BENZODIAZEPINE RECEPTORS IN CHRONIC CEREBROVASCULAR-DISEASE - COMPARISON WITH BLOOD-FLOW AND METABOLISM

The brain benzodiazepine (BZD) receptor distribution in patients with chronic cerebrovascular disease was assessed with I-123-iomazenil (IMZ ) SPECT, and the findings were compared with the data for the cerebral blood flow (CBF) and cerebral metabolism. Methods: We examined nine p atients with chronic cerebrovascular diseases, six patients with cereb ral infarction and three with moyamoya disease. Iodine-123-IMZ SPECT i mages were obtained for 15 min, 3 hr after the administration of 167 o r 222 MBq I-123-IMZ. In seven patients, the CBF and oxygen metabolism were measured by the O-15 steady-state method. In two patients, the CB F and glucose metabolism were measured by Tc-99m-HMPAO SPECT and F-18- fluoro-2-deoxy-D-glucose-PET, respectively. The brain was initially cl assified into 18 regions, and abnormalities in the BZD receptor distri bution, CBF and cerebral metabolism were visually evaluated. The count ratio of lesion-to-contralateral normal region (L-to-C ratio) was the n used for comparison. Results: In the core of the infarct, the I-123- IMZ uptake decreased (L-to-C ratios of the blood flow 0.42 +/- 0.26; m etabolism 0.45 +/- 0.24; and I-123-IMZ uptake 0.46 +/- 0.14). In the p eri-infarct region, the I-123-IMZ uptake slightly decreased (L-to-C ra tios of 0.81, 0.82 and 0.89, respectively). In the region of misery pe rfusion, the I-123-IMZ uptake was preserved (L-to-C ratios of 0.73, 1. 07 and 1.02, respectively). In the remote deafferentated areas in the ipsilateral cerebrum, the I-123-IMZ uptake was preserved (L-to-C ratio s of 0.76 +/- 0.10, 0.75 +/- 0.04 and 0.98 +/- 0.05, respectively). In the remote areas in the contralateral cerebellum, the I-123-IMZ uptak e was preserved (L-to-C ratios of 0.84 +/- 0.08, 0.85 +/- 0.04 and 0.9 4 +/- 0.05, respectively). Conclusion: The BZD receptor distribution, as measured by I-123-IMZ SPECT, is not considered to reflect neuronal function, but it may reflect neuronal cell viability. Iodine-123-IMZ S PECT may, therefore, hold promise as a potential probe for neuronal da mage.