What is the role of CT and MRI in renal transplantation?
CT and MRI play an important role in the preoperative evaluation of renal transplant donors, as well as in the pre- and postoperative evaluation of recipients of renal transplants.
In potential renal donors, preoperative evaluation can be performed with three-phase dynamic contrast-enhanced CT or MRI to delineate the renal arterial, venous, and urothelial anatomy, because anatomic variations are common. This imaging evaluation is also performed to identify any incidental lesions in the abdomen or pelvis of the donors, which may need attention prior to surgery.
In potential renal transplant recipients, preoperative evaluation is helpful to delineate the underlying anatomy and to evaluate for preexisting renal disease. Renal transplants are usually placed in the iliac fossa with vascular anastomosis to the external iliac vasculature and ureteral implantation into the bladder.
Post-transplant evaluation in renal transplant recipients is primarily focused on the detection of vascular, renal parenchymal, or urothelial complications. Although ultrasonography (US) is often the initial imaging modality to evaluate these patients, CT and MRI may be used for problem-solving. Commonly encountered vascular complications following renal transplantation include thrombosis or stenosis of the transplant renal arteries or veins, renal arteriovenous fistula (AVF), and renal arterial pseudoaneurysm formation (the latter two are often a complication of percutaneous biopsy of a renal transplant). Commonly encountered urothelial complications following renal transplantation include ureteral obstruction and leak at the site of ureteral anastomosis to the urinary bladder; such urologic complications account for 10% of postoperative complications in renal transplants and are an important cause of transplant failure. Other important complications seen in renal transplants include urolithiasis, peritransplant fluid collection (abscess, hematoma, lymphocele, or urinoma), renal infarct, acute tubular necrosis (ATN), transplant rejection, and post-transplant lymphoproliferative disorder (PTLD).