SPATIAL-DISTRIBUTION OF CAROTID INTIMAL-MEDIAL THICKNESS AS MEASURED BY B-MODE ULTRASONOGRAPHY

Background and Purpose Measurements of intimal-medial thickness (IMT) of the carotid artery by B-mode ultrasonography are widely used as mar kers of atherosclerosis. This report describes empirical features of t hese measurements to characterize their distribution within arterial w all segments, to explore their potential as study outcome measures, an d to examine their links with traditional risk factors for cardiovascu lar disease. Methods Sequential transverse measurements of IMT in the carotid arteries were made in 899 participants from the Asymptomatic C arotid Artery Progression Study (ACAPS) at baseline. Data from 17 intr asegment sites in each of 12 arterial wall segments were used to descr ibe patterns of thickness and visualization and to characterize cross- sectional area, severity, and roughness/irregularity by the intrasegme nt averages, maxima, and SDs of IMT, respectively. Results Serial corr elations of IMT measurements indicated localized and diffuse features of disease. The spatial distribution of IMT had two dominant features: overall mass and mass relative to roughness. The validity of these fe atures was demonstrated by their correlation to known risk factors for carotid atherosclerosis: body mass index, age, high-density lipoprote in cholesterol, systolic blood pressure, smoking, and sex. Conclusions Both the mean and maxima of intrasegment measurements appear to be go od candidates for use in clinical studies. B-mode ultrasonography has validity for the description of IMT roughness and shape. Both of these features are linked to cardiovascular risk factors, which supports th e multifaceted nature of atherosclerosis.