Acute pancreatic transplant rejection: Evaluation with dynamic contrast-enhanced MR imaging compared with histopathologic analysis

PURPOSE: To evaluate the use of dynamic contrast material-enhanced gradient-recalled-echo MR imaging for the diagnosis of acute pancreatic transplant rejection, as confirmed at histopathologic analysis. MATERIALS AND METHODS: Thirty MR imaging studies were performed in 25 patients within 3 days of percutaneous biopsy or pancreatectomy. The mean percentage of parenchymal enhancement (MPPE) at dynamic contrast-enhanced MR imaging was calculated. RESULTS: Biopsy findings were no evidence of rejection (n = 7 [23%]), mild rejection (n = 10 [33%]), moderate (n = 6 [20%]) and severe (n = 2 [7%]) acute rejection, and infarction (n = 5 [17%]). The corresponding MPPEs at 1 minute were 106%, 66%, 62%, 57%, and 3%, respectively. Overlap of cases in the normal and rejection groups occurred; however, using an MPPE cutoff of 100% resulted in a sensitivity of 96%. An MPPE over 120% was seen in the normal group only. The MPPE was significantly greater in the normal group than in the rejection or infarction group (P < .05). CONCLUSION: Dynamic contrast-enhanced MR imaging is highly sensitive for the detection of acute pancreatic transplant rejection. Because of overlap of cases in the normal and rejection groups, percutaneous biopsy may be needed in some cases. Pancreatic allografts with infarction can be clearly identified.