Imaging of Pancreas Transplants: Postoperative Findings With Clinical Correlation Jonathan R. Dillman, MD,*Þ Khaled M. Elsayes, MD,Þ Ronald O. Bude, MD,Þ Joel F. Platt, MD,Þ and Isaac R. Francis, MDÞ Abstract: Pancreas transplantation has become more commonplace over the past several decades. Consequently, the radiological evaluation of patients with such transplants has also become more common. Radiologists must therefore be familiar with the normal imaging ap- pearances of pancreas transplant grafts as well as a wide variety of transplant-related complications. In this article, we review the cross- sectional imaging appearances of normal pancreas transplant grafts as well as present representative examples of complications associated with the procedure. Key Words: pancreas transplant, complication, ultrasound, computed tomography, magnetic resonance imaging (J Comput Assist Tomogr 2009;33: 609Y617) I n 1966, the first documented human pancreas transplant procedure was performed at the University of Minnesota. 1 Currently, pancreas transplantation is performed at approxi- mately 100 transplant centers in the United States. About 1400 procedures are performed annually in the United States (Fig. 1). 2 Pancreas transplantation is indicated for the treatment of insulin- dependent diabetes mellitus (or type 1). 3 The goals of pancreas transplantation include improved glycemic control without the need for exogenous insulin injections and prevention of diabetes mellitusYrelated complications. 4 This procedure may also par- tially reverse or stabilize diabetes-related complications, such as diabetic nephropathy and neuropathy. 3 Pancreas transplant procedures typically use a cadaveric graft and are most commonly performed in conjunction with renal transplantation. 4 This is because pancreas transplant graft survival is improved in the setting of a transplant kidney. 2,5 In the United States, 67% of pancreas transplantation procedures are simultaneous pancreas-kidney transplants, whereas approxi- mately 21% are pancreas-after-kidney transplants. 2 Twelve per- cent of procedures are isolated pancreas transplants (pancreas transplant alone), most commonly in the setting of nonuremic diabetes mellitus. 2 A variety of other factors have also helped to improve pancreatic transplant graft survival over the past several decades. These factors include refined surgical techniques, im- proved immunosuppressive regimens, and the creation of dedi- cated transplant centers. 4,6,7 SURGICAL TECHNIQUES Pancreatic transplant grafts are typically placed in an in- traperitoneal pelvic location using a midline incision. 7,8 After harvesting of the graft from the donor and before placement within the recipient, a pretransplantation arterial BY-graft[ is fashioned on the Bback-table[ from the donor’s common iliac, external iliac, and internal iliac arteries (Fig. 2). 7,8 This Y-graft is then sutured to the donor pancreatic graft. The donor superior mesenteric artery is anastomosed to the donor external iliac artery portion of the Y-graft, whereas the donor splenic artery is anastomosed to the donor internal iliac artery portion of the Y-graft. 4,7,9 Intraoperatively, the donor common iliac artery of the Y-graft is then anastomosed to a recipient iliac artery (common or external), whereas the donor portal vein is anas- tomosed to either a system vein (iliac vein, 85%Y90%) or the portal venous system (superior mesenteric vein, 10%Y15%). 6,8 Pancreatic graft exocrine secretions may be drained to either the small bowel or urinary bladder. 8 Today, most pancreas transplant procedures use enteric drainage with a surgical side- to-side anastomosis created between the donor duodenal segment and small bowel (duodenoenterostomy) (Fig. 3). Although previously favored, urinary bladder drainage with a surgical anastomosis created between the donor duodenal segment and the dome of the urinary bladder (duodenocysto- stomy) is now less commonly used (Fig. 4). Enteric drainage of pancreatic graft secretions has several advantages when compared with urinary bladder drainage. First, enteric drainage allows for physiological handling of pancreatic enzymes. Second, there are fewer metabolic complications associated with enteric drainage, including a lower incidence of metabolic acidosis (due to less bicarbonate loss). 8 Finally, the former method of drainage is associated with lower rates of urinary tract complications, such as hematuria, cystitis, urethri- tis, urethral stricture, and urethral perforation. 6,9Y11 It is not un- common for pancreas transplant grafts using urinary bladder drainage to be converted to enteric drainage months to years after transplantation because of the complications listed above. 6,9 Imaging of Pancreas Transplants Ultrasound, multidetector computed tomography (CT), and magnetic resonance imaging (MRI) are the primary imaging modalities used in the evaluation pancreas transplant grafts. 6 Ultrasound is the most commonly used imaging modality. 6 Ultrasound has several advantages over the other afore- mentioned imaging modalities in the evaluation of pancreas transplant grafts. These advantages include a lack of ionizing radiation, portability, and often excellent image quality due to superficial placement of the graft. Gray-scale imaging provides anatomic information pertaining to the graft itself and adjacent structures, whereas Doppler imaging provides information pertaining to the arterial and venous vasculature of the graft. 6 Consequently, ultrasound allows for diagnosis of numerous transplant-related complications. The primary disadvantages of ultrasound include its operator dependence and the fact that the graft may be poorly visualized because of a combination of adjacent bowel gas, overlying postoperative changes, and suboptimal sonographic window. 6 REVIEW ARTICLE J Comput Assist Tomogr & Volume 33, Number 4, July/August 2009 www.jcat.org | 609 From the *Section of Pediatric Radiology, C. S. Mott Children’s Hospital; and †Department of Radiology, University of Michigan Health System, Ann Arbor, MI. Received for publication August 21, 2008; accepted November 10, 2008. Reprints: Jonathan R. Dillman, MD, Department of Radiology, University of Michigan Health System, and Section of Pediatric Radiology, C. S. Mott Children’s Hospital, 1500 East Medical Center Dr, Ann Arbor, MI 48109 (e-mail: jonadill@med.umich.edu). Copyright * 2009 by Lippincott Williams & Wilkins 9 Copyright @ 200 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.