Reproducibility of in vivo carotid intima-media thickness measurements: a review.

Abstract

The early phase of atherosclerosis can be studied by two-dimensional B-mode ultrasonography. Measurements of the combined thickness of the carotid intima and media arc currently used as intermediate outcome in clinical trials. Comparison of results between studies is difficult because of the different methods of image acquisition and analysis used. We review these methods and the reported reproducibility of intima-media thickness (IMT) measurements. Articles were collected using the MEDLINE literature search system and the references in the selected articles. Literature concerning human in vivo IMT measurements published in the English language in the period 1991 through 1995 was reviewed. A description of the methods of measuring IMT to determine intraobserver and/or interobserver variability was a prerequisite for inclusion. Twenty-three studies were included. Best reproducibility was found when measuring the mean IMT in the common carotid artery in more than one direction. We conclude that a consensus concerning the assessment of IMT is urgently needed. Variability of IMT measurements is lowest when determining the mean thickness in the common carotid artery in different directions.