Central Benzodiazepine Receptor Distribution After Subcortical Hemorrhage Evaluated by Means of [ 123 I]Iomazenil and SPECT

Abstract

Background and Purpose [ 123 I]Iomazenil is a single-photon emission computed tomography (SPECT) tracer that selectively binds to central benzodiazepine receptor in the neuron membrane. With this ligand, we studied the central benzodiazepine receptor distribution in the cortex remote from subcortical hematoma in intracerebral hemorrhage patients. Methods Four patients with unilateral putaminal hemorrhage and one patient with right thalamic hemorrhage were studied (mean±1 SD age, 50.0±8.8 years). The initial volume of hematoma ranged from 4.3 to 31.0 mL (mean±1 SD, 17.5±12.3 mL). SPECT images obtained 3 hours after intravenous administration of [ 123 I]iomazenil (167 MBq/750 ng) were analyzed. In three patients, perfusion was evaluated with [ 123 I]IMP. On SPECT images, the radioactivity ratio of the ipsilateral to the contralateral cerebral cortex (I/C ratio) or of the contralateral to the ipsilateral cerebellar hemisphere (C/I ratio) was measured. Results The I/C ratio for iomazenil was significantly decreased compared with unity in the temporal lobe (0.84±0.08, P <.01) and the parietal lobe (0.87±0.10, P <.05), but the C/I ratio in the cerebellum (1.00±0.03) was not. The C/I ratio for perfusion in the cerebellar cortex (0.83±0.04, P <.01) was significantly decreased compared with that in normal subjects. Conclusions Central benzodiazepine receptor–[ 123 I]iomazenil binding was decreased in the ipsilateral cerebral cortex remote from the subcortical hematoma. This preliminary result may facilitate further study of the potential damage of the cortical neurons remote from subcortical hematoma.