Role of contrast agent perfusion and of diffusion in the NMR signal enhancement of liver lesions.

Both perfusion and diffusion contribute to NMR signal enhancement after intravenous injection of a nonspecific contrast agent. In the present study the roles of perfusion and diffusion in the contrast enhancement of induced liver lesions in the rat and the rabbit were evaluated. This was done by comparing Gd-DOTA absolute enhancement signal-to-noise versus time plots of various lesions with the findings from microangiography and histology. Four types of enhancement could be recognized. Diffusion was the major factor in the delayed enhancement seen in lesions that had large extravascular diffusion space.