HEAD MOTION DURING POSITRON EMISSION TOMOGRAPHY - IS IT SIGNIFICANT

High sensitivity for detecting local brain function differences from s ubsequent PET-images acquired at different cerebral stimulation states requires interscan head motion to be minimized. This motion was measu red by an optical lever system during scanning (130 min) of 15 subject s in a dual-dose injection study. Despite motion restriction by a face -mask restraint system, rotations in the sagittal and coronal planes ( up to 4.1 degrees and 2.4 degrees, respectively) significantly influen ced the measured means and variances of local metabolic differences be tween states. Hence, adjustments for head movement by retrospective, d igital slice realignment or, better, real-time corrections are importa nt.