An In Vivo Verification of the Intravoxel Incoherent Motion Effect in Diffusion-Weighted Imaging of the Abdomen

To investigate the vascular contribution to the measured apparent diffusion coefficient and to validate the Infra Voxel Incoherent Motion theory, the signal as a function of the b-value was measured in the healthy pancreas with and without suppression of the vascular component and under varying echo times (TE = 50, 70, and 100 msec). The perfusion fraction f and the diffusion coefficient D were extracted from the measured DW-data using the original Infra Voxel Incoherent Motion-equation and a modified version of this equation incorporating relaxation effects. First, the perfusion fraction f in the blood suppressed pancreatic tissue decreased significantly (P = 0.03), whereas the diffusion coefficient D did not change with suppression (P = 0.43). Second, the perfusion fraction f increased significantly with increasing echo time (P = 0.0025), whereas the relaxation time compensated perfusion fraction f' showed no significant dependence on TE (P = 0.31). These results verify a vascular contribution to the diffusion weighted imaging measurement at low b values and support the Intra Voxel Incoherent Motiontheory. Magn Reson Med 64:1580-1585, 2010. (C) 2010 Wiley-Liss, Inc.