Semi-quantitative analysis of perfusion of Brodmann areas in the differential diagnosis of cognitive impairment in Alzheimer's disease, fronto-temporal dementia and mild cognitive impairment

Abstract

Different perfusion defects reflect neurological damage characteristics of different kinds of dementia. Our aim was to investigate the role of brain single photon emission tomography (SPET) with semiquantitative analysis of Brodmann areas in dementia, by technetium-99m - hexamethyl-propylenamine- oxime ((99m)Tc-HMPAO) brain SPET with semiquantitative analysis of Brodmann areas in patients with Alzheimer's disease (AD), frontotemporal dementia (FTD) and mild cognitive impairment (MCI). We studied 75 patients, 25 with AD (NiNCDS ADRDA criteria), 25 with FTD (Lund and Manchester criteria), 25 with MCI (EADC criteria). After i.v. injection of 740MBq of (99m)Tc-HMPAO, each patient underwent brain SPET. A software application was used able to map the SPET brain image to a stereotaxic atlas (Talairach), providing an affine co-registration by blocks of data defined in the Talairach space. A normal database calculating voxel by voxel the mean and the standard deviation of the measured values was built. Functional SPET data of 3D regions of interest (ROI) of predefined Brodmann's area templates were compared with those of a database of healthy subjects of the same age and gender. Mean values obtained in the Brodmann area ROI in the different groups of patients studied were evaluated. Our results showed that different Brodmann areas were significantly impaired in the different categories of dementia subjects. Both areas 37 (temporal gyrus) and 39 (angular gyrus) of AD patients (mean+/-SD: 37L= -1.6+/-1.0; 37R= -1.5+/-1.1; 39L= -2.3+/-1.3; 39R= -1.9+/-1.2) showed significant hypoperfusion (P<0.05) versus MCI (37L= -0.9 +/-0.7; 37R= -1.1+/-0.9; 39L= -1.4+/-1.1; 39R= -1.6+/-1.6.) and FTD (37L= -1.1+/-0.8; 37R= -1.0+/-0.9; 39L= -1.4+/-1.0; 39R= -1.2+/-1.2) subjects. AD patients showed significantly (P<0.01) decreased perfusion in areas 40 (supramarginal gyrus) (40L= -2.6+/-1.0; 40R= -2.3+/-1.1) with respect to MCI patients (40L= -1.8+/-0.9; 40R= -1.7+/-1.2). Finally, FTD patients showed significant hypoperfusion (P<0.05) in both areas 47 (frontal association cortex) (47L= -1.8+/-0.8; 47R= -1.1+/-0.8) in comparison with MCI subjects (47L= -1.2+/-0.9; 47R= -0.9+/-0.9). In conclusion, our results suggest that semiquantitative analysis of single Brodmann areas identify frontal area hypoperfusion in FTD patients and also parietal and temporal impairment in AD patients. In MCI patients, no hypoperfusion pattern is identified.