THE DISCRIMINANT VALUE OF SEMIQUANTITATIVE SPECT DATA IN MILD ALZHEIMERS-DISEASE

In most semiquantitative SPECT studies, overlap between groups of pati ents with Alzheimer's disease (AD) and age-matched elderly controls is such that single posterior cortical perfusion measurements lack sensi tivity. In the present study, the value of a combination of semiquanti tative temporoparietal SPECT parameters was examined. Methods: Suprate ntorial transaxial perfusion measurements were obtained in frontal, an terior temporal, posterior temporoparietal and occipital cortical area s in both hemispheres, in a baseline population of 10 healthy elderly controls and 30 mild to moderately impaired AD patients, as well as in a prospective group of 15 patients with mild cognitive impairment, 12 patients with a diagnosis of probable AD and individual cases of mult i-infarct dementia, dementia-frontal type and paranoid psychosis. A li near discriminant function (LDF) was calculated from the baseline subj ects' data to classify control and AD subjects individually. Results: Highly significant hypoperfusion was noted in both the anterior tempor al and posterior temporoparietal regions of interest in the AD group c ompared with controls, but with significant overlap. Using an LDF inco rporating these perfusion measurements in both hemispheres, 10/10 (100 %) controls and 26/30 (87%) AD baseline subjects were correctly classi fied. Using the baseline LDF in the prospective 15 mildly impaired cas es, 11/12 new mild AD cases and none of the 3 non-AD cases were classi fied in the AD group. Conclusion: These results support the use of a c ombination of semiquantitative SPECT perfusion estimates from cortical areas with predictable pathological involvement in AD in a linear dis criminant format in the clinical assessment of patients with suspected AD.