Assessment of renal artery stenosis: Comparison of captopril renography and gadolinium-enhanced breath-hold MR angiography

AIM: To determine the accuracy of captopril renography (CR) and gadolinium-enhanced breathhold magnetic resonance (MR) angiography in the diagnosis of 50-99% renal artery stenosis (RAS), MATERIALS AND METHODS: Forty-three patients with possible RAS, of whom 53% had renal function impairment (creatinine >130 mu mol/l), were included, Tc-99m-mercaptoacetyl triglycine (MAG(3)) renography was performed after an oral dose of 25 mg captopril, Gadollnium-enhanced MR angiography was performed on a standard 1.5 Tesla system: TR 13.5, TE 3.5, flip angle 60 degrees, matrix 195 x 512. Intra-arterial digital subtraction angiography (DSA) was the standard of reference. RESULTS: Captropril renography accurately categorized 22 of 26 patients who had either uni- or bilateral RAS of 50-99%, The sensitivity and specificity of CR for the detection of 50-99% stenosis were 85 and 71%, respectively. With MR angiography one occluded artery was incorrectly diagnosed as a stenosis, Sensitivity and specificity were 100 and 94%, respectively. The difference between the accuracies of MR angiography and CR was statistically significant (P = 0.02). The accuracy of CR was lower in patients with renal impairment (70%) than in those with normal renal function (90%). CONCLUSION: MR angiography showed a high accuracy in diagnosing RAS of between 50 and 99%, CR was less accurate than MR angiography, especially in patients with renal function impairment, In patients with normal renal function, however, CR remains a useful diagnostic test, Bongers, V. et al. (2000). Clinical Radiology 55, 346-352 (C) 2000 The Royal College of Radiologists.