What is the efficacy of magnetic resonance angiography (MRA) in the workup of renal artery stenosis (RAS)?

Updated: Nov 02, 2020
  • Author: Bruce S Spinowitz, MD, FACP; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

MRA has been validated only for the stenosis situated in the proximal 3-3.5 cm of renal arteries. Distal renal artery stenosis and segmental renal artery stenosis were generally not analyzed. The sensitivity of MRA was 90% for proximal renal artery stenosis, 82% for main renal artery stenosis, and 0% for segmental stenosis. In a follow-up study, Loubeyre and colleagues examined 46 patients with clinical renal artery stenosis. [21] Using a combination of techniques, they determined a sensitivity of 100%, a specificity of 90%, a positive predictive value of 58%, and a negative predictive value of 100% for detecting stenosis of the main, but not accessory or distal, renal artery. These data were obtained with fast-scanning machines using gadolinium enhancement and a breath-holding technique. [22]

An additional study compared the accuracy of CT angiography and MRA to digital subtraction angiography and concluded that digital subtraction angiography remains the method of choice to establish a diagnosis.

However, in the above-mentioned study by Garovic et al, the diagnostic efficacy of contrast-enhanced MRA (using 0.1 mmol/kg gadodiamide) was compared with that of intra-arterial digital subtraction angiography, using a cohort of 335 patients with known or suspected renal artery stenosis. The authors concluded, based on image analyses by multiple readers, that the sensitivity and specificity of the 2 modalities were equivalent in the evaluation of renal artery stenosis. [20]


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