Wall irregularity rather than intima-media thickness is associated with nearby atherosclerosis.Ultrasound Med Biol 2009; 35(6):955-61UM
In addition to intima-media thickness (IMT), IMT inhomogeneity may carry information about atherosclerosis progression. In 147 vascular diseased patients (mean 66 y, 48% male), we determined the carotid bulb stenosis degree based on local Doppler blood flow velocities. Common carotid artery (CCA) morphologic characteristics, i.e. IMT, IMT-inhomogeneity (intraregistration variation) and IMT uni- and bilateral intrasubject variation (DeltaIMT), were measured using multiple M-mode. Associations of morphologic characteristics, stenosis degree and Framingham score were evaluated with Pearson correlation (r) and multiple regression analysis. The IMT distributions for subjects without and with stenosis were not similar. The stenosis degree score correlated significantly to unilateral (r=0.68) and bilateral DeltaIMT (r=0.62), IMT (r=0.41) and IMT-inhomogeneity (r=0.45). The averaged IMT and IMT-inhomogeneity increased slightly for singular stenosis and abruptly for multiple stenoses. Mean uni- and bilateral DeltaIMT per stenosis degree increased linearly with this degree, reaching a correlation close to 1 (r=0.98 and r=0.97). Interestingly, the majority of the subjects with a moderate to severe bulb stenosis exhibited a carotid IMT lower than the considered critical threshold of 0.9 mm. In conclusion, although CCA is not prone to plaques, its morphologic characteristics are positively correlated with stenosis degree score and other risk scores. DeltaIMT can be more reliable derived from inter-registration rather than from intra-registration variation. In the CCA, DeltaIMT substantiates vascular alteration better than IMT.