Magnetic resonance renal angiography and venography: an analysis of 111 consecutive scans before donor nephrectomy.

Objective: To determine the accuracy of magnetic resonance imaging (MRI) renal angiography in predicting vascular anatomy before donor nephrectomy, to determine the significance of missed vessels and to ascertain whether vessels are missed because of technical limitations or errors in interpretation.

Patients And Methods: In all, 111 consecutive living donations were assessed; the anatomy on MRI before donation was compared with that at nephrectomy. The significance of additional arteries and veins was recorded at the time of donation, with extra vessels either anastomosed or sacrificed. Finally, the scans in which extra vessels had not been identified were re-examined to establish whether these could be identified retrospectively.

Results: In all, 93 kidneys had a single renal artery and 18 had two. All lower pole arteries were anastomosed and all upper pole arteries were sacrificed. Nine arteries were identified before surgery (five were to the lower pole), and nine were missed (four to the lower pole). There were 13 kidneys with more than one vein. Four of these were seen on MRI. However, an extra vein was anastomosed in only one case. On review of the imaging, three arteries were missed because of human error and six due to technical limitations. Of the nine missed veins, only three were easily identified retrospectively. Overall, using MRI as a preoperative investigation for the 111 consecutive cases, the surgeon encountered a previously unidentified accessory artery in nine (8%), and this required anastomosis in four (4%).

Conclusion: MR angiography has the advantage over computed tomography (CT) of having virtually no side-effects, and if the small possibility is accepted of missing extra vessels because of technical limitation or interpretation, it is a good investigation. However, in light of the failure to visualize all arteries transplanted, we have started to use multi-slice (16-channel) CT to see if its improved spatial resolution alters the results.