Successful identification of acute renal allograft rejection with duplex ultrasonography

Duplex ultrasonography has met with variable accuracy in identifying acute renal allograft rejection. These published studies have focused on using mathematical indices. We have applied duplex ultrasonography differently by insonating the site of rejection, i.e. renal cortex, to identify by subjective analysis the changes of the velocity spectral patterns. This subjective analysis method was compared to the mathematical indices of diastolic/systolic ratio and pulsatility index in 126 episodes of clinical acute renal allograft rejection which all had biopsy correlation. This present study represents the largest published experience with duplex ultrasonography and renal transplant rejection. Subjective analysis of velocity spectral patterns (SUBJ) resulted in sensitivity of 87%, specificity of 94% and overall accuracy of 88%. This technique was statistically better than the diastolic/systolic ratio (DSR) sensitivity of 40%, specificity of 72% and overall accuracy of 49%, or the pulsatility index (PI) sensitivity of 47%, specificity of 75% and overall accuracy of 55%. The superior results of the subjective analysis technique of duplex ultrasonography to identify acute renal allograft rejection suggests that this diagnostic approach has sufficient accuracy to avoid invasive allograft biopsies.