Quantitative assessment of power Doppler mapping in the detection of renal allograft complications

We evaluated the usefulness of power Doppler (PD) imaging with a quantitative parameter in the identification of renal transplant complications.

One hundred eight transplanted kidneys were subjected to PD examinations. The blood flow area ratio (BFAR), defined as the percentage of the area of color pixels within a given cross-sectional area placed over a region of a transplanted kidney, was measured using built-in color histogram software and used as a quantitative parameter for evaluating the status of allograft blood perfusion. The mean BFARs in the normal, acute rejection (AR), acute tubular necrosis (ATN), chronic rejection (CR), and cytomegalovirus infection (CMV) groups were compared.

The BFAR in the normal group tended to decrease gradually with the time interval since transplantation, but the mean value, 0.68+/-0.08, was 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 < 0.01 for all). When a BFAR of 0.60 or greater was used as the diagnostic criterion for normal allografts, a sensitivity, specificity, and accuracy of more than 90% could be achieved in the diagnosis of complications. However, owing to overlapping BFARs among the complication groups, the BFAR alone had a limited ability to differentiate the types of complications.

Although PD imaging has some limitations in identifying the nature of renal allograft complications, the use of the quantitative parameter BFAR in the PD assessment of renal allografts may be useful in detecting complications. Further studies are needed to explore the BFAR's clinical value.