technetium-tc-99m-exametazime and Arterial-Occlusive-Diseases

Patients with internal carotid artery (ICA) occlusion can demonstrate impaired cerebral vascular reserve (CVR). The detection of CVR using single photon emission CT (SPECT) is nowadays widely accepted as a predictor in the diagnostic pathway in patients considered for cerebral revascularization. Recently perfusion CT (PCT) gained widely acceptance in stroke imaging. The present study was aimed at comparing the results of perfusion CT (PCT) and 99m Tc-HMPAO SPECT with acetazolamide challenge in patients with ICA occlusion.. 13 patients were included in the prospective evaluation. Both PCT and 99m Tc-HMPAO SPECT were performed before and after the administration of acetazolamide. In detail, regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), adapted time to peak (Tmax) and mean transit times (MTT) were compared with SPECT data. -. 99m Tc-HMPAO SPECT demonstrated an impairment of CVR in six patients. A preserved CVR was present in seven patients. All patients with impaired CVR proven by SPECT had a delayed MTT (mean +2.98 s) and a delayed Tmax (mean + 5.9 s), (both p <0.005 compared with the non occluded side). 66% of patients with impaired CVR in SPECT showed a complete correlation of Tmax measurements in PCT with a high positive predictive value (PPV: 88.8%). -. The prospective study demonstrated a highly significant correlation of perfusion parameters as detected by 99m Tc-HMPAO SPECT and the Tmax as detected by PCT in patients with ICA occlusion. Therefore this easy-to-perform technique seems to be an adequate method for the evaluation of cerebral perfusion in patients with ICA occlusion.

Topics: Adolescent; Adult; Aged; Arterial Occlusive Diseases; Blood Volume; Brain Mapping; Carotid Artery, Internal; Cerebrovascular Circulation; Female; Humans; Male; Middle Aged; Perfusion; Regional Blood Flow; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Young Adult

We studied the pre and post-operative perfusion reserve using Diamox 99mTc-HMPAO SPECT in 7 patients with chronic occlusive cerebral arteries and then compared the results with PET. STA-MCA anastomosis was performed on 5 patients, while a carotid endarterectomy was done on 2 patients. The cerebral blood flow, the vascular response to CO2 or Diamox, the oxygen extraction fraction and transit time (CBV/CBF) were measured by PET. In the pre-operative state, the visual evaluations for hypoperfusion area at rest were agreed in 5 out of 7 patients in HMPAO SPECT and PET studies. In the remaining 2 patients, hypoperfusion areas were only detected in the PET study. The pre-operative evaluation of perfusion reserve was agreed in 2 patients. In the remaining 5 patients, 3 patients showed definite positive(++) in PET and positive(+) in HMPAO SPECT, and one patient showed positive (+) in PET and negative (-) in HMPAO SPECT. The post-operative change of hypoperfusion areas was well agreed in HMPAO SPECT and PET studies. However, the change of perfusion reserve was underestimated in HMPAO SPECT compared with PET. In the semiquantitative and quantitative analyses, the count rate ratios (affected/unaffected side) in HMPAO SPECT were apparently higher than those of CBF in PET. The postoperative change of the count rate ratios in HMPAO SPECT were smaller than those of CBF in PET. There was no significant correlation between the change in the ratio of the HMPAO SPECT after the administration of Diamox and the oxygen extraction fraction, and it was thus thought to be impossible to predict the areas with an increased oxygen extraction fraction. Thus, Diamox HMPAO SPECT may underestimate the areas of hypoperfusion or decrease in perfusion reserve when compared with PET. We should consider these limitations in the evaluation of pre and post operative cerebral hemodynamics.

Topics: Acetazolamide; Adult; Aged; Arterial Occlusive Diseases; Cerebral Arterial Diseases; Cerebral Revascularization; Chronic Disease; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon

Topics: Aged; Arterial Occlusive Diseases; Brain Mapping; Carotid Artery, External; Carotid Artery, Internal; Cerebral Angiography; Cerebral Revascularization; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Humans; Male; Middle Aged; Perfusion; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The brain distribution of 9mTc-hexamethylpropyleneamine oxime (HMPAO) correlates with regional brain perfusion, whereas 99mTc-ethyl cysteinate dimer (ECD) reflects not only perfusion but also the metabolic status of brain tissue. We compared 99mTc-ECD single-photon emission CT (SPECT) with 99mTc-HMPAO SPECT early after recanalization by local intraarterial thrombolysis (LIT) in patients with acute embolic middle cerebral artery occlusion. We also assessed the predictive value of 99mTc-HMPAO and 99mTc-ECD SPECT for the development of ischemic brain damage.. 99mTc-HMPAO and consecutive 99mTc-ECD SPECT studies were performed in 15 patients within 3 hours of LIT. The two SPECT studies were obtained independently using a subtraction technique. SPECT evaluation was performed using semiquantitative region-of-interest analysis. Noninfarction, infarction, and hemorrhage were identified by follow-up CT or MR imaging.. Forty-five lesions were identified (21 noninfarctions, 19 infarctions, and five hemorrhages). Regardless of 99mTc-HMPAO SPECT findings, lesions showing isoactivity (count rate densities of 0.9 to 1.1 as compared with the contralateral side) on 99mTc-ECD SPECT were salvaged. Lesions with hypoactivity (values < 0.9) on 99mTc-ECD SPECT developed irreversible brain damage. Hemorrhage appeared in lesions with both hyperactivity (values > 1.1) on 99mTc-HMPAO SPECT and hypoactivity on 99mTc-ECD SPECT.. The brain distribution of 99mTc-ECD in a reperfused area identified by 99mTc-HMPAO SPECT early after recanalization of acute ischemic stroke is dependent on cerebral tissue viability. By combining 99mTc-ECD and 99mTc-HMPAO SPECT, performed within the first few hours of LIT, it is possible to identify patients at risk for hemorrhagic transformation reliably.

Topics: Aged; Arterial Occlusive Diseases; Brain; Cerebral Hemorrhage; Cerebral Infarction; Cysteine; Female; Fibrinolytic Agents; Humans; Injections, Intra-Arterial; Intracranial Embolism; Magnetic Resonance Imaging; Male; Middle Aged; Organotechnetium Compounds; Predictive Value of Tests; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

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

The aim of this study was to correlate the abnormality in cerebral blood volume (CBV) measured by dynamic susceptibility contrast-enhanced MRI with that in cerebral blood flow (CBF) estimated by single-photon emission CT with [99mTc]hexamethylpropylenamine-oxime in patients with acute ischemic stroke.. Nine patients with unilateral occlusion of either the middle cerebral artery or the internal carotid artery (4 men and 5 women; mean+/-SD age, 74.4+/-11.6 years) were studied within 6 hours after stroke onset. The relative CBV (relCBV) and CBF (relCBF) in the lesions were defined relative to the contralateral mirror regions.. In the brain regions with mild (relCBF >/=0.60), moderate (0.401.0) regions was significantly lower than that for hypovolemic (relCBV <1.0) regions in the relCBF range between 0.40 and 0.50 (P<0.02).. In acute ischemic stroke within 6 hours of onset the CBV can be either increased, normal, or decreased, depending on the severity of hypoperfusion. The increased CBV has a protective effect on evolving infarction. Although the CBF is a better predictor of tissue outcome, the CBV measurement may help detect potentially salvageable brain tissue in the penumbra with compromised blood flow.

Topics: Acute Disease; Aged; Aged, 80 and over; Arterial Occlusive Diseases; Blood Volume; Cerebral Angiography; Cerebral Infarction; Cerebrovascular Circulation; Contrast Media; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Multivariate Analysis; Radiopharmaceuticals; Sensitivity and Specificity; 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

Acetazolamide is commonly used with single-photon CT to assess the cerebrovascular reserve in patients with internal carotid artery stenosis or occlusion. In this study we wanted to evaluate the effects of adenosine, a well-known vasodilatatory compound with a short biological half-life, on brain circulation in humans and compare the results with those of acetazolamide.. Acetazolamide (1 g) and adenosine (140 micrograms/kg per minute) were injected intravenously on different days in 6 normal subjects and 6 patients: 4 with unilateral stenosis, 1 with bilateral stenosis, and 1 with complete occlusion of the internal carotid artery. Changes in regional cerebral blood flow relative to that of the cerebellum (cortico/cerebellar ratios) from resting conditions were evaluated by 99mTc-hexamethylpropyleneamine oxime and single-photon emission CT.. The measured blood flow ratios increased significantly in the normal group 20 minutes after acetazolamide injection in several cortical and subcortical regions, as well as at the 4th minute of a 6-minute adenosine infusion. Regional cerebral blood flow ratio values were higher after adenosine than after acetazolamide in both cortical (frontal and parietal) and subcortical (thalamus and basal ganglia) regions. In 4 of the 6 patients the side-to-side asymmetry increased from the basal resting condition after the injection of acetazolamide and even more so after the injection of adenosine.. Adenosine infusion causes vasodilation of cerebral arteries and can be used for the investigation of cerebrovascular perfusion capacity in patients with carotid occlusive disease. One advantage in the use of adenosine over acetazolamide is the possibility of interrupting the test with reversal of clinical symptoms or patient discomfort within a few minutes.

Topics: Acetazolamide; Adenosine; Aged; Arterial Occlusive Diseases; Basal Ganglia; Carotid Artery, Internal; Carotid Stenosis; Cerebellum; Cerebral Arteries; Cerebral Cortex; Cerebrovascular Circulation; Female; Frontal Lobe; Humans; Injections, Intravenous; Male; Middle Aged; Organotechnetium Compounds; Oximes; Parietal Lobe; Technetium Tc 99m Exametazime; Thalamus; Tomography, Emission-Computed, Single-Photon; Vasodilation

In the management of major cerebral artery obstruction, cerebral perfusion reserve is key to introducing cerebral revascularization surgery. The purpose of this study was to evaluate the feasibility of assessing cerebral perfusion reserve by consecutive 99mTc-hexamethyl-propyleneamine oxime (99mTc-HMPAO) SPECT with 5% carbon dioxide (CO2) inhalation.. The CO2 inhalation and consecutive 99mTc-HMPAO SPECT study was performed on 30 chronic ischemic cerebrovascular disease patients with unilateral major cerebral artery obstruction and on 27 patients without. CO2 reactivity was expressed as the percent increase of 99mTc-HMPAO accumulation from the baseline (%Change) and as a constant k' that was the ratio of 99mTc-HMPAO accumulation per 1 mmHg change of end-tidal CO2 tension by exponential curve fitting.. The mean %Change and k' in the middle cerebral artery (MCA) territory on the side without an obstructive lesion or in the cerebellum ranged from 10.0% to 11.1% and from 0.98% to 1.13% per mmHg, respectively. In the MCA territory, an obstructive lesion was noted in 5.9% versus 0.54% per mmHg in the contralateral MCA territory (p < 0.01). Eleven of 30 patients with major cerebral artery obstruction revealed significant asymmetry in the k' value between bilateral MCA territories.. The results showed compromised cerebral perfusion reserve in the obstructed major cerebral artery territory. The present method was proven clinically useful for evaluating cerebral perfusion reserve in patients with unilateral major cerebral artery obstruction.

Topics: Adult; Aged; Arterial Occlusive Diseases; Blood Pressure; Carbon Dioxide; Cerebrovascular Circulation; Cerebrovascular Disorders; Chronic Disease; Female; Heart Rate; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cerebral infarction following internal carotid artery occlusion results from either embolism or inadequate collateral blood flow. Although risk of embolism can be minimized, detecting compromised collateral circulation is more difficult. Cerebral angiography, carotid stump pressures and clinical evaluation during internal carotid artery occlusion are of limited utility. Xenon-133 radionuclide studies and stable xenon computed tomography are not readily available. We evaluated 99mTc-HMPAO SPECT, during temporary carotid artery occlusion, in 20 patients considered for internal carotid artery occlusion. Fourteen demonstrated symmetric cerebral perfusion during occlusion; eleven underwent transient and three had permanent carotid artery occlusion without complications. Five patients had ipsilateral globally decreased perfusion during temporary occlusion. One patient underwent transient occlusion of this vessel and one underwent carotid sacrifice without bypass grafting; both recovered without sequelae. The three remaining patients underwent carotid artery bypass grafting prior to sacrifice of this vessel. One patient with a small focal perfusion defect underwent carotid artery sacrifice without bypass grafting and developed acute neurologic deficits postoperatively. These initial results suggest that symmetric cerebral perfusion during temporary occlusion indicates that internal carotid artery occlusion will be tolerated. Although its implications are not yet well defined, the abnormal study identifies patients potentially at risk for postocclusion complications, thus providing a basis for neurosurgical management.

Topics: Adolescent; Adult; Aged; Arterial Occlusive Diseases; Brain; Carotid Artery Diseases; Carotid Artery, Internal; Cerebrovascular Circulation; Collateral Circulation; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

Insufficiency of collateral supply may lead to low-flow infarcts in severe occlusive cerebrovascular disease. The aim of this study was to evaluate the feasibility of technetium-99m-labeled hexamethylpropyleneamine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) to assess hemodynamic compromise in the anterior circulation.. Cerebral blood flow before and after 1 g acetazolamide was analyzed by 99mTc-HMPAO-SPECT in 21 symptomatic patients with documented extracranial obstructions. SPECT findings were correlated with the results of angiography, transcranial Doppler sonography, and computed tomographic scan.. The acetazolamide-induced increase of cerebral blood flow could be reliably monitored by increase of cerebral 99mTc-HMPAO uptake, which varied between 11.4% and 47.6% in the less-affected hemisphere. Increment of hemispheric side-to-side asymmetry of tracer uptake after drug challenge revealed significant restriction of regional vasoreactivity in 11 patients. Agreement in assessing hemodynamic compromise was reached in 81% of patients with ophthalmic artery collaterals on angiography (p < 0.001), in 76% with low-flow infarcts on computed tomographic scan (p < 0.01), and in 91% with markedly reduced flow velocities on transcranial Doppler (p < 0.0001). One patient developed a low-flow infarct in the area predicted by SPECT during follow up.. We conclude that 99mTc-HMPAO-SPECT with acetazolamide challenge is a useful method for assessment of the adequacy of hemispheric collateral pathways in patients with severe occlusive cerebrovascular disease.

Topics: Acetazolamide; Adult; Aged; Arterial Occlusive Diseases; Cerebral Angiography; Cerebrovascular Disorders; Feasibility Studies; Female; Hemodynamics; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Ultrasonography; Vasodilation

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

Cerebral perfusion through stenosed internal carotid arteries is usually maintained by autoregulation. However, flow reserve may be reduced, suggesting hemodynamically significant stenosis, and such reduction should be improved by carotid endarterectomy. This concept was studied in 20 subjects with unilateral internal carotid artery stenosis (major stenosis greater than or equal to 70%, minor stenosis less than or equal to 50%). Thirteen had experienced recent transient ischemic attacks and seven had no definite focal symptoms. Subjects underwent Tc-HMPAO cerebral SPECT during acetazolamide dysautoregulation before and after internal carotid endarterectomy. Nine (45%) had perfusion defects that improved after surgery, suggesting surgery had improved cerebral flow reserve. Seven had defects that did not improve after surgery. Four had worsened or new defects after surgery, suggesting perioperative infarcts. The relatively large proportion of patients with improved cerebral blood flow reserve after surgery suggests that this technique may have a significant role to play in assessing which patients might benefit from carotid endarterectomy.

Topics: Aged; Arterial Occlusive Diseases; Carotid Artery Diseases; Carotid Artery, Internal; Cerebrovascular Circulation; Endarterectomy; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Radionuclide Imaging; Technetium Tc 99m Exametazime

Topics: Adolescent; Adult; Amphetamines; Arterial Occlusive Diseases; Brain; Cerebrovascular Circulation; Child; Child, Preschool; Female; Humans; Iodine Radioisotopes; Iofetamine; Male; Middle Aged; Moyamoya Disease; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Arterial Occlusive Diseases; Brain; Cerebral Angiography; Cerebrovascular Circulation; Child; Humans; Male; Moyamoya Disease; Organotechnetium Compounds; Oximes; Respiration; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

99mTc-HM-PAO was used to evaluate regional cerebral blood flow in a 26-year-old woman with Moyamoya disease. This patient had an 18-month history of recurrent neurologic deficits and had angiographic evidence of Moyamoya disease. She had used oral contraceptives and cigarettes, but had no other risk factors for stroke. Single photon emission computed tomographic images showed bilateral and asymmetric reductions in blood flow to anterior and lateral brain regions. These findings correlated better with clinical symptomatology and suggested more extensive brain involvement than did computed tomography.

Topics: Adult; Arterial Occlusive Diseases; Cerebrovascular Circulation; Female; Humans; Moyamoya Disease; Organometallic Compounds; Oximes; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, X-Ray Computed

Topics: Arterial Occlusive Diseases; Carotid Artery Diseases; Carotid Artery, Internal; Humans; Male; Middle Aged; Organometallic Compounds; Oximes; Radionuclide Imaging; Technetium Tc 99m Exametazime