[123I-IMP SPECT study on patients with amnestic syndrome].

Regional cerebral blood flow was studied using single photon emission CT (SPECT) with 123I-IMP to elucidate the pathophysiology of amnesia. Four patients with amnestic syndrome diagnosed by DSM-III-R criteria were investigated. SPECT images demonstrated definite hypoperfusion of the temporoparietal lobe and relative sparing of motor-sensory and occipital cortices in two out of four patients. Since these abnormalities of regional cerebral blood flow have been considered to be characteristic findings in dementia of the Alzheimer type, two patients with temporoparietal hypoperfusion are suggested to manifest the early stage of dementia of the Alzheimer type. Our observations suggest that 123I-IMP SPECT is an useful modality in the diagnosis of the early stage of dementia of the Alzheimer type, especially in patients with only memory impairment.