Reproducibility of various sonographic Doppler velocity parameters of the carotid arteries

Purpose: To assess the intraobserver variability of echoDoppler sonographic measurement of various carotid arteries parameters. Materials and methods: Repeated bilateral carotid examinations were perform ed in ten healthy subjects, using three color-coded duplex ultrasound syste ms (two Acuson 128 XP, one ATL HDI 3000) and different linear probes. Each examination included two successive sets of measurements. Results: The resistive index values decreased from the proximal common caro tid artery to the distal common carotid artery (p < 10(-7)). According to t he set of measurements and to the equipments considered, the range of mean absolute differences of the systolic peak velocity (PSV), the end diastolic velocity (EDV) values, the ICA/CCA PSV and PSV/EDV velocity ratios and the resistive index (RI) values were 8-16cm/s, 3-6cm/s, 0.08-0.15 and 0.16-0.2 6, and 0.02-0.06 respectively. Standard deviations of the proportional diff erences of the RI and PSV measurements averaged respectively 6% and 15% and were always reduced by repeating the measurements. The use of similar ultr asound machines was not associated with a reduced variability. Conclusion: The substantial variability of Doppler measurements in carotid arteries, even with the use of the same operator and similar machines could be reduced using "angle independent" parameters.