Navigator-gated MR angiography of the renal arteries: A potential screening tool for renal artery stenosis

OBJECTIVE. The purpose of our study was to determine how well unenhanced navigator-gated steady-state free precession ( Nav SSFP) MR angiography ( MRA) performs as a screening test for the detection of renal artery stenosis. SUBJECTS AND METHODS. Forty patients referred to rule out renal artery stenosis were imaged using an optimized Nav SSFP MRA sequence before conventional contrast-enhanced MRA ( CE-MRA). Two radiologists evaluated Nav SSFP for maximum stenosis measurement, and comparison was made with CE-MRA results. RESULTS. Fifteen of the 40 patients had greater than 50% renal artery stenosis as determined on CE-MRA. Sensitivity for detecting renal artery stenosis with Nav SSFP was 100%; specificity, 84%; negative predictive value, 100%; and positive predictive value, 79%. The average mean stenosis difference between Nav SSFP and CE-MRA was 10% +/- 9%. CONCLUSION. Sensitivity and negative predictive value for the detection of renal artery stenosis using Nav SSFP were perfect, with an acceptable specificity of 84%. This suggests Nav SSFP is a promising technique for simple unenhanced screening for the detection of renal artery stenosis.