BRAIN BLOOD-FLOW IN THE DEMENTIAS - SPECT WITH HISTOPATHOLOGIC CORRELATION IN 54 PATIENTS

PURPOSE: To evaluate single photon emission computed tomographic (SPEC T) imaging of regional cerebral blood flow in the diagnosis of Alzheim er disease (AD) and the differential diagnosis of the dementias. MATER IALS AND METHODS: Regional cerebral blood flow SPECT was performed wit h inhaled xenon-133 in 261 patients and with injected technetium-99m h examethyl-propyleneamine oxime (HMPAO) in 162 patients with possible d ementia. In 16 patients, both agents were used in 1 day. SPECT images obtained in elderly healthy control subjects (with Xe-133 in 15, with Tc-99m HMPAO in 14) were available. In each patient without AD, furthe r classification of disease was attempted. Histopathologic correlation was available in 54 patients (with autopsy in 51, with biopsy in thre e). RESULTS: SPECT diagnoses were true-positive in 37, true-negative i n eight, false-positive in three, and false-negative in six patients. Sensitivity was 86% (37 of 43; 95% confidence limits = .72, .95); spec ificity, 73% (eight of 11; confidence limits = .39, .94); positive pre dictive value, 92% (37 of 40; confidence limits = .80, .98); and negat ive predictive value, 57% (eight of 14; confidence limits = .29, .82). CONCLUSION: Regional cerebral blood flow SPECT may assist in the earl y and late diagnoses of AD and in the differential diagnosis of the de mentias when there is a complicated or confusing clinical picture.