Related Experiment Video
Updated: May 31, 2026
A Methodological Approach to Non-invasive Assessments of Vascular Function and Morphology
Published on: February 7, 2015
Inter-reader differences in common carotid artery intima-media thickness: implications for cardiovascular risk
Joseph F Polak1, Laurie C Funk, Daniel H O'Leary
1Department of Radiology, Tufts Medical Center, 800 Washington St, Box 299, Boston, MA 02111, USA. jpolak@tuftsmedicalcenter.org
Objectives:
Far wall common carotid artery intima-media thickness, a surrogate measure of atherosclerosis, requires the tracing of two carotid wall interfaces on ultrasound images: the lumen-intima and media-adventitia. Vascular age is derived from intima-media thickness measurements. We studied how tracing the wall interfaces affects intima-media thickness measurements and estimates of vascular age.
Methods:
Five readers made far-wall common carotid intima-media thickness measurements on 26 carotid artery images. Each reader traced lines at the lumen-intima and media-adventitia interfaces. An observer, blinded to reader identity and intima-media thickness values, reviewed the images and estimated the relative location of these lines compared to his judgment of the interface location: +1 for 1 pixel above the interface, 0 at the interface, and -1 if below. The significance of differences was evaluated by analysis of variance.
Results:
Mean intima-media thickness measurements ranged between 0.57 and 0.78 mm and showed significant differences between readers (P < .009). Differences in carotid intima-media thickness measurements made by the readers were significantly associated with the location of the media-adventitia interfaces (P < .0001) but not the lumen-intima interfaces (P = .07). The intima-media thickness differences corresponded to mean differences in estimated vascular age ranging from 14 to 21 years.
Conclusions:
Inter-reader differences in common carotid intima-media thickness measurements are mostly seen for the media-adventitia wall interface and are detectable by an experienced observer. These inter-reader differences affect the use of intima-media thickness measurements for cardiovascular risk evaluation, can cause substantial errors in vascular age estimates, and might be correctable by performing replicate readings of standard image sets.
