Hemodynamic effect of iodinated high-viscosity contrast medium in the rat kidney - A diffusion-weighted MRI feasibility study

RATIONALE AND OBJECTIVES. TO assess the abilities of dynamic diffusion-weig hted MRI to demonstrate the effects in vivo of a high-viscosity iodinated c ontrast agent on medullary and cortical blood flow in the rat kidney, METHODS. Dynamic diffusion-weighted, echoplanar MR images obtained from fiv e b-value single-shot acquisitions and their isotropic apparent diffusion c oefficient maps were obtained from nine rats anesthetized by pentobarbital sedation, before and after intravenous injection of a high-viscosity, dimer ic iso-osmolar iodinated contrast medium (iodixanol), and compared with tho se obtained from four control rats that received saline. RESULTS. The mean baseline apparent diffusion coefficient values were 1.64 +/- 0.05 x 10(-3) mm(2)/s for the cortex and 1.75 +/- 0.06 x 10(-3) mm(2)/s for the medulla, In the iodixanol group, a significant decrease in renal d iffusion was observed at 12 minutes and lasted at least until 24 minutes. T he decrease in diffusion occurred earlier for the cortex and lasted less th an for the medulla, There was no significant modification in diffusion over time in the control group. CONCLUSIONS. This preliminary experience in rats shows that dynamic diffusi on-weighted MRI can be used to study noninvasively the in vivo renal hemody namic response after injection of iodinated contrast.