ASSESSMENT OF BENZODIAZEPINE RECEPTORS USING IODINE-123-LABELED IOMAZENIL SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY IN PATIENTS WITH ISCHEMIC CEREBROVASCULAR-DISEASE - A COMPARISON WITH PET STUDY

Background and Purpose [I-123]Iomazenil (IMZ) is a tracer used for sin gle-photon emission computed tomography (SPECT) that has the character istics of selectively binding to central benzodiazepine receptors (BZR ) in the neuron membrane. To determine whether IMZ SPECT provides new information on assessing neuronal damage after ischemic insult to the brain, we compared IMZ SPECT images with the cerebral blood flow (CBF) , cerebral metabolic rate of oxygen (CMRO2), and cerebral metabolic ra te of glucose (CMRGlc) studied by positron emission tomography in the chronic stage of ischemic stroke. Methods Five patients (male mean age , 63.2+/-6.0 years) with ischemic cerebrovascular disease and 6 age- a nd sex-matched normal control subjects were studied. IMZ images obtain ed 180 minutes after injection were analyzed for BZR binding, and thes e images were compared with the CBF, CMRO2, and CMRGlc obtained by pos itron emission tomography in the same perfusion areas both visually an d quantitatively. Results In the visual analysis of data obtained from 4 patients with subcortical infarction, decreased IMZ accumulation wa s observed locally in the overlying normal-appearing cortices of the a ffected hemisphere: where extensive hypoperfusion and hypometabolism w ere seen on the images of CBF, CMRO2, and CMRGlc. The regional relativ e IMZ uptake (regional to cerebellar ratio) for all 5 patients was sig nificantly correlated with the corresponding regional CMRO2 values (r= .45, P<.05). However, no significant correlation was found of the IMZ uptake with either the regional CBF or the regional CMRGlc. Conclusion s The use of IMZ SPECT provides new information on the neuronal altera tion induced by chronic ischemic cerebrovascular disease.