Viable tissue in an area of severely reduced perfusion demonstrated with I-123 lomazenil brain SPECT imaging of benzodiazepine receptors

A 70-year-old woman who experienced transient left hemiparesis had 90% sten osis of the right internal carotid artery. CT revealed small low-density ar eas in the subcortical frontal area. Baseline cerebral blood flow was reduc ed, and vasoreactivity was poor in the right frontoparietal area according to I-123 IMP brain SPECT with acetazolamide. The distribution of I-123 ioma zenil was normal on the delayed SPECT image but reduced in the early SPECT image, mimicking baseline cerebral blood flow. The distribution of I-123 io mazenil SPECT on the delayed image reflected the normal binding potential o f the benzodiazepine receptor and thus identified viable tissue in an area of severely reduced perfusion. These findings were confirmed by positron em ission tomography.