Renal arteriography using gadolinium enhanced 3D MR angiography--clinical experience with the technique, its limitations and pitfalls.

Gadolinium enhanced 3D MR angiography (MRA) is becoming a widely accepted technique for imaging the vascular system. We set out to evaluate its accuracy and reliability in visualization of renal arteries in the clinical setting. Gadolinium enhanced MRA was performed in 15 potential live renal donors and 26 patients suspected of having renal artery stenosis who were referred for digital subtraction angiography (DSA). MRA was performed on a 1.5 T MR scanner in a single breath hold. Images from each study were prospectively analysed for demonstration of number of main and accessory renal arteries and degree of renal artery stenosis in a double blind fashion. All the main and accessory arteries were visualized on MRA in the renal donor group, but in one case a branch was not identified owing to breathing artefact. In one case, an extrarenal vascular anomaly was not demonstrated on MRA. In the renal artery stenosis group, sensitivity, specificity and negative predictive values of 96%, 93% and 96% were obtained for clinically significant stenosis (>50%). Gadolinium enhanced MRA proved to be a useful technique in demonstration of renal arterial anatomy and grading of renal artery stenosis. However, we encountered some pitfalls and limitations of the technique during the process. It is important to be aware of these before accepting it as the sole technique in clinical practice.