ACCURACY OF THE MAIN DOPPLER METHODS FOR THE EVALUATION OF THE CAROTID DEGREE OF STENOSIS - CW, PW AND COLOR DOPPLER

Objective :compare various Doppler methods for the quantification of t he degree of stenosis on 85 patients. Method:the following parameters were measured : maximal velocity (Vmax) inside the stenosis (PW), grad es of spectral disturbances at the outlet of the stenosis (PW-CW), ind ex of spectral disturbance (STI) at the outlet of the stenosis (PW-CW) , ratio of velocities I(IC/CC) in internal and common carotid (PW), ra tio of vessel cross section and residual lumen area (% STEN) by color Doppler. The reference method was the Grades of spectral disturbance a nd the index of stenosis measured post stenosis. (Method validated aga inst angiography and pieces of endarterectomy.) The following comparis ons were done: grades and STI by CW against grades and STI by PW, Vmax (PW) against grade and STI, % STEN (color) against grade and STI, % S TEN (color) against Vmax (PW), I(IC/CC) (PW) against grade and STI, I( IC/CC) (PW) against Vmax. Conclusion : (a) grades or stenosis index : showed the best reproductibility; (b) a high correlation was found bet ween the grades or stenosis index post stenosis measured by CW or PW; (c) V.max was not proportional to the stenosis degree and showed large fluctuations far the same stenosis degree: (d) the I(IC/CC) showed la rge fluctuations for the same stenosis degree, the correlation was poo r for this velocity ratio. Both Vmax and I(IC/CC) allow to detect only 2 groups of stenosis > 75 % or > 90 % in area; (e) color doppler over -estimate stenosis degree by approximatly 20 % but was more acurate an d reproducible than Vmax. An appropriate procedure was designed to avo id this over estimation.