Theoretical and experimental evaluation of phase-dispersion effects caused by brain motion in diffusion and perfusion MR imaging

摘要: We investigated intravoxel phase dispersion caused by pulsatile brain motion in diffusion spin-echo pulse sequences. Mathematical models were used to describe the spatial and temporal velocity distributions of human motion. The distribution brain-tissue introduces a spread over one voxel, leading signal loss. This loss was estimated theoretically, effects on observed coefficient perfused capillary fraction assessed. When parameters from sequence without compensation used, ECG triggering with inappropriate delay times assumed, maximal brain-motion-induced predicted be 21%. corresponds 95% overestimation coefficient, perfusion-fraction error small. Corresponding calculations for motion-compensated sequences 1% 1.5% due undesired dispersion, whereas experimental results indicated related 4%.