Accuracy of Renal Perfusion by Transplant DTPA Scintigraphy in Predicting Rejection: A Retrospective Analysis
AIM: The study aimed to assess the utility of transplant perfusion in predicting rejection on renal scintigraphy.
METHOD: Retrospective analysis was carried out on all renal transplant DTPA scans performed in our department over the preceding 3 years, where biopsies were performed within 4 weeks of scintigraphic examination. Two nuclear medicine physicians blinded to transplant outcomes classified transplant perfusion as ‘normal’, ‘mild’, ‘moderate’ or ‘severely’ impaired. Perfusion was classified as normal when the maximum renal activity was observed within 3 seconds of the maximum iliac arterial activity. It was classified as mild, moderate and severely impaired when the maximum transplant activity was observed within 3-6, 6-12 and > 12 seconds respectively. These results were then correlated with the transplant biopsy results.
RESULTS: A total of 80 examinations in 54 patients were available for analysis (males 31/54). Two examinations were excluded from analysis, as the tracer bolus was fragmented, which precluded accurate assessment. Of the 78 examinations 58 were cadaveric transplants, 15 living related, & 5 non-related living donors.
DTPA perfusion Histology normal Histology- rejection
Normal 37 14
Abnormal 19 8
Abnormal perfusion was a poor predictor in diagnosing transplant rejection as was presence of normal perfusion in excluding rejection. Using abnormal perfusion as a predictor of rejection the PPV was 30%, NPV 72%, and overall accuracy 58%. Normal perfusion excluded rejection with a specificity of only 66%.
CONCLUSION: Transplant perfusion, judged by visual analysis on DTPA renal scintigraphy is a poor predictor in diagnosis or exclusion of transplant rejection