Pancreatic transplants: secretin-stimulated MR pancreatography

Secretin-stimulated MR cholangiopancreatography: spectrum of findings in pancreatic diseases

Abstract

MR cholangiopancreatography (MRCP) is an imaging technique that has evolved over the past 2 decades and that continues to have a fundamental role in the non-invasive detection of morphologic features of the pancreatic ducts. In several studies, MRCP has shown a good correlation with endoscopic retrograde cholangiopancreatography in the evaluation of diseases and anatomic variants of the pancreatic ductal system. However, in physiologic conditions the pancreatic ducts are not always easily recognisable. More recently, secretin-enhanced MRCP protocols have been developed for a more complete assessment of pancreatic ducts and glandular function, including monitoring of pancreatic flow dynamics and duodenal filling after pancreatic hormonal stimulation with secretin. The injection of this hormone causes temporary dilation of the pancreatic ducts, principally by increasing pancreatic exocrine secretions, and thus improving MRCP detection of the ducts and characterisation of pancreatic disorders and allowing the assessment of the exocrine pancreatic reserve. The purpose of this pictorial review is to summarise the technical aspects of secretin-stimulated MRCP, to report the secretin-stimulated MRCP findings of pancreatic duct abnormalities and to review the diagnostic capabilities of secretin-stimulated MRCP in various pancreatic ductal system conditions.

Main Messages

• MRCP has a fundamental role in the non-invasive detection of pancreatic ducts.

• In physiologic conditions pancreatic ducts are not always well detected on MRCP.

• Secretin injection causes temporary dilation of pancreatic ducts and thus improves MRCP detection.

• Secretin-stimulated MRCP may allow the assessment of the exocrine pancreatic reserve.

• Secretin increases the diagnostic capabilities of MRCP for evaluating pancreatic disorders.

Secretin-Stimulated Magnetic Resonance Imaging Assessment of the Benign Pancreatic Disorders: Systematic Review and Proposal for a Standardized Protocol

This systemic review summarizes the current literature and general consensus on secretin-stimulated magnetic resonance imaging (s-MRI) of the benign pancreatic disorders and discusses important aspects on how s-MRI is optimally performed. The aim is to provide an overview, for clinicians and radiologist, of the s-MRI protocols and the range of clinical applications. Furthermore, the review will summarize the criteria for evaluation of pancreatic morphology and function based on s-MRI.The literature search indentified 69 original articles and 15 reviews. Chronic pancreatitis was the disease that was most frequently assessed by s-MRI (33%), followed by acute pancreatitis (9%). Dynamic thick-slab 2-dimensional magnetic resonance cholangiopancreatography was the most used imaging sequence (86%). The diameter of the main pancreatic duct (75%) and pancreatic exocrine function based on visual grading of duodenal filling (67%) were the most evaluated pancreatic features. Sufficient similarities between studies were identified to propose the most agreeable standardized s-MRI protocol for morphological and functional assessment of the pancreas. In the future, more research and increased collaboration between centers is necessary to achieve more consensus and optimization of s-MRI protocols.

Early reexploration for suspected thrombosis after pancreas transplantation. Transplantation. 2011;91:902-907. [PMID: 21301398 DOI: 10.1097/tp.0b013e3182106069]

BACKGROUND

Graft thrombosis is the most common cause of early graft loss after pancreas transplantation. Early reexploration may permit salvage or timely removal of the thrombosed graft.

METHODS

This was a retrospective review of 345 pancreas transplants performed at a single center between January 2003 and December 2009. Early reexploration was defined as within 1 week of pancreas transplantation.

RESULTS

Of the 345 transplants, there were 35 early reexplorations. The graft was compromised in 20 cases (57%): 10 venous thromboses, 3 arterial thromboses, 2 combined arterial and venous thrombosis, 2 thromboses secondary to allograft pancreatitis, and 3 cases of positional ischemia without thrombosis. Of these allografts, three reperfused once repositioned and six were successfully thrombectomized for a graft salvage rate of 45%. One of the thrombectomized grafts remained perfused but never functioned and was removed at retransplantation. The 10 remaining compromised grafts that were deemed unsalvageable and required allograft pancreatectomy. Nine of these recipients were retransplanted (eight within 2 weeks) and one was not a retransplantation candidate.

CONCLUSIONS

Reexploration for suspected graft thrombosis after pancreas transplantation resulted in a negative laparotomy rate of 43%, but permitted graft salvage in 45% of compromised grafts.

Magnetic resonance imaging in pancreas transplantation

Magnetic resonance imaging (MRI) plays an important role in the evaluation of pancreas transplantation. Standard MRI, magnetic resonance angiography, and MR cholangiopancreatography can demonstrate the changes of the anatomy after transplantation. Vascular complications are assessed by MR angiography. Magnetic resonance cholangiopancreatography reveals ductal changes resulting from acute and/or chronic rejection and determines leaks with the use of a secretin-stimulated MR cholangiopancreatography. Serial contrast-enhanced MRI may detect the diminished perfusion that is related to the graft rejection or vascular complications. In this paper, we reviewed types of pancreas transplantation procedures, complications that arise in a short and/or a long term after the transplantation, and their assessment by MRI.