Renal artery stenosis: imaging options, pitfalls, and concerns.

Renal artery stenosis can be diagnosed with multiple imaging modalities, each one having different risk vs accuracy tradeoffs. Catheter angiography with pressure gradient measurements is the definitive gold standard but also the most invasive and thus reserved primarily for imaging at the time of renal revascularization. Ultrasonography is the safest and least expensive but also the least accurate and most operator-dependent. Contrast-enhanced computed tomographic angiography and magnetic resonance angiography are intermediate (between ultrasound and catheter angiography) with respect to accuracy and expense. Exciting new advances in magnetic resonance that include new contrast agents, which eliminate nephrogenic systemic fibrosis risk, and techniques to characterize the hemodynamic significance of renal artery stenoses are now becoming available. In addition, magnetic resonance angiography without any contrast has become more accurate and rivals contrast-enhanced techniques in some patients. This review explores these techniques for renal artery stenosis imaging.