No abstract available.
Brain* ; Technetium Tc 99m Exametazime ; Tomography, Emission-Computed, Single-Photon*

PURPOSE: Cerebral blood flow (CBF) reactivity to acetazolamide (ACZ) is useful to select patients with hemodynamic failure. However, it is still a matter of speculation that varying degrees of regional CBF increases after ACZ administration represent the severity or stage of regional hemodynamic failure as assessed by positron emission tomography (PET). We studied to elucidate whether ACZ challenge (123) I-IMP brain single photon emission tomography (SPECT) can accurately grade the severity of regional hemodynamic failure. MATERIALS AND METHODS: Eighteen patients (M: 16, F: 2, average age: 61 years) with unilateral occlusive disease of the internal carotid artery or the trunk of the middle cerebral artery (MCA). Patients underwent (123) I-IMP brain SPECT study with acetazolamide challenge and PET study was carried out within 2 weeks before and after SPECT study. Five healthy volunteers with a mean age of 48 years (range: 28-73 yr, M: 3, F: 2) underwent PET studies to determine normal values. In SPECT study, an asymmetry index (AI) -the percentage of radioactivity of region of interest (ROI) in the occlusive cerebrovascular lesion to the contralateral homologous ROI-was used for numerical evaluation of relative (123) I- IMP distribution. In PET study, regional CBF, oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen (CMRO2) and cerebral blood volume (CBV) values were measured with (15) O-labeled gas inhalation method and the values were used for comparison with AI (AI during acetazolamide challenge-AI of basal study) on the SPECT study. ROIs were classified by severity into three groups (normal, stage I and stage II). RESULTS: Mean values of AI in areas with normal, stage I and stage II hemodynamic failure were 6.25+/-7.77% (n=107), -10.38+/-10.41% (n=117) and 13.30+/-10.51% (n=140), respectively. AI significantly differed with each groups (p< 0.05). Correlation between AI and CBF, OEF and CBV/CBF in hemisphere with occlusive cerebrovascular lesion was 0.20 (p< 0.01), -0.28 (p< 0.01) and -0.28 (p< 0.01), respectively. CONCLUSION: We concluded that (123) I-IMP brain SPECT with acetazolamide challenge could determine the severity and stage of regional hemodynamic failure as assessed by PET.
Acetazolamide* ; Blood Volume ; Brain* ; Carotid Artery, Internal ; Healthy Volunteers ; Hemodynamics* ; Humans ; Inhalation ; Middle Cerebral Artery ; Oxygen ; Positron-Emission Tomography ; Radioactivity ; Reference Values ; Tomography, Emission-Computed, Single-Photon