Pancreas allograft rejection: correlation of transduodenal core biopsy with Doppler resistive index

To determine the usefulness of sonographically obtained resistive indexes (RIs) in the diagnosis of pancreas allograft rejection.

Findings were studied from 78 transduodenal pancreas allograft biopsies that were ultrasound-guided and cystoscopically directed. The 78 biopsies included 40 that were compared directly with baseline RI data. Biopsies were categorized by result and correlated with concurrent RIs (including 26 RIs obtained within 24 hours of biopsy) with the chi2 test for categoric variables and the Student t test for continuous variables. Sensitivity, specificity, and positive and negative predictive values were calculated with standardized formulas.

The mean RIs between the no rejection, mild acute rejection, and moderate acute rejection groups were not statistically significantly different; however, the mean RI associated with chronic rejection was statistically significantly higher (P < .05) than that in the other groups. The sensitivity, specificity, and positive and negative predictive values of either an elevated RI (> 0.70) or greater than 10% increase in the RI above the baseline value in the diagnosis of acute rejection were approximately 50%.

Neither the absolute level of the RI nor the relative increase was correlated with acute rejection proved at biopsy. Changes in RIs after pancreas transplantation were a poor indicator of acute rejection, but the absolute value of the RI was elevated in cases of chronic rejection.