Inter-reader differences in carotid intima-media thickness measurements ranged from 0.57 to 0.78 mm (P<0.009) and were significantly associated with media-adventitia interface location (P<0.0001).
Observational (n=26)
Single-blind
How do inter-reader differences in tracing wall interfaces affect common carotid artery intima-media thickness measurements and vascular age estimates?
Significant inter-reader variability in carotid intima-media thickness measurements, primarily driven by media-adventitia interface tracing, can cause substantial errors in vascular age estimates.
p-value: p=<0.009
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.
Polak et al. (Fri,) conducted a observational in Atherosclerosis (n=26). Tracing of carotid wall interfaces vs. Different readers was evaluated on Mean intima-media thickness measurements (p=<0.009). Inter-reader differences in carotid intima-media thickness measurements ranged from 0.57 to 0.78 mm (P<0.009) and were significantly associated with media-adventitia interface location (P<0.0001).