FUNCTIONAL MAPPING OF HUMAN SENSORIMOTOR CORTEX WITH 3D BOLD FMRI CORRELATES HIGHLY WITH (H2O)-O-15 PET RCBF

Positron emission tomography (PET) functional imaging is based on chan ges in regional cerebral blood flow (rCBF). Functional magnetic resona nce imaging (fMRI) is based on a variety of physiological parameters a s well as rCBF. This study is aimed at the cross validation of three-d imensional (3D) fMRI, which is sensitive to changes in blood oxygenati on, with oxygen-15-labeled water ((H2O)-O-15) PET. Nine normal subject s repeatedly performed a simple finger opposition task during fMRI sca ns and during PET scans. Within-subject statistical analysis revealed significant (''activated'') signal changes (p < 0.05, Bonferroni corre cted for number of voxels) in contralateral primary sensorimotor- cort ex (PSM) in all subjects with fMRI and with PET. With both methods, 78 % of all activated voxels were located in the PSM. Overlap of activate d regions occurred in all subjects (mean 43%, SD 26%). The size of the activated regions in PSM with both methods was highly correlated (rho = 0.87, p < 0.01). The mean distance between centers of mass of the a ctivated regions in the PSM for fMRI versus PET was 6.7 mm (SD 3.0 mm) . Average magnitude of signal change in activated voxels in this regio n, expressed as z-values adapted to timeseries, z(t), was similar (fMR I 5.5, PET 5.3). Results indicate that positive blood oxygen level-dep endent (BOLD) signal changes obtained with 3D principles of echo shift ing with a train of observations (PRESTO) fMRI are correlated with rCB F, and that sensitivity of fMRI can equal that of (H2SO)-S-15 PET.