Search

The aim of this study was to determine the accuracy of Doppler waveform characteristics in grading femoropopliteal stenoses and to determine the interobserver and intraobserver reproducibility of measuring the same waveform characteristics.Thirty patients with isolated areas of stenosis found by arteriography were evaluated by color duplex sonography. Each patient underwent scanning by two observers on two separate occasions. Each observer was blind to the other's results. Doppler spectra were recorded in areas where color change suggested the highest velocity and also at the nearest normal proximal area. Peak systolic velocity, spectral broadening, and waveform configuration were measured at each site.An increase in peak systolic velocity of more than 200% accurately predicted a 50% or greater reduction in luminal diameter on angiography (70% sensitivity, 96% specificity). The presence of spectral broadening and an abnormal waveform shape were found to correlate poorly with the degree of stenosis. Analysis of variance showed no significant difference between observers in velocity measurements (p = 0.78).We conclude that although stenoses of greater than 50% can be distinguished from minor stenoses, more precise definition of the degree of narrowing is unlikely. The good repeatability of the velocity ratio makes it an excellent tool for monitoring major changes in the progression of disease.

The improvement of management strategies in patients with intermittent claudication might depend on a better understanding of the natural history of femoral atherosclerosis. The grading of stenoses, the monitoring of their progression, and the assessment of response to treatment are critically dependent on a method's accuracy and variability. Duplex ultrasound imaging provides a noninvasive way of measuring localized disease, but there has been relatively little objective evaluation of its accuracy and reproducibility. The aim of this study was to evaluate the accuracy and variability of duplex velocity ratio measurements of stenosis.In a laboratory flow model of the femoral artery, 14 concentric and eccentric stenoses were examined five times by three sonographers. Measurements were then repeated with a standardized technique in which Doppler angle and aperture position were fixed, giving a total of 420 measurements.Velocity ratio showed good correlation with degree of stenosis, R2 = 0.996. Intraobserver variability was low, but interobserver variability was significant with more severe stenosis (p = 0.002, analysis of variance). Standardization of the technique did not improve accuracy or variability. The 95% confidence limit was +/- 20% for a single reading of velocity ratio for stenoses of50% diameter reduction.We conclude that duplex ultrasound imaging can be used to accurately grade arterial stenosis in this range, and the potential exists for noninvasive monitoring of the progression of preocclusive femoral atherosclerosis and its response to treatment. In addition, repeated measurements of velocity ratio over time should be made by the same observer.