RELATIONS OF INTIMAL-MEDIAL THICKNESS AMONG SITES WITHIN THE CAROTID-ARTERY AS EVALUATED BY B-MODE ULTRASOUND

Background and Purpose B-mode ultrasound is a widely used technique fo r the clinical and epidemiological assessment of carotid atheroscleros is. This article describes the relation between arterial intimal-media l thickness (IMT) at different sites within the extracranial carotid a rtery. Methods IMT was measured by B-mode real-time ultrasound as an i ndex of atherosclerotic involvement in the extracranial carotid arteri es as part of the population-based Atherosclerosis Risk in Communities (ARIC) study. The relation between IMT at different sites was describ ed by correlation coefficients and percentile regression techniques ba sed on between 4034 and 9386 pairs of measurements (variation in sampl e size depending on the paired sites). Results Increased IMT at one si te was associated with increased IMT at other sites. The correlation b etween right and left IMT at the same anatomic location in the carotid artery ranged from .34 to .49; the correlation at different anatomic locations in the carotid artery on the same side ranged from .25 to .4 3. The distribution of IMT, described by the percentiles of IMT at the inference site as a function of IMT at the index site, showed constri cted percentiles of IMT at the inference site for small IMT at the ind ex site and an increase in the spread of percentiles with increasing I MT. Conclusions Although increased carotid IMT at one site is positive ly associated with thickened walls at other carotid sites, the ability to accurately predict wall thickness at a site given the wall thickne ss at other sites is modest. The general association between sites sup ports the systemic nature of atherosclerosis, while the lack of tight agreement between sites supports the focal nature of the atherosclerot ic process.