Imaging in ureteral complications of renal transplantation: value of static fluid MR urography

Abstract

Ureteral obstruction is an infrequent complication after renal transplantation that may cause rapid loss of transplant function. We tested static fluid MR urography for determining the cause of graft hydronephrosis. Magnetic resonance urography was performed in nine transplants with dilated collecting systems on ultrasound. A heavily T2-weighted 3D turbo spin-echo sequence on a 1.5-T scanner was used and maximum intensity projections were obtained. The patients also underwent excretory urography (n = 1), renal scintigraphy (n = 1), antegrade pyelography (n = 3), voiding cystourethrography (n = 4), and non-enhanced CT (n = 2). Six patients had pathologic conditions including ureteral stricture, compression by lymphoceles, implantation stenosis, vesicoureteral reflux, and late-occurring transitional cell carcinoma at the implantation site. Static MRU was able to diagnose or exclude a dilation of the graft collecting system. It visualized the course of the ureters and localized the obstruction site in four of five obstructed transplants. In one case the ureter was obscured by lymphoceles, which were demonstrated by hydrographic MRU as well. The definite cause for obstruction was provided in only 2 of 5 cases. Dilation due to vesicoureteral reflux could not be differentiated. The current multimodality approach to renal transplant imaging already provides comprehensive assessment of graft hydronephrosis. Static MRU may be useful in some cases since complications associated with intravenous iodinated contrast or antegrade pyelography can be avoided. Its main drawback, the lack of functional information, may be overcome by combining it with contrast-enhanced MRU.

Post Renal Transplant Surgical Complications; MRI Standard Applications and Diagnostic Outcomes

“…The sensitivity, specificity and overall accuracy for Gdenhanced MRU in detection of ureteral obstruction were 80%, 100% and 98.9% and for both heavy T 2 W and single-shot MRU they were 100%. These results concerning static heavy T 2 W MRU were comparable to those reported by Schubert et al (13) and were 80%, 100% and 98.8%.…”

MR urography of obstructive uropathy: diagnostic value of the method in selected clinical groups

“…"All-in-one approach" MR procedures, such as conventional sequences, MR angiography and MRU, are advocated for evaluation of renal transplants [28,29,30]. Insignificant nephrotoxicity of gadolinium chelates allows performance not only of sMRU but also excretory MRU in the patients after renal transplantation, even in those with increased level of creatinine (although it is suggested that the level of serum creatinine would not exceed 4 mg/dl).…”

MR Urography: Techniques and Clinical Applications

“…When examining renal transplants with MR urography, it is advantageous to combine static-fluid with excretory phase sequences, provided sufficient renal function is present. Schubert et al (65) studied nine renal transplant recipients with static-fluid MR urography and found the lack of functional information to be limiting. In their small series, static-fluid MR urography revealed a definite cause of obstruction in only two of five cases (65).…”

“…Schubert et al (65) studied nine renal transplant recipients with static-fluid MR urography and found the lack of functional information to be limiting. In their small series, static-fluid MR urography revealed a definite cause of obstruction in only two of five cases (65). Static-fluid MR urography may not be capable of helping to distinguish between ureteral obstruction and vesicoureteral reflux in some cases, and ureteral leak cannot be demonstrated in the absence of excreted contrast material.…”