The common carotid artery intima-media thickness (CCA-IMT) is usually measured using B-mode ultrasound images. A different approach for CCA-IMT detection is based on radio frequency (RF) multiple M-line analysis.
The present study explores the relationship between B-mode and RF measurement of CCA-IMT, as well as the reproducibility of both methods in 136 patients recently diagnosed with cardiovascular disease. Within one session, repeated measurements were made in the distal CCA bilaterally, using the B-mode (averaged over 10 mm) and RF technique (averaging 12 M-lines over 14 mm).
The two methods correlate well (Pearson r = 0.765). The CCA-IMT values measured with B-mode and RF were 0.779 +/- 0.196 mm and 0.734 +/- 0.172 mm, respectively. B-mode CCA-IMT is significantly larger than RF CCA-IMT (mean difference of 0.045 mm, SEM 7.8 microm; t = 5.82; p < 0.001). In the multivariate regression analysis, carotid artery stenosis, inhomogeneous IMT and diabetes mellitus were the main predictors of differences between B-mode and RF CCA-IMT. The intrapatient variation for B-mode and RF-based CCA-IMT is comparable (0.05 +/- 0.04 mm and 0.07 +/- 0.05 mm, respectively).
CCA-IMT values measured with RF and B-mode have similar reproducibility and exhibit acceptable correlation, but RF CCA-IMT is significantly smaller. The difference between both methods is mainly due to advanced atherosclerosis. Hence, both methods can be used reliably to measure CCA-IMT in clinical practice.