Steady‐state free precession MRA of the renal arteries: Breath‐hold and navigator‐gated techniques vs. CE‐MRA

Abstract

To explore the use of breath-hold and navigator-gated noncontrast Steady State Free Precession (SSFP) MR angiography (MRA) protocols for the evaluation of renal artery stenosis (RAS). Twenty patients referred to rule out RAS were imaged using two breath-hold and one navigator-gated SSFP MRA sequences. All patients underwent contrast-enhanced MRA (CE-MRA). Two radiologists evaluated all sequences both qualitatively (blur, artifacts, reader confidence) and quantitatively (maximum stenosis). Using CE-MRA as truth, a receiver operating characteristics (ROC) curve was generated and a statistical analysis of navigator-gated SSFP (Nav SSFP) was performed. Seven patients had >50% renal artery stenosis by CE-MRA. Nav SSFP performed significantly better than either breath-hold SSFP technique in terms of blur, artifacts, and reader confidence. Using a 50% threshold for stenosis, sensitivity for detecting RAS was 100%, with a specificity of 85% and a negative predictive value of 100%. The average mean stenosis difference between Nav SSFP and CE-MRA was 9 +/- 9%. Nav SSFP outperformed breath-hold SSFP in measures of image quality and reader confidence. Sensitivity and negative predictive value for detecting RAS with Nav SSFP was perfect, with an acceptable specificity of 85%. This suggests further study is warranted to evaluate Nav SSFP as a noncontrast screening technique for renal artery stenosis.