Williams GJ et al. (2007) Comparative accuracy of renal duplex sonographic parameters in the diagnosis of renal artery stenosis: paired and unpaired analysis. AJR Am J Roentgenol 188: 798–811

The current reference standard for the diagnosis of renal artery stenosis (RAS) is intra-arterial angiography. No single screening method that identifies patients who require this invasive procedure has been universally accepted. Williams and co-workers, therefore, performed a meta-analysis of studies that compared the accuracy of duplex sonography with that of intra-arterial angiography for the detection of RAS.

The authors selected 88 original articles published in the period 1984–2004, and extracted data on 9,974 renal arteries in 8,147 patients. A range of parameters obtained via duplex sonography were assessed for diagnostic capabilities; these parameters included peak systolic velocity (PSV), acceleration time, acceleration index, and renal–aortic ratio.

PSV was the most accurate test parameter with a sensitivity of 85%, specificity of 92% and a diagnostic odds ratio (OR) of 60.9. The acceleration index was the least accurate test parameter with an OR of 16.0. Acceleration time and renal–aortic ratio had similar diagnostic ORs of 28.9 and 29.3, respectively. Combining PSV with other duplex sonography parameters increased diagnostic accuracy only marginally.

The authors conclude that determining PSV alone using duplex sonography is a useful, inexpensive and noninvasive means of triaging patients in whom RAS is suspected, allowing unnecessary renal angiography to be avoided.