Magnetic resonance angiography of renal artery stenosis.

Magnetic resonance angiography is a new noninvasive technique capable of imaging the renal arteries without nephrotoxic contrast agents. Therefore, it may play an important role in patients with suspected ischemic nephropathy. The objective of this discussion is to review the current state of the art of renal magnetic resonance angiography, including a description of the methods for performing magnetic resonance angiography, applications of the techniques specifically to the renal arteries, and a review of the results of several validation studies. These validation studies have reported sensitivities ranging from 83% to 100% and specificities from 92% to 97% for detecting significant (> 50%) renal artery stenoses. In addition, magnetic resonance techniques capable of evaluating renal function, including direct measurement of renal blood flow and glomerular filtration rate in individual kidneys, are described.