Diagnosis of pancreatic transplant dysfunction: value of gadopentetate dimeglumine-enhanced MR imaging

Sixteen MR studies performed in four patients who had undergone combined pancreatic and renal transplantation were reviewed retrospectively to determine if dynamic gadopentetate dimeglumine-enhanced gradient-echo imaging is useful in the early diagnosis of pancreatic transplant rejection. The MR studies were performed between 3 days and 6 months after transplantation and consisted of T1- and T2-weighted spin-echo images as well as a gradient-echo image prior to administration of an IV bolus of gadopentetate dimeglumine (0.1 mmol/kg). After injection of gadopentetate dimeglumine, a static dynamic gradient-echo scan was obtained. Signal-intensity measurements were determined for each of the gradient-echo images and used to generate an enhancement curve. Because T2 values have previously been used as an objective indicator of rejection, the mean T2 of each pancreatic transplant was calculated also. The MR results were compared with clinical and laboratory data and/or percutaneous biopsy results. In six studies of normally functioning pancreatic allografts, the percent enhancement during the first minute of the enhancement curve was 98 +/- 23% (1 SD). In six episodes of acute dysfunction (rejection or infarction), the first-minute enhancement was 42 +/- 20%. In four cases of dysfunction, the finding of an abnormal enhancement curve preceded a significant drop in urinary amylase by 1-4 days. The calculated T2 value was prolonged in only two cases in which biopsy-proved pancreatic infarction had occurred. No prolongation of T2 was evident in four cases of rejection alone. These results suggest that mean T2 calculation at 1.5 T may not be a reliable indicator of pancreatic transplant rejection, but that gadopentetate dimeglumine-enhanced gradient-echo MR imaging of the pancreatic transplant may be a reliable early indicator of pancreatic transplant dysfunction.