Background: The aim of the present study was to ascertain in vascular diseased patients the morphological characteristics of the common carotid artery (CCA), i.e. intima-media thickness (IMT) and IMT ipsi- and bilateral intrasubject variation (DIMT) and to relate them to the carotid bulb stenosis degree score to establish the relevance of each parameter.

Methods: In 154 patients, referred to the vascular laboratory for CCA examination (mean 66 years, 48% male), the carotid bulb was visualized in Doppler-mode to rate the stenosis degree based on blood flow velocities. CCA IMT and ΔIMT were measured using multiple M-mode images (covering 3 heart beats). The association of morphological characteristics with stenosis degree was evaluated with Pearson correlation (r).

Results: Ipsi- and bilateral ΔIMT were stronger associated to stenosis degree score (r=0.67 and r=0.60, respectively, with p<0.001) than IMT (r=0.40, p<0.001). The averaged IMT increased slightly for stenosis degree<5 and abruptly for the two highest values (r=0.93, p=0.001). Mean ipsi- and bilateral ΔIMT presented a consistent graded increase with stenosis degree over the entire range (0–7), reaching a correlation close to 1 (r=0.98 and r=0.97, respectively, p<0.001).

Discussion: Although CCA is a region less prone to plaques, the morphological characteristics of CCA are positively correlated with stenosis degree score. The present study indicates that ipsi- and bilateral ΔIMT exhibit a stronger relation than IMT to the severity of carotid artery stenosis, underlining that ΔIMT carries different information than IMT. In conclusion, in the CCA, ΔIMT rather than IMT substantiates patient risk evaluation.