Corticobasal degeneration and Parkinson's disease assessed by HmPaO SPECT: the utility of factorial discriminant analysis.

The diagnosis of corticobasal degeneration (CBD) is difficult despite the existence of some typical clinical features. Single photon emission computerized tomography (SPECT) in CBD presents an original pattern (with asymmetric hypoperfusion in pre- and retrorolandic regions) that could facilitate the differential diagnosis of CBD relative to the other degenerative parkinsonian syndromes. The objective of our study was to compare the regional cerebral blood flow measurements studied by SPECT in both CBD and Parkinson's disease (PD) using a multivariate procedure. Twenty-one patients with probable CBD and 20 patients with probable PD underwent brain (99m)Tc HmPaO SPECT. We used factorial discriminant analysis (FDA) to study the relative fixation of 26 regions of interest (ROIs) drawn on two transverse slices, together with the asymmetry indexes of 13 pairs of ROIs. FDA performed using the full set of parameters classified all the patients correctly. In order to classify the patients more easily, a predictive score using a selection of parameters was established. The most discriminating ROIs were the temporoinsular, temporoparietal, and frontal medial regions. We believe that this semiautomatic classification may be a precious tool for reinforcing the current clinical differential diagnosis of CBD and PD.