Automated intima-media thickness: the Los Angeles atherosclerosis study

Common carotid artery (CCA) intima-media thickness (IMT) from B-mode ultrasound is a widely used measure of early atherosclerosis. This study evaluated within- and between-sonographer reproducibility of automated edge-tracking IMT using a low-cost mobile scanner. B-mode images of the left and right CCA were acquired on two occasions (interval of 2–14 days) by two sonographers for 38 subjects, aged 31–75 y. Reproduciblity error was measured as the mean absolute difference (MAD ± SEM) and the standard deviation of differences (SDΔ) between repeated measurements. Within-sonographer (MAD = 0.027 ± 0.006 mm; SDΔ = 0.044 mm) and between-sonographer errors (MAD = 0.041 ± 0.008 mm; SDΔ = 0.064) in IMT (mean = 0.74, SD = 0.14) of a single artery were small compared to those of other protocols. Combined averaging across both body positions and arteries reduced intersonographer MAD by 47% (MAD = 0.022 ± 0.003 mm; SDΔ = 0.029 mm). These data demonstrate that the proposed IMT protocol reduces reproducibility error by more than 50% relative to several protocols used in other major studies.