Doppler ultrasound in the diagnosis of renal transplant artery stenosis--value of resistive index.

Doppler ultrasound (DU) with angiographic correlation was performed in 19 hypertensive renal transplant recipients suspected for transplant artery stenosis. DU included calculation of the intrarenal resistive index (RI) and measurement of the maximum systolic velocity in the transplant artery. All 10 cases having a pathologically low RI (< or = 0.6) had a > or = 50% stenosis; specificity and positive predictive values were thus 100%. There were 5 false-negative diagnoses, sensitivity 67%. The measurement of maximum systolic velocity was feasible in only 15 cases (79%). Using a cut-off point of 2 m/s the sensitivity was 91% and there were 4 false-positive cases and one false-negative case. Balloon percutaneous transluminal angioplasty (PTA) was performed in 13 cases, of which 9 were successful. In all successful cases RI was < 0.6 after PTA. We conclude that low RI (< 0.6) is highly suggestive for transplant artery stenosis. RI may serve as an indicator of the hemodynamic success of PTA.