FMRI and PET of self-paced finger movement: Comparison of intersubject stereotaxic averaged data

We compared the intersubject-averaged functional anatomy of self-paced righ t index finger movement as revealed by O-15 water positron emission tomogra phy (PET) and blood oxygen level-dependent functional magnetic resonance im aging (FMRI) at 1.5 T. Image data sets were acquired with both techniques o n a group of eight subjects, spatially normalized in the stereotaxic space and subsequently processed in order to get identical smoothness and degrees of freedom. Intersubject-averaged PET and FMRI activation maps were found congruent in the left primary sensorimotor area (PSM), bilateral supplement ary motor area, bilateral supra marginalis gyri, left operculum, left infer ior parietal lobule, right middle frontal gyrus, and right cerebellum. In t hose regions the mean distance between PET and FMRI local maxima was 7.4 mm . FMRI detected additional activations in the right precentral gyrus, right rolandic operculum, right inferior parietal lobule, and bilateral insula, whereas PET demonstrated a higher detection sensitivity at the deep nuclei level. PET and FMRI percentage signal Variations were found linearly relate d by a factor around 10, both within the PSM and across a set of distribute d local extrema. However, in most cases, FMRI was more sensitive than PET, as assessed by t values. Finally the pattern of deactivations was markedly dissimilar between the two techniques, possibly due to differences in the " Rest" control task. (C) 1999 Academic Press.