MR imaging of renal function.

MR imaging has advantages over both computed tomography and nuclear scintigraphy for assessing renal function, because it combines high spatial resolution with information on perfusion and function. A further advantage is the lack of ionizing radiation. Quantitation of flow rate by phase contrast in the renal arteries and veins has the potential to provide estimation of renal blood flow, which could prove useful in a number of clinical situations, especially for studying renal vascular disorders and the effects of treatment, and for assessing renal transplants. Evaluation of renal perfusion with MR imaging has become feasible with the development of rapid data acquisition techniques, which provide adequate temporal resolution to monitor the rapid signal changes during the first passage of the contrast agents in the kidneys. More recently, magnetically labeling water protons in blood flowing into kidneys has been used to noninvasively quantitate regional measurement of cortical and medullary perfusion. Other techniques being investigated with MR imaging for assessment of renal function include diffusion imaging GFR estimation and blood oxygenation level dependent imaging to evaluate intrarenal oxygenation levels.