Diagnosis of Renal Artery Stenosis

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The summary below is from the full report titled "Accuracy of Computed Tomographic Angiography and Magnetic Resonance Angiography for Diagnosing Renal Artery Stenosis." It is in the 2 November 2004 issue of Annals of Internal Medicine (volume 141, pages 674-682). The authors are G.B.C. Vasbinder, P.J. Nelemans, A.G.H. Kessels, A.A. Kroon, J.H. Maki, T. Leiner, F.J.A. Beek, M.B.J.M. Korst, K. Flobbe, M.W. de Haan, W.H. van Zwam, C.T. Postma, M.G.M. Hunink, P.W. de Leeuw, and J.M.A. van Engelshoven, for the Renal Artery Diagnostic Imaging Study in Hypertension (RADISH) Study Group.

What is the problem and what is known about it so far?

Renal artery stenosis is a narrowing of the artery that supplies blood to the kidney. It can cause kidney dysfunction and high blood pressure. One of the most accurate ways to detect renal artery stenosis is to x-ray the renal arteries after injecting them directly with dye. This test, called intra-arterial digital subtraction angiography, or DSA, is invasive and sometimes dangerous. Thus, physicians often use alternative tests, such as computed tomographic angiography (CTA) and magnetic resonance angiography (MRA), to detect renal artery stenosis. These tests show pictures of arteries that have been injected with very small amounts of dye. Computed tomographic angiography uses x-ray beams and MRA uses radio waves and a magnetic field to take the pictures. Unfortunately, few studies address how well either of these tests detects renal artery stenosis.

Why did the researchers do this particular study?

To see if CTA and MRA are reliable, accurate tests for detecting renal artery stenosis.

Who was studied?

402 hypertensive adults with suspected renal artery stenosis from 6 hospitals in the Netherlands.

How was the study done?

The researchers recruited hypertensive patients who had at least 1 historical, physical, or laboratory finding that suggested the possibility of renal artery stenosis. Within a 3-month period, each patient had CTA, MRA, and DSA. Two panels of 3 trained physicians who had no knowledge of other test results interpreted the CTA and MRA images. The researchers then assessed whether the physicians' interpretations agreed and also compared the results of CTA and MRA with DSA results.

What did the researchers find?

The physicians sometimes disagreed about whether CTA and MRA showed renal artery stenosis. These tests detected only 64% and 62%, respectively, of the patients who had DSA findings of renal artery stenosis.

What were the limitations of the study?

The comparison standard test, DSA, is not a perfect test for diagnosing renal artery stenosis.

What are the implications of the study?

Even trained physicians may have difficulty interpreting CTA and MRA. In this study, neither CTA nor MRA was a sensitive test for detecting renal artery stenosis.