Renal scintigraphy following kidney transplantation – ATN, Rejection, and More

Introduction: Discuss the role of nuclear medicine imaging in the evaluation of early and late renal transplant dysfunction. Describe renal scintigraphy findings in the evaluation of kidney transplant complications. Elucidate the potential role of FDG PET-CT in the assessment of renal transplants. Examine clinical nuclear scintigraphy and FDG PET CT cases of renal transplant complications including acute tubular necrosis (ATN), rejection, calcineurin inhibitor nephrotoxicity, urinary obstruction, vascular compromise, urinary leak, and infection.

Methods: Review of the current literature regarding kidney transplant complications and the role of nuclear medicine imaging in the evaluation of the transplanted kidney. Review of the characteristic nuclear medicine imaging findings in various etiologies of renal transplant dysfunction. Presentation of high-yield clinical cases of renal scintigraphy for renal transplantation.

Results: Renal scintigraphy has an essential role in helping to differentiate the etiology of early graft dysfunction including acute tubular necrosis (ATN), acute rejection, and immunosuppressive drug toxicity. It is an initial modality of choice in differentiating ATN from other causes of renal dysfunction and for follow-up of graft function. Complications of renal transplantation can include arterial thrombosis/stenosis, venous thrombosis, ureteral obstruction, and urine leak, which can also be evaluated by renal scintigraphy. Renal scintigraphy can confirm suspected urine leak and ureteral obstruction and provide complementary information in the setting of acute arterial thrombosis, acute venous thrombosis, and renal artery stenosis. FDG PET-CT can have a role in the evaluation of malignancy and infection in the setting of renal transplantation.

Conclusions: Nuclear medicine imaging is a clinically useful tool in the evaluation of renal transplant dysfunction, especially in the immediate postoperative setting. It is the modality of choice in the evaluation and follow-up of renal function when ATN is suspected. Renal scintigraphy provides valuable information in the evaluation of kidney transplant complications. It has a confirmatory role in evaluating potential urinary leak and ureteral obstruction. FDG PET-CT is a valuable tool in evaluating for infections and malignancies in the setting of kidney transplantation.