technetium-tc-99m-exametazime and Ischemic-Attack--Transient

Twenty one cases of proven subarachnoid hemorrhage (S.A.H.) have been analysed in a protocol especially including transcranial doppler (T.C.D.) and 88mTc-H.M.P.A.O. single photon emission tomography (H.M.P.A.O.-S.P.E.C.T.). Seventeen patients were intraoperatively studied. All data were compared with clinical grading, computerized tomography (C.T.) and angiography. S.P.E.C.T. is a quite recent method of measuring and three-dimensional imaging of brain perfusion. It provides important information for the diagnosis of ischemic syndromes in S.A.H. Sixty-two S.P.E.C.T.-scans were performed in twenty one patients. Fifty-eight were abnormal and showed significant abnormalities of brain perfusion varying in extent and severity. In this preliminary study, we set out to validate the clinical use of H.M.P.A.O.-S.P.E.C.T. for the diagnosis of "vapospasm" comparing S.P.E.C.T. data with classical criteria. We propose a classification which allowed us to quantify the ischemic risk in an attempt to adapt the global therapeutic management to hemodynamic data. This method appears to be very sensitive and reliable in this field. It will introduce, if these first results are confirmed, important criteria for the evaluation of patients presenting with S.A.H. as far as prognosis and treatment are concerned, especially in regard to timing of surgery and institution of medical hemodynamic therapy.

Topics: Aneurysm, Ruptured; Cerebrovascular Circulation; Echoencephalography; Female; Humans; Intracranial Aneurysm; Intraoperative Period; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Postoperative Period; Preoperative Care; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The imaging of regional cerebral blood flow (rCBF) by 99mTc-d, 1 HM-PAO and SPECT is described. Its relevance to clinical syndromes, such as stroke, transient ischemic attacks, various forms of dementia, epilepsy, and subarachnoid hemorrhage, is reported.

Topics: Animals; Brain; Cerebrovascular Circulation; Cerebrovascular Disorders; Chemical Phenomena; Chemistry; Dementia; Epilepsy; Humans; Ischemic Attack, Transient; Organometallic Compounds; Organotechnetium Compounds; Oximes; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Although stent assisted angioplasty is an effective treatment for coronary and peripheral arterial disease, its efficacy in intracranial arteriosclerotic disease has not been verified.. To assess the radiographic and clinical outcome of stent assisted angioplasty for symptomatic middle cerebral artery (MCA) stenosis.. We attempted stent assisted angioplasty in 14 patients with symptomatic high grade stenosis (>60%) on the proximal portion of the MCA, who had experienced either recurrent transient ischaemic attacks (TIAs) resistant to medical therapy or one or more stroke attacks. Patient records were analysed for angiographic characteristics, degree of stenosis, pre-procedural regimen of anti-platelet and/or anti-coagulation agents, use of devices, procedure related complications, pre-operative and post-operative single photon emission computed tomography (SPECT) findings, and clinical and radiographic outcomes.. Stent assisted angioplasty was successfully performed in 8 of 14 patients without any serious complications and unsuccessful in 2 of 14 patients due to the tortuous curve of the internal carotid artery siphon. Four patients had complications. Two patients had an arterial rupture; one patient was rescued by an additional stent and balloon tamponade, the other patient died. Complications in the other two patients included thrombotic occlusion and distal thrombosis. Residual stenosis was less than 50% in diameter in all the patients. All eight patients who underwent follow up cerebral angiography had no restenosis. Follow up SPECT showed improved perfusion in the affected MCA territory in all the tested patients with TIA and in one of three stroke patients. Using the modified Rankin Scale at follow up, four of five TIA patients and five of six stroke patients were assessed as functionally improved or having a stable clinical status.. Although the re-stenosis rate in stent assisted angioplasty seems to be better than in primary balloon angioplasty as reported previously, the complication rate is still high. Elective stenting is an alternative therapeutic method for the prevention of secondary ischaemic stroke in stroke patients with MCA stenosis, and seems to be a potentially effective but also hazardous therapeutic technique in patients with recurrent TIAs. This study indicates the need for randomised control trial data of this intervention. Additionally, long term follow up data and additional clinical experience are required to assess the durability of this procedure.

Topics: Adult; Aged; Angioplasty, Balloon; Cerebral Angiography; Cerebral Arterial Diseases; Female; Follow-Up Studies; Humans; Infarction, Middle Cerebral Artery; Intracranial Arteriosclerosis; Ischemic Attack, Transient; Male; Middle Aged; Middle Cerebral Artery; Recurrence; Stents; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

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

Topics: Anesthetics, Local; Brain; Cerebral Arteries; Cerebrovascular Circulation; Female; Homeostasis; Humans; Ischemic Attack, Transient; Middle Aged; Radiopharmaceuticals; Stellate Ganglion; Sympathectomy, Chemical; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Treatment Outcome; Vasodilation

Several clinical conditions, such as deep vein thrombosis, cerebral infarct, pulmonary infarct, skin ulcers, renal failure, and habitual abortion, are thought to be associated with the antiphospholipid syndrome. The authors describe a 32-year-old woman who had characteristics of the antiphospholipid syndrome including increased immunoglobulin G-cardiolipin antibody titers, iliofemoral vein thrombosis, pulmonary embolism, headache, visual disturbances, and habitual abortion. During hospitalization, she suddenly experienced right-sided weakness. A Tc-99m HMPAO brain scan showed the probability of a transient ischemic attack in the left frontotemporal cortex.

Topics: Adult; Antiphospholipid Syndrome; Brain; Female; Femoral Vein; Humans; Iliac Vein; Ischemic Attack, Transient; Pulmonary Embolism; Radionuclide Imaging; Radiopharmaceuticals; Technetium Tc 99m Aggregated Albumin; Technetium Tc 99m Exametazime; Venous Thrombosis

Topics: Arterial Occlusive Diseases; Cerebrovascular Circulation; Humans; Ischemic Attack, Transient; Male; Middle Aged; Posture; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Vertebral Artery

Transient ischaemic attacks (TIAs) are heterogeneous from the clinical, physiopathological, aetiological and prognostic points of view. Single-photon emission tomography (SPET) may influence patient management by helping to define the vascular topography and by suggesting the probable mechanism (embolic or haemodynamic). However, the variables predicting focal regional cerebral blood flow (rCBF) and cerebrovascular reserve (CVR) abnormalities on SPET and their clinical correlation are poorly known. Our objective in this study was to assess the value of rCBF and CVR measured by SPET in a prospective series of 42 patients with recent (within the preceding 30 days) first-ever TIA Two SPET examinations [baseline and post-acetazolamide (ACZ)] were consecutively performed, and region/reference ratios were obtained using an irregular region of interest (ROI) method. Percentages of interhemispheric asymmetry between homologous brain regions were used to identify abnormalities on baseline SPET, and the percentage changes in asymmetry between the baseline and post-ACZ SPET studies were used to identify abnormal responses to the vasodilator stimulus. Mean baseline and test-retest values previously obtained in normals were used as a reference. The relationship of SPET findings with clinical data and results of complementary examinations was assessed. Most patients (98%) had abnormal findings on either baseline (43%), post-ACZ (19%) or both SPET studies (36%). Thus, 33 patients had hypoperfusion on baseline SPET (78.5%, symptom related in 45%). In 23 patients, a poor response to ACZ was found (55%, symptom related in 21.5%). No predictors for rCBF or CVR impairment were found. Most patients with a first-ever TIA episode present focal hypoperfusion on SPET, either with or without correlation with TIA symptoms. Post-ACZ SPET increases the probability of finding cerebrovascular abnormalities, and orients attention towards an haemodynamic compromise. Focal hypoperfusion on SPET should not be viewed as clinically insignificant because it probably reflects previous or ongoing clinical and/or subclinical episodes of cerebral ischaemia.

Topics: Acetazolamide; Aged; Cerebrovascular Circulation; Diuretics; Female; Humans; Ischemic Attack, Transient; Male; Prospective Studies; Radiopharmaceuticals; Risk Factors; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cerebral blood flow (CBF) and cerebral autoregulation have been investigated 24 h after transient focal ischaemia in the rat. Cerebral blood flow was measured autoradiographically before and during a moderate hypotensive challenge, to test autoregulatory responses, using two CBF tracers, (99m)Tc-d,l-hexamethylproyleneamine oxide and 14C-iodoantipyrine. Prior to induced hypotension, CBF was significantly reduced within areas of infarction; cortex (28 +/- 20 compared with 109 +/- 23 mL/100 g/min contralateral to ischaemic focus, P = 0.001) and caudate (57 +/- 31 compared with 141 +/- 32 mL/100 g/min contralaterally, P = 0.005). The hypotensive challenge (mean arterial pressure reduced to 60 mmHg by increasing halothane concentration) did not compromise grey matter autoregulation in the contralateral hemisphere; CBF data were not significantly different at normotension and during hypotension. However, in the ipsilateral hemisphere, a significant volume of cortex adjacent to the infarct, which exhibited normal flow at normotension, became oligaemic during the hypotensive challenge (e.g. frontal parietal cortex 109 +/- 15% to 65 +/- 15% of cerebellar flow, P < 0.01). This resulted in a 2.5-fold increase in the volume of cortex which fell below 50% cerebellar flow (39 +/- 34 to 97 +/- 46 mm3, P = 0.003). Moderate hypotension induced a significant reduction in CBF in both ipsilateral and contralateral subcortical white matter (P < 0.01). In peri-infarct caudate tissue, CBF was not significantly affected by hypotension. In conclusion, a significant volume of histologically normal cortex within the middle cerebral artery territory was found to have essentially normal levels of CBF but impaired autoregulatory function at 24 h post-ischaemia.

Topics: Animals; Antipyrine; Blood Pressure; Brain; Carbon Radioisotopes; Cerebellum; Cerebral Cortex; Cerebral Infarction; Cerebrovascular Circulation; Homeostasis; Ischemic Attack, Transient; Male; Rats; Rats, Inbred F344; Regional Blood Flow; Technetium Tc 99m Exametazime; Time Factors

Topics: Aged; Cerebral Cortex; Embolism; Heart Diseases; Humans; Hyperemia; Ischemic Attack, Transient; Male; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

To report the results of the first 50 consecutive patients with vasospasm secondary to subarachnoid hemorrhage treated with balloon angioplasty after failure of medical management.. Retrospective uncontrolled study of 50 consecutive patients treated with balloon angioplasty between February 1988 and July 1992. Forty-six had objective clinical deterioration despite maximal medical therapy, whereas four were treated on the basis of rapidly accelerating transcranial Doppler velocities and decreased regional blood perfusion detected by technetium-99m-exametazime brain single photon emission computed tomography. All patients had evidence of marked vasospasm demonstrated by angiography. Thirty-two (64%) and 46 (92%) patients underwent angioplasty within 12 and 18 hours, respectively.. Of the patients with clinical evidence of vasospasm-induced ischemia, 28 (61%) showed sustained neurological improvement within 72 hours of angioplasty. Three (6%) patients deteriorated within 72 hours after angioplasty, with two (4%) patients dying immediately after angioplasty as a result of vessel rupture and the other patient's Glasgow Coma Scale score decreasing by 2. Two additional patients in poor condition with Hunt and Hess Grade V at the time of angioplasty subsequently died during hospitalization. Two other patients died as a result of unclipped aneurysms that subsequently bled 4 and 12 days after angioplasty, respectively. The improvement demonstrated clinically, angiographically, and by transcranial Doppler after angioplasty was sustained, with only one patient requiring subsequent angioplasty of a previously dilated segment (total, 170 vessel segments dilated). Two patients developed vasospasm in previously undilated segments.. Timely balloon angioplasty can reverse delayed ischemic deficit caused by vasospasm in patients for whom medical therapy has failed.

Topics: Angioplasty, Balloon; Cerebral Angiography; Equipment Design; Humans; Ischemic Attack, Transient; Radiopharmaceuticals; Retreatment; Retrospective Studies; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Ultrasonography

Cerebral vasospasm is a frequent complication after subarachnoid hemorrhage and contributes to overall morbidity and mortality. Arteriography is the standard test for determining the presence of vasospasm. A retrospective review of 16 patients with cerebral aneurysm was undertaken to assess the sensitivity and specificity of SPECT for diagnosis of vasospasm. Fourteen patients were hospitalized after subarachnoid hemorrhage and 2 patients were hospitalized for elective aneurysmal clipping. The patients' condition on discharge was correlated to clinical and SPECT evidence of vasospasm.. Vasospasm was defined as the new onset of neurological signs and symptoms not explained by rebleed or hydrocephalus. A total of 20 SPECT studies were performed for 16 patients during their admission and 14 of 16 patients had a single angiographic study.. Thirteen of 16 patients had 14 episodes of clinical evidence of vasospasm and 14 SPECT studies were performed in these 13 patients. The sensitivity and specificity of SPECT in this retrospective study were 89% (8/9) and 71% (5/7), respectively. Our small sample of arteriograms yielded in comparison a sensitivity of 67% (2/3) and specificity of 100% (9/9). The one false-negative SPECT study occurred in conjunction with the one false-negative arteriogram in the presence of clinical findings consistent with vasospasm. Three false-positive SPECT studies occurred in 2 patients who had perfusion abnormalities in areas of normal CT findings without clinical or arteriographic evidence of vasospasm. Five of 5 patients who died became unresponsive as a result of clinically presumed vasospasm and 4 of 5 of these patients had diffuse or hemispheric SPECT perfusion defects. Of the 11 patients who survived, none became unresponsive; 1 of 11 had positive diffuse or hemispheric perfusion defects.. SPECT is a sensitive and fairly specific test for corroboration of clinical findings of vasospasm. A negative SPECT study may obviate the need for arteriography. Unresponsiveness is the best predictor of poor outcome; however, hemispheric SPECT perfusion deficits are also associated with poor outcome.

Topics: Cerebral Angiography; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Radiopharmaceuticals; Retrospective Studies; Sensitivity and Specificity; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

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

Cerebral vasospasm after subarachnoid hemorrhage is very common, but it is not universally detectable by transcranial Doppler. SPECT imaging of regional cerebral blood flow with Tc-99m exametazime serves as a complementary test to transcranial Doppler in the evaluation of patients at high risk for vasospasm. The significance of vasospasm, which may be underestimated by TCD, is readily identified with SPECT cerebral perfusion imaging.

Topics: Brain; Female; Humans; Ischemic Attack, Transient; Middle Aged; Organotechnetium Compounds; Oximes; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Ultrasonography, Doppler, Transcranial

Cerebral infarction and prolonged regional hypoperfusion have been described in patients with transient ischemic attacks (TIAs). The aim of this study was to compare the sensitivity of single-photon emission CT (SPECT) with that of brain CT and to evaluate the clinical significance of differentiation of TIA patients with or without focal hypoperfusion.. From a hospital-based population, we studied the SPECT and CT findings in 76 consecutive patients, without a stroke history, who presented with TIA in the carotid artery territory. The recorded variables were the time of SPECT, imaging (<36 or > or = 36 hours), clinical presentation, history of previous TIA(s), duration of the presenting attack (<2 or > or = 2 hours), vascular risk factors, and etiology. We used both visual and semiquantitative analyses for the SPECT evaluation. Acetazolamide challenge was not performed.. The overall SPECT sensitivity was 36% (27/76). When brain CT and SPECT were performed in the same patients, the SPECT sensitivity was significantly higher than that of CT (19/59 [32%] versus 8/59 [14%]; P=.007). The SPECT sensitivity was not dependent on the time of investigation, duration of attacks, history of TIA(s), or the clinical presentation. The vascular risk and etiologic factors were not significantly different between the patients with or without prolonged focal hypoperfusion. Logistic regression did not identify any variable to discriminate the two groups.. Despite its better sensitivity compared with CT, SPECT performed without the acetazolamide test provides no additional clinically useful information on the vascular risk factors and etiology in TIA patients.

Topics: Acetazolamide; Adult; Aged; Aged, 80 and over; Brain; Carotid Arteries; Cerebral Infarction; Cerebrovascular Circulation; Cohort Studies; Female; Humans; Ischemic Attack, Transient; Logistic Models; Male; Middle Aged; Organotechnetium Compounds; Oximes; Prospective Studies; Risk Factors; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Vasodilator Agents

This study examines the topographic profile of reperfusion into ischaemic tissue following reversible middle cerebral artery (MCA) occlusion. Autoradiographic images of both ischaemia and reperfusion were prepared from brain sections following transient ischaemia induced by endothelin-1 application to the exposed MCA in anaesthetised rats. Blood flow changes were assessed using double tracer autoradiography with 99mTc-exametazime during ischaemia (5 min) and 14C-iodoantipyrine during reperfusion (2 h). Following a significant ischaemic insult, reperfusion was relatively homogeneous within MCA territory but incomplete at 2 h. There was evidence for differential reperfusion in the cortex and caudate nucleus, and increased collateral supply from the anterior cerebral artery.

Topics: Animals; Antipyrine; Autoradiography; Cerebral Arteries; Cerebrovascular Circulation; Collateral Circulation; Endothelins; Ischemic Attack, Transient; Male; Organotechnetium Compounds; Oximes; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Technetium Tc 99m Exametazime

The haemodynamic mechanisms responsible for the appearance of paraparetic transient ischaemic attacks in ten patients with childhood moyamoya disease who subsequently underwent bifrontal omental transplantation were investigated. Cerebral perfusion (CP) was measured with 99mTc-hexamethylene-propyleneamine oxime single photon computed tomography prior to and after administration of acetazolamide. Cerebral perfusion was obtained by dividing radioisotope uptake per pixel in regions of interest by that in cerebellum. Haemodynamic reserve was defined as [CP after acetazolamide--CP before acetazolamide]/CP before acetazolamide x 100. Amounts of CP in the anterior portion of the frontal lobe and in the paracentral lobule were 0.70 +/- 0.04 and 0.74 +/- 0.03, respectively, before appearance of the transient ischaemic attacks. The latter was significantly higher than the former (p < 0.0001). Haemodynamic reserves were -11.1 +/- 2.8 and -9.6 +/- 3.0, respectively, at that time. These two parameters were significantly decreased just after paraparetic transient ischaemic attacks and two parameters in the paracentral lobule were more decreased than those in the anterior portion of the frontal lobe. But these increased again after bifrontal omental transplantation in these two regions. In summary, the watershed region was located anterior to the paracentral lobule before appearance of the transient ischaemic attacks, and widened and moved backward to include the paracentral lobule just before their appearance.

Topics: Cerebral Angiography; Cerebral Revascularization; Child; Child, Preschool; Female; Follow-Up Studies; Hemodynamics; Humans; Image Processing, Computer-Assisted; Ischemic Attack, Transient; Male; Moyamoya Disease; Omentum; Organotechnetium Compounds; Oximes; Paralysis; Perfusion; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

For semiquantification of SPECT studies we tried to calculate cerebral 99mTc-HMPAO uptake related to injected dose and estimated brain volume. The method was applied to SPECT investigations of 27 patients who had at least one ischaemic attack and a confirmed 80-100% stenosis of the corresponding internal carotid artery (ICA). Vascular reactivity was tested by parenteral administration of acetazolamide (AZ). Increase in HMPAO uptake after AZ was evident in both hemispheres, although the increase (AZ effect) was significantly lower in the affected hemisphere (+24% versus +28%). No interhemispheric uptake differences were seen in patients with largely normal SPECT studies, although local asymmetries in HMPAO deposition were visible. Patients with low density lesions on CT and with a well-demarcated lesion in the same location on SPECT revealed interhemispheric uptake differences, with lower uptake on the affected side. This was not due solely to alterations in the lesion, but also to reduced HMPAO uptake and AZ effect in the surrounding area. The AZ effect showed no correlation with angiographic findings, indicating no major haemodynamic influence of the ICA stenosis on cerebral hemisphere perfusion. Calculated cerebral HMPAO uptake changes after AZ administration were in good accordance with absolute cerebral blood flow measurements, and made interindividual comparisons possible. However, as changes in the area around an infarct or local reduction in vascular reserve may not be reproduced adequately by uptake calculations, visual inspection is still necessary.

Topics: Acetazolamide; Adult; Aged; Brain; Brain Mapping; Carotid Artery, Internal; Carotid Stenosis; Cerebral Cortex; Cerebral Infarction; Dominance, Cerebral; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Regional Blood Flow; 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

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

Serial brain SPECT imaging was performed on patients after subarachnoid hemorrhage and surgical clipping of intracranial aneurysms. A total of 20 HMPAO scans were performed on 9 patients in whom clinical vasospasm did not develop. Areas of diminished regional cerebral blood flow (rCBF) were found near the operative site in 17 of 20 studies, which did not correlate with the patients' neurologic condition and were suggestive of postoperative edema. Brain SPECT imaging has a potentially valuable role to play in the evaluation of postoperative patients susceptible to vasospasm; however, it is important to be aware of postoperative changes in rCBF that are not related to vasospasm.

Topics: Brain; Brain Edema; Cerebrovascular Circulation; Female; Humans; Intracranial Aneurysm; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Postoperative Complications; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

Topics: Acute Disease; Adult; Blood Flow Velocity; Brain Edema; Cerebral Arteries; Cerebral Infarction; Cerebrovascular Circulation; Cysteine; Humans; Ischemic Attack, Transient; Male; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Xenon

Topics: Brain; Gamma Cameras; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Even during the symptom-free stages, patients with a TIA often experience cerebral blood flow disturbances. In order to evaluate the factors which cause this abnormality, we studied the cerebral blood flow disturbance, anatomy and clinical status in 21 patients after TIAs. The results of 99mTc-hexamethyl-propylene-amine oxime SPECT were compared with CT, cerebral angiogram, cerebrovascular risk factors and clinical findings to determine which factor is most responsible for the hypoperfusion of brain after TIA. The overall sensitivity rates in detecting a lesion were 67% in SPECT and 19% in CT. The hypoperfused area tended to be large in patients who had intracranial, severe stenotic, multiple, or hemodynamically significant arterial lesions on the ipsilateral side. No such relationships were found between other examinations. We conclude that hypoperfusion after TIA essentially reflects a continuous cerebral blood flow disturbance that can be attributed to atherosclerosis of the cerebral arteries, with subsequent embolic and/or hemodynamic cerebral ischemia, although there may be a variety of processes.

Topics: Adult; Aged; Cerebral Angiography; Cerebrovascular Circulation; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Retrospective Studies; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

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

A case with vasospasm of the right anterior cerebral artery induced by hyperventilation is presented. Consecutive Tc-99m HMPAO brain SPECT studies at rest and during hyperventilation greatly contributed to the quantitative evaluation of focal perfusion decrease in conjunction with contrast angiography. This technique seems to be useful for the detection of alterations in regional brain perfusion during short duration intervention.

Topics: Adult; Angiography, Digital Subtraction; Cerebral Angiography; Cerebrovascular Circulation; Electroencephalography; Female; Humans; Hyperventilation; Ischemic Attack, Transient; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cerebral vasospasm is a major determinant of outcome after subarachnoid hemorrhage (SAH). Brain SPECT with 99mTc-HMPAO was obtained before and after cerebral angioplasty in 10 patients with delayed ischemia due to vasospasm. Eight patients had clinically evident neurologic improvement after the procedure. Visual interpretation and an internal-reference (cerebellum), manual, semi-quantitative region of interest (ROI) analysis revealed improvement of regional cerebral blood flow (rCBF) in 9 out of 10. There were disagreements between the visual and ROI analysis in the two that did not improve clinically. For all 10, the average increase per anterior circulation vessel dilated (n = 17) was 8.8% by comparison of the corticocerebellar ratios. For the eight that improved, the average increase was 10.5%. Brain SPECT is valuable for evaluating delayed cerebral ischemia caused by vasospasm after SAH and is useful to document the changes in rCBF induced by angioplasty. It is possible that SPECT may be useful to detect critical reductions in perfusion before clinical deficits develop, thereby offering the potential to identify candidates for early treatment with angioplasty.

Topics: Adult; Angioplasty, Balloon; Brain; Cerebrovascular Circulation; Humans; Ischemic Attack, Transient; Middle Aged; Neurologic Examination; Organotechnetium Compounds; Oximes; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

Even during the symptom-free stages, patients with transient ischemic attacks (TIA) often show cerebral blood flow (CBF) disturbances. For evaluating the factors which cause these abnormalities, we studied CBF and CBF reactivity to acetazolamide (Diamox) using a 99mTc-hexamethylpropyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT). The results from CBF-SPECT were compared with X-ray computed tomography (CT), cerebral arteriogram, clinical characteristics of TIA and cerebrovascular risk factors. The overall sensitivity rates in detecting the lesion were 68% in CBF-SPECT and 9% in CT. The size of the hypoperfused area tended to be wide in patients who had intracranial, severe stenotic or multiple arterial lesions on the ipsilateral side. No such relations were found between CBF and other examinations. Brain hypoperfusion was located in the subcortical region in eight patients; two patients showed a small hypodense lesion on CT which corresponded to the hypoperfusion on SPECT, and three patients showed no arteriographic abnormality. Hypoperfusion in the cortex was seen in seven patients; all patients showed arteriographic abnormality, but no CT abnormality. The severity rating of the vascular stenosis and hypoperfusion, and the incidence of the intracranial lesions were higher in this group than the group with subcotical hypoperfusion. Seven patients showed fixed normoperfusion before and after diamox injection. Two patients with a subcortical small infarction showed fixed hypoperfusion even after diamox injection. Twelve patients showed focal hypoperfusion before diamox with a new filling-in after diamox. Only one patient showed resting hypoperfusion and decreased CBF reactivity to diamox.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acetazolamide; Adult; Aged; Cerebrovascular Circulation; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Risk Factors; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

15 patients with suspected cerebral ischaemia were examined using 99mTc-HM-PAO-SPECT to assess cerebral blood flow. Results obtained from SPECT were correlated with CT and Doppler ultrasound findings. A 3D-display algorithm is proposed to enhance the lesion to non-lesion contrast compared to the standard 2D-image interpretation. In all cases contrast was superior on 3D-display to 2D-display (-0.38 versus -0.09). 3D-display of SPECT-data enhances lesion contrast due to postreconstructive data processing and may improve exact interpretation of cerebral blood flow studies.

Topics: Adult; Aged; Brain; Carotid Arteries; Cerebrovascular Circulation; Evaluation Studies as Topic; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Ultrasonography

Sixty patients were studied for carotid artery disease and were further evaluated with hexamethyl-propyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) both at baseline (with the patient resting) and after administration of acetazolamide (ACZ). Of these 60 patients, 58 (97%) had symptoms and 49 (82%) had stenoses greater than 70% in at least one internal carotid vessel. Nine patients (15%) had symmetric findings on baseline examinations and at SPECT with ACZ. Thirty-two patients (53%) had asymmetric findings on baseline, but in 24 of these patients (75%) additional lesions were observed after ACZ administration. Nineteen patients (32%) had asymmetric findings only after ACZ was administered. HMPAO SPECT with ACZ allows detection of diminished cerebral perfusion reserve that is not found when HMPAO SPECT is performed with the patient at rest. This procedure helps provide an objective evaluation of the hemodynamic effects of carotid stenosis.

Topics: Acetazolamide; Adult; Aged; Aged, 80 and over; Arterial Occlusive Diseases; Carotid Artery Diseases; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Regional cerebral blood flow reduction was measured in 84 patients with CVI using 99mTc-HMPAO-SPECT. 53 patients received 1 g acetazolamide to evaluate cerebrovascular reserve capacity. Differentiating between hemispheric (87%) and vertebrobasilar ischaemia (64%) revealed markedly increased sensitivity for the provocative test with acetazolamide. In 62% of high grade but asymptomatic carotid stenoses a haemodynamic effect was demonstrated with acetazolamide and thereby the indication for surgery was supported.

Topics: Acetazolamide; Aged; Aged, 80 and over; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Using SPECT, the time course of brain uptake was compared between N-isopropyl-p-[I-123]-iodoamphetamine (I-123 IMP) and Tc-99m d,l hexamethyl-propyleneamine oxime (Tc-99m HM-PAO). Of 14 patients with cerebrovascular disease showing areas of the "filling-in phenomenon" (i.e. delayed uptake) with I-123 IMP brain SPECT, 7 exhibited persistent defects with Tc-99m HM-PAO (Group I), and 7 showed early washout after the initial uptake (Group II). The filling-in of I-123 IMP did not always correlate to the washout region of Tc-99m HM-PAO. The temporal changes were also confirmed by semiquantitative analysis. While the filling-in of I-123 IMP was affected by many factors, the washout of Tc-99m HM-PAO was attributed to significant reduction of Tc-99m HM-PAO in the plasma. Delayed imaging of the brain with Tc-99m HM-PAO using SPECT may give a more accurate estimate of regional cerebral blood flow in cerebrovascular disease, because it should be lees effected by cerebral blood volume.

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

We used single-photon emission computed tomography with technetium-99m hexamethylpropylene amine oxime in 18 studies on 13 patients with subarachnoid hemorrhage to determine whether any changes in cerebral blood flow could be correlated with clinical or computed tomographic evidence of delayed ischemia. Among the seven patients without focal neurologic deficits, regional cerebral hypoperfusion was demonstrated in only one who died. Among the 10 patients with aneurysmal subarachnoid hemorrhage, one died before surgery, and six developed postoperative delayed ischemic deficits, of whom two died. Among the patients with angiographically documented aneurysms, regional hypoperfusion correlated with the presence and severity of delayed neurologic deficits, whereas correlative computed tomographic scans showed either early infarction or no relevant abnormality. This technique facilitates early diagnosis of cerebral tissue hypoperfusion due to vasospasm after subarachnoid hemorrhage.

Topics: Cerebral Angiography; Cerebrovascular Circulation; Female; Humans; Image Processing, Computer-Assisted; Intracranial Aneurysm; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, X-Ray Computed

Vasospasm of intracranial vessels is difficult to diagnose on clinical ground alone. Still, a clear diagnosis is important because it can impact on surgical timing; and also because it can help evaluate new treatments. Fifteen patients with sub-arachnoid hemorrhage secondary to aneurysm rupture were submitted to a total of 26 tomographic technetium-99m-hexamethyl-propyleneamine oxime (99mTc-HM-PAO) brain examinations that were correlated with temporally close (generally less than 24 hr) angiography or transmission computed tomography (TCT). Nine of 10 angiographically confirmed episodes of spasm and 6 of 6 infarcts seen on angiography or TCT were correctly diagnosed with 99mTc-HM-PAO. One normal scintigraphic exam was angiographically doubtful, one positive 99mTc-HM-PAO study was normal on angiography (sub-radiologic spasm?), one technically poor scintigraphy was positive for spasm on angiograms, and eight exams were normal for spasm with all modalities. We had agreement between tests in 23 of 26 series of exams (88%) obtained in 15 patients. We think that 99mTc-HM-PAO tomography should be useful for the evaluation of patients with suspected vasospasm.

Topics: Adult; Aged; Cerebral Angiography; Female; Humans; Intracranial Aneurysm; Ischemic Attack, Transient; Male; Middle Aged; Organotechnetium Compounds; Oximes; Radionuclide Imaging; Rupture, Spontaneous; Subarachnoid Hemorrhage; Technetium Tc 99m Exametazime

The authors presented clinical material on cerebral hemodynamics in patients with neurological pathology in suspected tumor vascular cerebral diseases and craniocerebral traumas. Investigation of cerebral microcirculation was performed using a multidetector single-photon emission tomograph "Testoscan" (USSR) after iv administration of 99mTc-hexamethylpropilene-amyloxine. This radiopharmaceutical is good for the evaluation of cerebral perfusion and gives a clinician rich information on cerebral microcirculation.

Topics: Adult; Aged; Cerebrovascular Circulation; Cerebrovascular Disorders; Drug Evaluation; Head; Humans; Intracranial Aneurysm; Ischemic Attack, Transient; Microcirculation; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

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

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 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: Adult; Aged; Cerebral Angiography; Cerebrovascular Disorders; Humans; Ischemic Attack, Transient; Middle Aged; Organometallic Compounds; Oximes; Radiographic Image Enhancement; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, X-Ray Computed; Ultrasonography

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

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

Topics: Alzheimer Disease; Brain; Dementia; Humans; Huntington Disease; Ischemic Attack, Transient; Organometallic Compounds; Oximes; Radionuclide Imaging; Technetium Tc 99m Exametazime

A new radiopharmaceutical, technetium-99m hexamethylpropyleneamine oxime (99mTc-d, 1-HM-PAO), has been reported to cross the blood-brain-barrier and to distribute in brain in proportion to regional blood flow. This study reports brain imaging obtained with 99mTc-d,1 HM-PAO in 20 subjects; seven without evidence of cerebral disease and 13 with cerebrovascular disorders. In 16 patients comparative data were available with N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-iodobenzyl)-1,3-propanediamine ([123I]HIPDM). Technetium-99m-d, 1-HM-PAO is retained sufficiently long to allow single photon emission computed tomography (SPECT) with widely available rotating gamma camera systems. The kinetics demonstrated a rapid brain uptake and prolonged retention of activity in cerebral structures. Good tomographic images are obtained with much higher uptake in gray than in white matter. Blood flow maps are comparable to those achieved with [123I]HIPDM and established strokes were clearly seen, with similar details as in HIPDM studies. Delayed studies showed that the distribution in the brain remained virtually unchanged. Technetium-99m-d, 1-HM-PAO imaging appears particularly promising in routine examination of patients with cerebrovascular disorders.

Topics: Brain; Cerebrovascular Disorders; Evaluation Studies as Topic; Humans; Iodobenzenes; Ischemic Attack, Transient; Oximes; Regional Blood Flow; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed