A comparative I-123 IMP SPECT study in Binswanger's disease and Alzheimer's disease.

The regional cerebral blood flow in 31 patients was semiquantitatively measured with SPECT using N-isopropyl iodo-amphetamine (I-123 IMP). Of the 31 patients, 9 had Binswanger's disease (BD) (mean age: 64.2 years), 10 had Alzheimer's disease (AD) (mean age: 66.8 years), and 12 were neurologically normal (mean age: 67.8 years). Tracer activity was determined in 7 pairs of cerebellar, cortical, and subcortical regions and was expressed as two ratios: the activity in each region of interest (ROI) compared to the mean count in the cerebellar region (ROI/CER ratio) and compared to the mean count in the occipital cortex (ROI/OCC ratio). Patients with BD showed a reduction of the ROI/CER ratio in the temporal cortex, thalamus, and basal ganglia compared to normal subjects. However, the ROI/CER ratio for the occipital region was higher than that of normal controls, suggesting that cerebellar blood flow was reduced in patients with BD. AD patients showed a decreased ROI/CER ratio in the frontal, temporal, and parietal cortices. Both BD and AD patients showed decreased ROI/OCC ratios in all the cortical and subcortical regions compared to the neurologically normal patients. In BD patients, the most marked reduction of both ratios was found in the thalamus, while for AD patients the most prominent reduction was seen in the parietal cortex. Our results indicate that these two types of dementia show characteristic regional cerebral blood flow patterns, which may be associated with their clinical features.