Unenhanced MR angiography of renal arteries: 51 patients

The purpose of this research was to assess the feasibility and performance of an unenhanced 3D balanced steady-state free precession (SSFP) sequence, compared with contrast-enhanced MR angiography (CEMRA), which is the reference standard to detect and quantify renal artery stenoses (RAS).

Fifty-one patients were included in this prospective study. Balanced SSFP sequence (Native) and CEMRA were performed using a 1.5-T magnet. Signal quality and stenosis grade were assessed per segment for renal arteries and for ostia of celiac trunk and superior mesenteric artery (SMA). We compared signal quality of Native and CEMRA. Sensitivity, specificity, negative predictive value (NPV), and accuracy were also calculated.

Evaluation involved 114 renal arteries, 51 celiac trunks, and 51 SMAs. By use of CEMRA, 20 significant stenoses were found for renal arteries, 10 stenoses and three occlusions for celiac trunk, and three stenoses for SMA. At artery-by-artery analysis, sensitivity, specificity, accuracy, and NPV of the balanced SSFP sequence in detecting stenosis were respectively 85%, 96%, 94%, and 96% for renal arteries; 100%, 97%, 98%, and 100% for celiac trunk; and 100%, 100%, 100%, and 100% for SMA. No significant difference of signal quality was found for the entire examination and for the different segments evaluated except for hilar and intrarenal branches, which showed better signal quality on balanced SSFP sequence.

The NPV results in our study suggest that unenhanced balanced SSFP MR angiography can be the first-choice imaging method to exclude RAS in patients at high risk of nephrogenic systemic fibrosis. However, when stenosis is found, other imaging modalities are necessary for better estimation.