A correlation between direct and indirect Doppler ultrasonographic measures in transplant renal artery stenosis

Screening for transplant renal artery stenosis (TRAS) with Doppler ultrasonography (DUS) is increasingly used in the era of kidney transplantation. Direct Doppler study of the stenotic site is a time- consuming and difficult method that requires an angle of interrogation parallel to the vessel. The aim of this study was to assess the correlation between the direct-PSVs (peak systolic velocity at the stenotic site), PSVs/PSVi (PSVi, peak systolic velocity of the adjacent iliac artery)-and indirect-intrarenal arterial resistive index (RI), perfusion index (PI), acceleration time (AT)-DUS findings in the kidney transplant recipients with TRAS. We performed 26 DUS studies of both intrarenal and main renal arteries in 19 TRAS patients (who had PSVs > 150 cm/s, PSVs/PSVi > 2). The mean values of PSVs and PSVs/PSVi were 212 +/- 44.19 cm/s and 2.77 +/- 0.77, respectively. The mean intrarenal RI, PI, and AT were 0.48 +/- 0.065, 0.70 +/- 0.12, and 177.8 +/- 54.6 msec, respectively. A significant negative correlation was found between PSVs and intrarenal RI (Pearson correlation coefficient (r) = -0.4, two-tailed P = .043). No correlation was found between intrarenal PI or AT and the direct DUS findings (P > .05). With a cutoff level of 0.55 for intrarenal resistive index, the sensitivity of this parameter to detect proximal renal arterial stenosis was about 85%. Conclusively, PSVs and intrarenal RI were negatively correlated. Intrarenal resistive index can be used as an screening measure for detection of TRAS.