Aim: The diagnostic work-up of renal transplants with impaired function due to urological problems can be difficult. This study was performed to assess sensitivity and specificity of non-invasive contrast-enhanced MR urography (MRU).
Methods and materials: Thirty-five patients with renal transplants (25 - 71 years, mean: 53.4 years) with sonographically diagnosed hydronephrosis or perirenal fluid collections were assessed by MR urography. MR examinations were carried out at a 1.5 T clinical scanner (Vision, Siemens, Erlangen, Germany) with a 512 matrix contrast-enhanced fat-suppressed T1-weighted FLASH 3D sequence in breath-hold technique. MIP reconstructions were used to produce MR urography. MRU diagnoses were compared to operative results.
Results: In all patients, images with sufficient contrast in the renal collecting system were obtained. Hydronephrosis was confirmed in 20 patients, 8 patients showed a different pathology while 7 had normal findings. Compared to operative results, sensitivity of MRU was 100% with a specificity of 78%, respectively. One ureteral stone was misdiagnosed as a stricture, and 2 suspected ureteral stenoses could not be found upon operation.
Conclusions: Contrast-enhanced MR urography is a highly sensitive and specific non-invasive method to evaluate patients suspected of having typical post-transplant urological complications. It may replace invasive procedures such as antegrade pyelography in the pre-operative work-up.