SUPPRESSION OF VASCULAR ARTIFACTS IN FUNCTIONAL MAGNETIC-RESONANCE IMAGES USING MR ANGIOGRAMS

This paper describes a method for processing functional magnetic reson ance images that suppresses signal changes originating from macroscopi c reins visible in acquired magnetic resonance angiograms. Finger tapp ing experiments were performed on a 1.5-T scanner and the response was evaluated with voxel-by-voxel cross-correlation of the time course wi th a sinusoid at the paradigm frequency. After applying a vascular mas h to suppress signal changes under macroscopic vessels, the vascular a nd non vascular subpopulations of the data were compared. By visual in spection, the method was found to remove extracortical activation whil e preserving activation in the parenchyma. The observed higher signal amplitudes and temporal phase lags of the vascular population agree wi th theoretical models and previous studies. A significant portion of n egatively correlated voxels occurs adjacent to through-plane vessels. Finally, comparing the centers of mass of the activated area before an d after vascular suppression showed significant shifts in some subject s. (C) 1998 Academic Press.