Power Doppler imaging of acute renal transplant rejection

Purpose We evaluated the usefulness of power Doppler imaging (PDI) in diagnosing acute renal‐transplant rejection. Methods Twenty‐eight patients underwent 33 renal‐transplant biopsies for suspected acute rejection. Patterns of renal parenchymal vascularity revealed by PDI in patients with abnormal biopsy results were compared with patterns in a group who had normal biopsy results. PDI examinations were reviewed retrospectively by 2 independent radiologists who had no knowledge of the biopsy results. A PDI diagnosis of acute rejection required marked vascular pruning in both the cortex and medulla. PDI results then were compared with transplant‐biopsy results. Results The sensitivity and specificity of PDI for diagnosing acute renal‐transplant rejection were 40% and 100%, respectively. None of the patients with negative biopsy results had PDI abnormalities. The negative predictive value of PDI was 33%, and the positive predictive value was 100%. Conclusions In our study, an abnormal sonogram was highly predictive of acute transplant rejection. However, a normal sonogram did not exclude the possibility of rejection. © 1999 John Wiley & Sons, Inc. J Clin Ultrasound 27:171–175, 1999.