Power Doppler imaging and resistance index measurement in the evaluation of acute renal transplant rejection

This study was designed to test the hypotheses that power Doppler imaging has a predictive value in the assessment of acute renal allograft rejection and that the information garnered from the combination of resistance index (RI) determination and power Doppler imaging has an even greater predictive value in this assessment.Power Doppler images obtained prior to 96 sequential renal allograft biopsies in 92 patients with suspected renal transplant rejection were retrospectively graded for parenchymal vascularity on a scale of 1 to 4: 1, normal, uniform cortical flow; 2, mild peripheral cortical hypoperfusion; 3, vascular pruning in cortex and medulla; and 4, no visible parenchymal flow, with flow seen only in central vessels. Power Doppler grades and RIs for these cases were compared to graft biopsy results.No statistically significant association was observed between parenchymal vascularity as graded by power Doppler imaging, RI, and the presence of acute transplant rejection.Neither grading of vascularity on power Doppler images, RI measurement, nor the combination of these methods is an accurate means of detecting renal allograft rejection.