DIAGNOSIS OF RENOVASCULAR DISEASE BY EXTRARENAL AND INTRARENAL DOPPLER PARAMETERS

It is still a matter of debate as to which parameters should be used f or noninvasive diagnosis of renovascular disease by renal Doppler sono graphy (RDS). The accuracy of RDS in the detection of renal artery ste nosis (RAS) was tested in 95 consecutive, moderate to severe hypertens ive patients (I-II World Health Organization [WHO] stages). Reno-aorti c ratio (RAR) for peak systolic velocity (PSV) was also calculated to assist in the diagnosis of significant (>50%) RAS. Paired receiver-ope rating characteristic (ROC) analysis was plotted for evaluating the re lationship between sensitivity and specificity for each parameter. In a subset of 57 kidneys, the influence of blood pressure and age on int raparenchymal parameters was evaluated. Measurements of maximal peak s ystolic velocity (PSV) at the site of stenosis, RAR for PSV, and minim um acceleration index in the main renal artery showed high accuracy (a reas under the ROC curve 0.97, 0.88, and 0.80, respectively). Among in traparenchymal parameters, early systolic acceleration showed the best area under the ROC curve (0.90), but provided a low positive predicti ve value (29%) and was significantly influenced by blood pressure (mul tiple r=0.56; p=0.001). Pulsatility and resistive indices were found t o be less powerful as absolute values, and both significantly influenc ed by blood pressure and age (multiple r = 0.60 and 0.50; p=0.001, p=0 .02, respectively). However, interindividual variance of intrarenal in dices should be minimized by calculation of side difference, although this procedure would become misleading or impossible in patients with bilateral RAS or a single kidney, respectively. These results support the use of extraparenchymal parameters for noninvasive detection of RA S, and emphasize that intrarenal parameters cannot be considered as ab solute values.