Reproducibility of brachial artery ultrasound measurement

Recent findings suggest that systemic artery endothelial function is associ ated with the preclinical phase of vascular disease and related to traditio nal atherosclerosis risk factors. Brachial artery diameter changes in respo nse to hyperemia have been proposed recently as a noninvasive tool to asses s endothelial function. To evaluate the reproducibility of brachial artery diameter measurements using ultrasound, rue studied 12 healthy subjects (ei ght men and four women, mean age 37 +/- 9 years). Art ATL HDI 3000 machine with a 5- to 10-MHz broadband transducer was used to image the right brachi al artery at rest, approximately 4 cm above the elbow. Gray scale ultrasoun d and color Doppler long-axis images were recorded. Brachial arterial outer diameter (i.e., from anterior adventitia to posterior adventitia) and inne r diameter (i.e., from anterior lumen-intima interface lo posterior lumen-i ntima interface) were measured in each subject by two observers. An offline analysis system was used to make measurements at end-diastole front four c ardiac cycles. Interobserver and intraobserver measurement variabilities (t echnical error rates) for brachial artery inner diameter were excellent, ra nging from 2.5% to 3.8%. However, interobserver technical error rates for o uter diameter measurements were significantly greater than those for inner diameter measurements, ranging from 16.3% to 22.1% (P < 0.001), presumably related to the difficulty in, accurately defining the adventitial lines. Th ere were no significant differences in interobserver and intraobserver vari ability for measurements made using gl-ay scale and color Doppler-aided tec hniques. We conclude that interobserver and intraobserver reproducibility, for brachial artery inner diameter measurements made from ultrasound images is excellent.