Complications following pancreatic transplantations: imaging features

Pancreatic Transplantation: Surgical Anatomy and Complications

Pancreatic transplantation is a complex surgical procedure performed for patients with chronic severe diabetes, often performed in combination with renal transplantation. Vascular and exocrine drainage anatomy varies depending on the surgical technique. Radiology plays a critical role in the diagnosis of postoperative complications, requiring an understanding of grayscale/Doppler ultrasound as well as computed tomography and MR imaging. In this review, we detail usual surgical methods and normal postoperative imaging appearances. We then review the most common complications following pancreatic transplants, emphasizing diagnostic features of vascular (arterial/venous), surgical, and diffuse parenchymal pathologic conditions on multiple imaging modalities.

Unlocking the post-transplant microenvironment for successful islet function and survival

Islet transplantation (IT) offers the potential to restore euglycemia for patients with type 1 diabetes mellitus (T1DM). Despite improvements in islet isolation techniques and immunosuppressive regimes, outcomes remain suboptimal with UK five-year graft survivals (5YGS) of 55% and most patients still requiring exogenous insulin after multiple islet infusions. Native islets have a significant non-endocrine component with dense extra-cellular matrix (ECM), important for islet development, cell survival and function. Collagenase isolation necessarily disrupts this complex islet microenvironment, leaving islets devoid of a supporting framework and increasing vulnerability of transplanted islets. Following portal venous transplantation, a liver injury response is potentially induced, which typically results in inflammation and ECM deposition from liver specific myofibroblasts. The impact of this response may have important impact on islet survival and function. A fibroblast response and ECM deposition at the kidney capsule and eye chamber alongside other implantation sites have been shown to be beneficial for survival and function. Investigating the implantation site microenvironment and the interactions of transplanted islets with ECM proteins may reveal therapeutic interventions to improve IT and stem-cell derived beta-cell therapy.

Jejunal or Ileal Exocrine Drainage in Pancreas Transplantation: Impact on Gastrointestinal Function

OBJECTIVES

Pancreas transplant can have serious complications requiring salvage pancreatectomy, and surgical approaches should be carefully considered, with jejunal or ileal anastomoses most often employed. The jejunum may reduce gastrointestinal disturbance, whereas the ileum is more immunogenic. Proximal gastrointestinal anastomoses pose challenges with salvage pancreatectomy and creation of high-output stoma, often in the context of end-stage renal failure. Here, we compared outcomes between these techniques.

MATERIALS AND METHODS

We retrospectively analyzed patient records of simultaneous pancreas and kidney transplants at a single center between 2013 and 2015, with follow-up to 2020.

RESULTS

Our center performed 86 simultaneous pancreas and kidney transplants during the study period; 10 patients were excluded because of incomplete records of anastomosis type. Of included recipients, 59.2% were men (mean age 41.5 ± 8.4 y), 72.4% were donors after brain death, and 98.7% had received a first pancreas transplant. Forty-three simultaneous pancreas and kidney transplants were performed with ileal anastomosis and 33 with jejunal anastomosis. We found no significant differences in recipient or donor factors or immunosuppression regimen between anastomosis groups and no significant differences in overall patient, pancreas, or kidney graft survival or in gastrointestinal complications. Hospital length of stay was higher with ileal anastomosis (median 14 vs 19 days; P < .05), as was cold ischemic time (median 8:48 vs 9:31 hours; P < .05). Three patients required salvage pancre-atectomy and loop ileostomy formation with multiorgan support, prolonged intensive care unit stay, relaparotomy, and/or laparostomy.

CONCLUSIONS

Long-term outcomes were comparable between our patient groups. Catastrophic complica-tions occur in a minority of cases, requiring salvage surgery. More complications occurred with ileal anastomosis, but this approach allows graft pancreatectomy and formation of loop ileostomy, avoiding a more proximal stoma in clinically unstable patients. Further studies are needed to examine the impact of enteric anastomosis site.

Applicability and reproducibility of the CPAT-grading system for pancreas allograft thrombosis

PURPOSE

Although pancreas allograft thrombosis (PAT) incidence has progressively decreased, it remains the most common cause of early graft failure. Currently, there is no consensus on documentation of PAT, which has resulted in a great variability in reporting. The Cambridge Pancreas Allograft Thrombosis (CPAT) grading system has recently been developed for classification of PAT. In this study we aimed to assess the applicability and validate the reproducibility of the CPAT grading system.

METHODS

This study is a retrospective cohort study. Selected for this study were all 177 pancreas transplantations performed at our center between January 1 st, 2008 and September 1 st, 2018 were included.

RESULTS

A total of 318 Computed Tomography (CT) images was reevaluated according the CPAT system by two local radiologists. Inter-rater agreement expressed in Cohen's kappa was 0.403 for arterial and 0.537 for venous thrombosis. Inter-rater agreement, expressed in the Fleiss' kappa, within clinically relevant thrombosis categories was 0.626 for Grade 2 and 0.781 for Grade 3 venous thrombosis.

CONCLUSIONS

Although not perfect, we believe that implementation of the CPAT system would improve current documentation on PAT. However, it is questionable whether identification of a small Grade 1 thrombosis would be relevant in clinical practice. Furthermore, a good quality CT scan, including adequate phasing, is essential to accurately identify potential thrombus and extend after pancreas transplantation.

Influence of Peritoneal or Hemodialysis on Results of Simultaneous Pancreas and Kidney Transplant

OBJECTIVES

The influence of peritoneal dialysis on outcomes after simultaneous pancreas and kidney transplant is still vague. In addition, whether peritoneal dialysis leads to a higher risk of infectious complications and higher mortality rates in these transplant patients has not been unambiguously confirmed. In this study, our aim was to verify whether dialysis type determined outcomes on the pancreas graft and whether dialysis type was a risk factor for graftectomy or recipient death.

MATERIALS AND METHODS

Our study group included 44 simultaneous pancreas and kidney transplant patients. Analyzed parameters included type and duration of dialysis treatment, age, sex, long-term pancreas graft survival and patient survival, overall mortality, and number of graftectomies.

RESULTS

Of 44 patients, 3 (7%) required a graftectomy. Mortality rate of the group was 5%. Of 44 patients, 33 had hemodialysis and 11 had peritoneal dialysis. In those who had hemodialysis, the mean duration of renal replacement therapy was 30.5 months, which was significantly longer than duration for those who had peritoneal dialysis (20.4 mo; P < .01). There were 3 graftectomies and 1 death in the hemodialysis group. In the peritoneal dialysis group, there were no graftectomies and 1 death, with no significant differences in the number of graftectomies and mortality rates between the groups. Long-term survival also did not differ between the groups.

CONCLUSIONS

We found that type of dialysis did not affect outcomes in our group of simultaneous pancreas and kidney transplant patients. Before transplant, each patient requires an individual approach to treatment. The type of dialysis performed should not be viewed as a contradiction for transplant.

Pancreatic allograft thrombosis: Suggestion for a CT grading system and management algorithm

Pancreatic allograft thrombosis (PAT) remains the leading cause of nonimmunologic graft failure. Here, we propose a new computed tomography (CT) grading system of PAT to identify risk factors for allograft loss and outline a management algorithm by retrospective review of consecutive pancreatic transplantations between 2009 and 2014. Triple-phase CT scans were graded independently by 2 radiologists as grade 0, no thrombosis; grade 1, peripheral thrombosis; grade 2, intermediate non-occlusive thrombosis; and grade 3, central occlusive thrombosis. Twenty-four (23.3%) of 103 recipients were diagnosed with PAT (including grade 1). Three (2.9%) grafts were lost due to portal vein thrombosis. On multivariate analysis, pancreas after simultaneous pancreas-kidney transplantation/solitary pancreatic transplantation, acute rejection, and CT findings of peripancreatic edema and/or inflammatory change were significant risk factors for PAT. Retrospective review of CT scans revealed more grade 1 and 2 thromboses than were initially reported. There was no significant difference in graft or patient survival, postoperative stay, or morbidity of recipients with grade 1 or 2 thrombosis who were or were not anticoagulated. Our data suggest that therapeutic anticoagulation is not necessary for grade 1 and 2 arterial and grade 1 venous thrombosis. The proposed grading system can assist clinicians in decision-making and provide standardized reporting for future studies.

Imaging of Pancreas Transplantation and Its Complications

Whole pancreas transplantation is an effective treatment for obtaining euglycemic status in patients with insulin-dependent diabetes mellitus, and is usually performed concurrent with renal transplantation in the affected patient. This article discusses complex surgical anatomical details of pancreas transplantation including surgical options for endocrine and exocrine drainage pathways. It then describes several possible complications related to surgical factors in the immediate post operative period followed by other complications related to systemic issues, vasculature, and the pancreatic parenchyma.

US Findings in Patients at Risk for Pancreas Transplant Failure

Purpose To determine if ultrasonographic (US) findings, including Doppler US findings, are associated with subsequent pancreas transplant failure. Materials and Methods A cohort of adult patients who underwent pancreas transplantation at a tertiary institution over the course of 10 years (from 2003 to 2012) was retrospectively evaluated for failure, which was defined as return to insulin therapy or surgical graft removal. The institutional review board provided a waiver of informed consent. All US images obtained within the 1st postoperative year were reviewed for three findings: arterial flow (presence or absence of intraparenchymal forward diastole flow), splenic vein thrombus, and edema. These findings were correlated with pancreas graft failure within 1-year after surgery by using Cox proportional hazards models and hazard ratios. Results A total of 228 transplants were included (mean patient age, 41.6 years; range, 19-57 years; 122 men, 106 women). Absent or reversed arterial diastolic flow was identified in nine of 20 failed transplants (sensitivity, 45%; 95% confidence interval [CI]: 23, 68) and in 15 of 208 transplants that survived (specificity, 93% [193 of 208]; 95% CI: 89, 96). The Cox proportional hazard ratio was 6.2 (95% CI: 3.1, 12.4). Splenic vein thrombus was identified in 10 of 20 failed transplants (sensitivity, 50%; 95% CI: 27, 73) and in 25 of 208 transplants that survived (specificity, 88% [183 of 208]; 95% CI: 83, 92). The Cox proportional hazard ratio was 4.2 (95% CI: 2.4, 7.4). Edema had the lowest specificity (Cox proportional hazard ratio, 2.0; 95% CI: 1.3, 2.9). In the multivariate analysis, only absent or reversed arterial diastolic flow remained significantly associated with transplant failure (adjusted hazard ratio, 3.6; 95% CI: 1.0, 12.8; P = .045). Conclusion Absent or reversed diastolic arterial Doppler flow has a stronger association with transplant failure than does splenic vein thrombus or edema. (©) RSNA, 2016.