Diagnosis and outcome of renal function in patients with renal artery stenosis: which role have color Doppler sonography and magnetic resonance angiography?

AIM: Minimally invasive diagnostic techniques would be useful in the preoperative diagnosis of patients with hypertension and ischemic renal disease. The aim of our study was to compare color Doppler sonography (CDS), and magnetic resonance angiography (MRA) with the reference standard, digital subtraction angiography (DSA), in the diagnosis of renal artery stenosis. METHODS: Thirty-nine patients with arterial hypertension and monolateral or bilateral renal artery stenosis documented by CDS underwent renal artery MRA and then DSA during corrective percutaneous transluminal angioplasty. CDS and MRA scans were evaluated by 3 independent observers who studied 78 main renal arteries. Stenosis of 70% or more were regarded as significant. Sensitivity, specificity, positive and negative predictive values and two-sided 95% confidence intervals of CDS and MRA for the detection of significant renal artery stenosis were calculated. The statistical significance of the differences in sensitivities between CDS and MRA was assessed by means of the kappa test (< or =1). RESULTS: CDS and MRA, therefore, both achieved 97.6% sensitivity and 100% specificity for diagnosing stenoses at the origin of the renal artery; CDS yielded 100% sensitivity and 97.1% specificity and MRA 87.5% sensitivity and 98.6% specificity for diagnosing stenosis in the intermediate distal segments. CONCLUSIONS: Statistically significant differences between CDS and MRA in the diagnosis of renal artery stenosis have not been observed. However, according to our experience, CDS is the preferred technique because it also provides useful information about the development of kidney disease before correction.

Suprarenal artery stenosis may be mistaken for renal artery stenosis in Doppler studies.

There are several limitations in using colour-flow-Doppler (CFD) to diagnose renal artery stenosis. This report describes a case of "false positive" stenosis of the renal artery diagnosed using CFD. A patient affected by arterial hypertension and with a suspected stenosis of the renal artery was examined using CFD. However, the patient was in fact suffering from suprarenal artery stenosis.