Correlation between <sup>99m</sup>Tc - HMPAO Brain Uptake and Severity of Dementia in Alzheimer's Disease: Assessment Using an Automatized Technique

Abstract

The aim of this study was to evaluate the correlations between the degree of dementia and the regional brain distribution of <sup>99m</sup>Tc-HMPAO in Alzheimer patients. Mini Mental Status Examination (MMSE) was used for deterioration evaluation. Regional cortical HMPAO uptake was analyzed by single photon emission tomography and an automatic technique for determination of lobe boundaries. Five regions were analyzed for each hemisphere: frontal, parietal, temporal, occipital and temporoparietal (TP). 39 patients satisfying the NINCDS-ADRDA criteria for probable Alzheimer''s disease (AD) and 10 controls of comparable age were included. There is a significant correlation between MMSE and the HMPAO uptake of the right temporal region of interest (p < 0.001) and right TP (p < 0,01) and left TP (p < 0.05). However, the regression curve is nonlinear, showing a strong correlation for severe cases (MMSE < 15) and a weak correlation for moderate cases. Within the subgroup of severe AD (n = 21; mean MMSE = 8.5) linear correlations are observed for parietal and occipital (p < 0.05), temporal and TP (p < 0.01) ROIs, but only on the right side. There is no significant correlation among the moderate AD subgroup (n = 18; mean MMSE = 20). We conclude that the HMPAO uptake of temporal and TP regions of the right hemisphere is correlated to the degree of dementia among severely demented patients.