Single photon emission computed tomography using 99Tcm-HMPAO in Alzheimer's disease

Brain single photon emission computed tomography (SPET) using 99mTcm-hexamethylpropyleneamine oxime (HMPAO) was performed in 37 patients satisfying the standard clinical criteria of Alzheimer's disease (AD), correlating results with patient's age of onset, duration of illness, severity of dementia, neuropsychological impairment, computed tomography (CT) and EEG findings. All patients had abnormal SPET: 23 were bilaterally symmetric, 10 were bilaterally asymmetric and four showed unilateral low regional cerebral perfusion. Low perfusion in bilateral parietal regions was the most consistent finding and was present alone or with other abnormal regions in 31 patients (84%). The only significant clinical correlation was found between asymmetric SPET changes and onset of disease before the age of 65 years. Fifty per cent of patients with presenile onset, but only 19% with senile onset had asymmetric low regional cerebral perfusion. Fifteen of the 36 patients had normal brain CT scans, and 9 of 31 patients receiving EEG examination had normal results. Although clinical evaluation is the most valuable diagnostic tool, brain SPET is a sensitive test for physiological investigation in AD.