Quantitative assessment of power Doppler mapping in the detection of renalallograft complications

Purpose. We evaluated the usefulness of power Doppler (PD) imaging with a q uantitative parameter in the identification of renal transplant complicatio ns. Methods. One hundred eight transplanted kidneys were subjected to PD examin ations. The blood flow area ratio (BFAR), defined as the percentage of the a rea of color pixels within a given cross-sectional area placed over a reg ion of a transplanted kidney, was measured using built-in color histogram s oftware and used as a quantitative parameter for evaluating the status of a llograft blood perfusion. The mean BFARs in the normal, acute rejection (AR ), acute tubular necrosis (ATN), chronic rejection (CR), and cytomegaloviru s infection (CMV) groups were compared. Results. The BFAR in the normal group tended to decrease gradually with the time interval since transplantation, but the mean value, 0.68 +/- 0.08, wa s significantly higher than that in the complication groups: AR, 0.43 +/- 0 .18; ATN, 0.43 +/- 0.14; CR, 0.15 +/- 0.14; and CMV, 0.36 +/- 0.10 (p < 0.0 1 for all). When a BFAR of 0.60 or greater was used as the diagnostic crite rion for normal allografts, a sensitivity, specificity, and accuracy of mor e than 90% could be achieved in the diagnosis of complications. However, ow ing to overlapping BFARs among the complication groups, the BFAR alone had a limited ability to differentiate the types of complications. Conclusions. Although PD imaging has some limitations in identifying the na ture of renal allograft complications, the use of the quantitative paramete r BFAR in the PD assessment of renal allografts may be useful in detecting complications. Further studies are needed to explore the BFAR's clinical va lue. (C) 1999 John Wiley & Sons, Inc.