diaschisis in one patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acute Disease; Adult; Aged; Aged, 80 and over; Brain Ischemia; Chronic Disease; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Using single photon emission computed tomography (SPECT), cerebral blood flow was studied in eight patients with gradual deterioration in the level of consciousness after subarachnoid haemorrhage. Four had cerebral ischaemia and four had acute hydrocephalus. In patients with cerebral ischaemia, single photon emission computed tomography scanning showed multiple regions with decreased uptake of technetium-99M labelled d,l-hexamethyl-propylene amine oxime (99mTcHM-PAO) mainly in watershed areas. In patients with acute hydrocephalus, decreased uptake was seen mainly in the basal parts of the brain: around the third ventricle, around the temporal horns of the lateral ventricles, and in the basal part of the frontal lobe. After serial lumbar puncture, there was improvement of the uptake of 99mTc HM-PAO in these basal areas in three (convincingly in two and slightly in the other) of the four patients accompanied by clinical improvement in these three patients. These results suggest that patients with acute hydrocephalus and impaired consciousness after SAH, in contrast to patients with cerebral ischaemia, have decreased cerebral blood flow predominantly in the basal parts of the brain.

Topics: Acute Disease; Brain Ischemia; Cerebrovascular Circulation; Follow-Up Studies; Humans; Hydrocephalus; Intracranial Aneurysm; Organotechnetium Compounds; Oximes; Spinal Puncture; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Topics: Acetazolamide; Adolescent; Adult; Aged; Brain; Brain Ischemia; Cerebral Infarction; Cerebrovascular Circulation; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Polyneuropathies; Subtraction Technique; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Although the blood flow tracer hexamethylpropyleneamine oxime is now widely used for cerebral blood flow mapping using single-photon emission computed tomography, its uptake into acutely ischemic brain has not been well studied. We performed a double-label autoradiographic study in which 99mTc-hexamethylpropyleneamine oxime uptake was compared with [14C]iodoantipyrine-derived cerebral blood flow 0.5, 24, and 72 hours after middle cerebral artery occlusion in 11 rats. We noted excellent correspondence between iodoantipyrine and hexamethylpropyleneamine oxime autoradiograms at all times with both simultaneous tracer injection and 30-minute separation of tracer injections. When the ischemic and hyperemic areas were measured from the same brain section using the two different tracers, hexamethylpropyleneamine oxime underestimated the iodoantipyrine-derived areas by less than 1% (95% confidence interval -2.9% to 2.3%). The maximum discrepancy (-19%) was seen at high flows. When the two tracers were injected separately, the uptake of hexamethylpropyleneamine oxime was not linear compared with iodoantipyrine-derived cerebral blood flow, but the relation became linear after the Lassen correction factor was applied. Hexamethylpropyleneamine oxime uptake thus accurately represents cerebral blood flow 0.5-72 hours after acute cerebral ischemia.

Topics: Animals; Antipyrine; Autoradiography; Brain Ischemia; Brain Mapping; Carbon Radioisotopes; Cerebral Arteries; Cerebral Cortex; Male; Organotechnetium Compounds; Oximes; Rats; Rats, Inbred Strains; Regional Blood Flow; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

Early diagnosis of acute cerebral ischaemia is still unsatisfactory, because X-ray computed tomography (CT) does not reveal the site and extent of hypoperfusion within the first 24 h. Single photon emission computed tomography (SPECT) using 99mTc-hexamethylpropylene amine oxime (HMPAO) may offer earlier information, since the distribution of HMPAO follows the actual cerebral perfusion pattern. We therefore investigated 53 patients suffering from acute cerebral ischaemia (10 with transient ischaemic attacks, 9 with prolonged ischaemic reversible neurological deficits, 34 with completed stroke). SPECT and CT examinations were performed on days 1, 3, and 14. On day 1, SPECT revealed hypoperfused areas in 42 patients, whereas CT showed hypodensities only in 5. The sensitivity of SPECT was higher in cortical compared with subcortical ischaemia. In patients suffering from reversible neurological deficits SPECT normalized in the follow-up, corresponding to clinical improvement. In completed stroke, SPECT demonstrated variable perfusion patterns with hypo-, normo-, and hypoperfused areas on day 3 and especially on day 14. In contrast to CT, HMPAO SPECT leads to early diagnosis of cerebral ischaemia, in particular within the cerebral cortex.

Topics: Aged; Brain Ischemia; Cerebellum; Female; Follow-Up Studies; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Prospective Studies; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Fifty patients suffering from cerebral ischemic attacks, transient or not, were studied with both 99mTc HM-PAO single photon emission computed tomography (SPECT) and computed tomography (CT). In 31 patients both SPECT and CT showed pathologic areas, the max diameters of which were measured on CT images and SPECT orbitomeatal reconstructed sections, and then compared. We observed that: only SPECT images are positive for pathologic conditions in transient ischemic attacks and in the very early phases of infarctions; in recent infarctions (less than 15 days earlier) both SPECT and CT scans are positive but SPECT lesion areas are greater than CT ones; pathologic areas, with clear-cut outlines, having the same dimensions on both CT and SPECT images, are supposed to result from old static infarctions. A persistent perilesional hypoactive area on SPECT images means, in our opinion, a hypoperfusional area liable to new vascular troubles; in which case, medical/surgical therapy seems necessary.

Topics: Adult; Aged; Aged, 80 and over; Brain Ischemia; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

In a retrospective study the sensitivity of SPECT and CT in detecting changes in cerebrovascular disease is compared, based on a group of one hundred patients. The higher sensitivity of SPECT with regard to right-positive results, especially in TIA and PRIND and the markedly lower number of false-negative results are underlined and discussed. The fact that both methods reveal only a slight sensitivity regarding the detection of changes in the basal regions of the brain is also pointed out, with SPECT proving to be the more sensitive of the two methods.

Topics: Adult; Aged; Brain; Brain Ischemia; Cerebrovascular Disorders; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

We studied brain cortical radioactive tracer activity in a consecutive series of nine patients with acute hemispheric ischemic stroke at their first cerebral ischemic stroke at their first cerebral ischemic episode. Results from N,N,N'-trimethyl-N'- (2-hydroxy-3-methyl-5-[123-I]-iodobenzyl)-1,3 propanediamine-2HCl (four patients) and technetium Tc 99m hexamethylpropyleneamine oxime (five patients) single photon emission computed tomographic studies were compared with x-ray computed tomography (CT) and clinical findings within the first 48 hours, on day 10, and on day 30 after the clinical ictus. Cortical hypoactivity agreeing with the clinical findings was found on all initial scans but not in the follow-up studies. Cortical activity on the affected side in patients with stroke was significantly lower when compared with cortical activity in sex- and age-matched controls (n = 21). Computed tomography (with contrast) was less sensitive in detecting the ischemic lesions. These studies demonstrate that in the acute phase of stroke there is a single photon emission computed tomographic cortical disturbance that agrees with clinical findings, even when computed tomography scan infarction is limited to subcortical structures.

Topics: Adult; Aged; Brain Ischemia; Cerebral Cortex; Female; Humans; Iodobenzenes; Kinetics; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

In 16 patients with reversible symptoms of cerebrovascular disease a HMPAO- and/or IMP-SPECT was performed. 12 of these patients were suffering from TIA, 4 from PRIND. Using HMPAO-SPECT in 8 out of 9 patients with TIA and in 1 of 2 with PRIND a hypoperfusion could be demonstrated; IMP-SPECT showed a pathological pattern in 3 of 5 patients with TIA and in none of 2 patients with PRIND. A semiquantitative evaluation showed a tracer accumulation reduced by 13 +/- 12% (HMPAO) and 8 +/- 7% (IMP), respectively, in the clinically involved hemisphere, compared to the contralateral side. In circumscript SPECT lesions a reduction by 21 +/- 8% (HMPAO) or 17 +/- 7% (IMP) was observed. The interhemispheric ratio from the HMPAO-SPECT showed a significant correlation to that of the 133Xe-rCBF measurement (r = 0.86; p less than 0.001). SPECT was positive in a higher percentage than TCT, Doppler sonography, radioangiography and 133Xe-rCBF measurement. This does not imply a higher specificity or sensitivity, because a slight inhomogeneous SPECT pattern may occasionally be observed even in normal persons.

Topics: Adult; Aged; Amphetamines; Brain Ischemia; Cerebrovascular Disorders; Female; Humans; Iodine Radioisotopes; Iofetamine; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Acute Disease; Aged; Brain; Brain Ischemia; Cerebral Cortex; Cerebral Infarction; Female; Follow-Up Studies; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Prospective Studies; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

A new double tracer autoradiographic method for the sequential evaluation of altered regional cerebral perfusion in the same animal is presented. This method is based on the sequential injection of two tracers, 99mTc-hexamethylpropyleneamine oxime and N-isopropyl-(125I)p-iodoamphetamine. This method is validated in the assessment of brovincamine effects on regional cerebral perfusion in an experimental model of chronic brain ischemia in the rat. The drug enhanced perfusion recovery in low-flow areas, selectively in surrounding areas of infarction. The results suggest that this technique is of potential use in the study of neuropharmacological effects applied during the experiment.

Topics: Amphetamines; Animals; Autoradiography; Brain; Brain Ischemia; Cerebrovascular Circulation; Iodine Radioisotopes; Iofetamine; Male; Organotechnetium Compounds; Oximes; Radionuclide Imaging; Rats; Rats, Inbred Strains; Technetium Tc 99m Exametazime; Vasodilator Agents; Vincamine

In order to confirm the diagnosis and clarify the pathophysiology in the ischemic lesions in brain, 99mTc-PAO SPECT was performed in 42 patients with ischemic cerebral diseases, and the findings on 99mTc-PAO SPECT were compared with those on 123I-IMP or 99mTc-DTPA SPECT, and on X-CT. Furthermore, count ratio of ischemic lesion to normal contralateral region (I/N) was used for the evaluation of the detectability in the lesions on 99mTc-PAO or 123I-IMP SPECT, and less than 0.95 of I/N ratio was defined as the decreased accumulation. The detectability of ischemic lesion in brain with 99mTc-PAO SPECT was 80%, which was superior to that (60%) of LDA on X-CT. Especially, 99mTc-PAO SPECT was useful in cases which were examined early after the onset of the attack. On the other hand, 123I-IMP SPECT showed the best result (88%) in the detectability, and furthermore I/N ratio on 123I-IMP SPECT was lower than that on 99mTc-PAO SPECT. In the delayed phase on 123I-IMP SPECT the redistribution was observed in 30%, while on 99mTc-PAO SPECT it was done in none of them. The accumulation of 99mTc-DTPA in brain was found in 6 of 14 cases (43%), and 2 cases among them also showed the accumulation of 99mTc-PAO in the ischemic lesion. In such cases the destruction of BBB might be considered as the cause of the accumulation of 99mTc-PAO. Thus, 99mTc-PAO SPECT was thought to be useful method in clinical studies of the ischemic cerebral diseases.

Topics: Amphetamines; Brain Ischemia; Female; Humans; Iodine Radioisotopes; Iofetamine; Male; Organotechnetium Compounds; Oximes; Pentetic Acid; Technetium Tc 99m Exametazime; Technetium Tc 99m Pentetate; Tomography, Emission-Computed, Single-Photon

Although the distribution of [99mTc]hexamethylpropyleneamine oxime (HM-PAO) in the brain is said to be in a flow-related manner without temporal change, we present cases with leakage of [99mTc]HM-PAO (filling out phenomenon) in the delayed image of brain single photon emission computed tomography (SPECT) and clarify its clinical significance. The filling out phenomenon was observed in seven out of 21 cases of cerebrovascular disease and four cases of arteriovenous malformation. The leakage of [99mTc]HM-PAO was also confirmed by visual and semiquantitative analysis. In the pharmacokinetics of [99mTc]HM-PAO in the blood, the percent dose of plasma fraction at 4 hr was reduced to 54% of activity at 30 min. The percent dose of brain blood could be predicted as 3.36%/1 at 30 min and 2.35%/1 at 4 hr after correction with the hematocrit of the brain. The filling out phenomenon of [99mTc]HM-PAO was attributed to a significant reduction of blood activity of [99mTc]HM-PAO in the plasma. Since the initial image might mask reduced rCBF with an increase of rCBV, the late image would have an advantage in accurately evaluating rCBF from the clearance of [99mTc] HM-PAO bound to the plasma. Therefore, the filling out phenomenon of [99mTc]HM-PAO in late images of brain SPECT could show the area of mild cerebral ischemia accompanying cerebral vascular reserve.

Topics: Aged; Brain; Brain Ischemia; Female; Humans; Male; Middle Aged; Organometallic Compounds; Oximes; Scintillation Counting; Technetium; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed

A combined measurement of regional cerebral blood flow (r CBF) and volume (r CBV) by SPECT was performed in 15 patients with ischaemic cerebral infarction. For measurement of r CBF 99mTc-HMPAO was used, and for r CBV 99mTc-labelled red blood cells. Patients with acute or subacute cerebral infarction (n = 10) showed elevation of r CBV whereas r CBF was either reduced or elevated. Patients with chronic cerebral infarction (n = 5) showed reduction of both r CBF and r CBV. The combined measurement of both r CBF and r CBV by SPECT allows imaging and semiquantitative evaluation of haemodynamic changes in ischaemic cerebral infarction at various stages. The resulting data may be helpful in describing the pathophysiologic compensatory mechanisms.

Topics: Aged; Aged, 80 and over; Blood Volume; Blood Volume Determination; Brain Ischemia; Cerebral Infarction; Cerebrovascular Circulation; Humans; Middle Aged; Organometallic Compounds; Oximes; Sodium Pertechnetate Tc 99m; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Topics: Brain Ischemia; Carotid Arteries; Cerebral Angiography; Humans; Organometallic Compounds; Oximes; Rheology; Technetium Tc 99m Exametazime; Tomography, X-Ray Computed

A new radiotracer of cerebral perfusion, 99mTc-labelled hexamethylpropylene amine-oxime, has been tried in 78 subjects: 6 controls and 72 patients. Qualitatively, the distribution of this tracer in healthy subjects was very much the same as that obtained with a reference method using 133xenon inhalation. Quantitatively, there was no correlation between the real blood flow rate and the normalized cerebral uptake rate. On the other hand, the asymmetry indices obtained in controls (but also in 16 patients) correlated very closely with those obtained with 133xenon. Our first results in acute ischaemic diseases as well as in the evaluation of vasospasm or Alzheimer-like presenile dementia point to wide fields of application for the new compound. Unlike its predecessors, it is always available and will probably be used, without any logistic investment, with the standard equipment of all Nuclear medicine departments.

Topics: Adult; Aged; Aged, 80 and over; Alzheimer Disease; Brain Ischemia; Cerebral Hemorrhage; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Hematoma; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organometallic Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Topics: Brain Ischemia; Cerebrovascular Circulation; Dominance, Cerebral; Epilepsies, Partial; Epilepsy; Epilepsy, Temporal Lobe; Humans; Organometallic Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Local cerebral blood flow (LCBF) images of HMPAO and IMP were directly compared in experimental brain ischaemia in the same rats using a double-tracer autoradiographic technique. Both images were identical in distribution throughout the whole flow areas. However, LCBF values were much lower in HMPAO than in IMP. The results suggest that HMPAO acts as a chemical microembolus in rat brain in both low and high flow areas; however, a quantitative flow measurement is difficult in an HMPAO study.

Topics: Amphetamines; Animals; Autoradiography; Brain Ischemia; Cerebrovascular Circulation; Iodine Radioisotopes; Iofetamine; Male; Organometallic Compounds; Oximes; Radionuclide Imaging; Rats; Rats, Inbred Strains; Technetium Tc 99m Exametazime

Topics: Administration, Inhalation; Adult; Brain Ischemia; Cerebrovascular Circulation; Female; Humans; Male; Organometallic Compounds; Organotechnetium Compounds; Oximes; Radionuclide Imaging; Technetium Tc 99m Exametazime; Tomography, X-Ray Computed; Xenon Radioisotopes

94 subjects, 64 with cerebral ischemia of varying severity and outcome, and 30 controls were studied with technetium-99m hexamethyl propylenamino oxime single photon emission computed tomography in order to evaluate the suitability of this technique in the assessment of cerebral ischemia. Decreased uptake corresponding to the side of clinical symptomatology and/or to CT lesion was found in 93% of the patients with complete stroke and in 28% of the patients with transient ischemic attack. This procedure can be a useful tool in the routine examination of ischemic patients, although the mechanism underlying brain uptake is far from being completely understood and the possible quantitative evaluation of regional cerebral blood flow is worthy of further assessment.

Topics: Brain Ischemia; Humans; Ischemic Attack, Transient; Organometallic Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Three cases with cerebral ischemic symptoms and an intracranial aneurysm are presented. Using [99mTc]hexamethyl-propyleneamine oxime (HM-PAO) single photon emission computed tomography imaging before and during the Matas test, a quantitative measurement method was developed for evaluating brain collateral circulation. The evaluation correlated well with findings of contrast carotid angiography. This noninvasive method seems to be useful for selection of patients for appropriate surgical treatment.

Topics: Aged; Brain; Brain Ischemia; Carotid Arteries; Cerebrovascular Circulation; Collateral Circulation; Constriction; Female; Humans; Intracranial Aneurysm; Male; Organometallic Compounds; Oximes; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Cerebral barotrauma, or the neurological manifestation of the "bends", is a relatively common disease of divers and aviators. To date, however, no-one has succeeded in demonstrating a cerebral or spinal cord lesion in vivo following a decompression incident, despite the presence of definitive clinical signs and symptoms of central nervous system involvement. This paper describes the use of 99Tcm-labelled hexamethylpropyleneamine oxime (99Tcm-HMPAO) with single photon emission tomography in a study of three individuals involved in driving accidents. All three suffered cerebral barotrauma during decompression and all exhibited clinical signs and symptoms of dysbarism to a varying degree. Imaging was performed at time intervals ranging from 2 h to several days following the incidents. The results showed well defined cerebral ischaemic lesions in all three subjects. We conclude that 99Tcm-HMPAO imaging provides a significant advance in locating and demonstrating cerebral lesions following barotrauma and will contribute greatly to our understanding of the pathophysiological processes involved.

Topics: Adolescent; Adult; Barotrauma; Brain Injuries; Brain Ischemia; Embolism, Air; Humans; Intracranial Embolism and Thrombosis; Male; Organometallic Compounds; Oximes; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Single photon emission tomographic imaging of the brain using 99mTc HM-PAO was carried out in patients with a clinical diagnosis of Alzheimer's disease, non-Alzheimer frontal-lobe dementia, and progressive supranuclear palsy. Independent assessment of reductions in uptake revealed posterior hemisphere abnormalities in the majority of the Alzheimer group, and selective anterior hemisphere abnormalities in both other groups. The findings were consistent with observed patterns of mental impairment. The imaging technique has potential value in the differential diagnosis of primary cerebral atrophy.

Topics: Aged; Alzheimer Disease; Atrophy; Brain Ischemia; Dementia; Dominance, Cerebral; Female; Frontal Lobe; Humans; Male; Middle Aged; Organometallic Compounds; Oximes; Supranuclear Palsy, Progressive; Technetium Tc 99m Exametazime; Tomography, Emission-Computed