Non-contrast-enhanced magnetic resonance angiography: a reliable clinical tool for evaluating transplant renal artery stenosis.

PURPOSE: To evaluate image quality of non-contrast-enhanced magnetic resonance angiography (MRA) and compare transplant renal artery stenosis (TRAS) seen by non-contrast-enhanced MRA with digital subtraction angiography (DSA) as the gold standard.

MATERIALS AND METHODS: 330 patients receiving 369 non-contrast-enhanced MRA examinations from July 2014 to June 2017 were included. Thirty patients received at least two MRA examinations. Image quality was independently assessed by two radiologists. Inter-observer agreement was analyzed. Transplant renal artery anatomy and complications were evaluated and compared with DSA. If possible, accuracy was calculated on a per-artery basis.

RESULTS: Good or excellent image quality was found in 95.4 % (352/369) of examinations with good inter-observer agreement (K=0.760). Twenty-two patients with DSA had 28 non-contrast-enhanced MRA examinations within a 2-month period. Of these, 19 patients had TRAS, two patients had pseudoaneurysms, and one patient had a normal transplant renal artery but an occluded external iliac artery. Non-contrast-enhanced MRA correctly detected 19 TRAS and nine normal arteries, giving 96.6 % accuracy on a per-artery basis.

CONCLUSIONS: Non-contrast-enhanced MRA demonstrates a good depiction of the transplanted renal artery and shows good correlation with DSA in cases where there was TRAS.

KEY POINTS: • Good or excellent image quality was found in 95.4 % of examinations. • Non-contrast-enhanced MRA can clearly map transplant renal artery anatomy. • Non-contrast-enhanced MRA is a reliable tool to detect TRAS.