J Heart Stroke | Volume 4, Issue 1 | Research Article | Open Access
John Wikstrand*
Wallenberg Laboratory for Cardiovascular Research, Gothenburg University, Sweden
*Correspondance to: John Wikstrand
Fulltext PDFThe joint experience from many research laboratories around the world shows that high quality 2-D ultrasound images may be recorded from the common carotid artery and the carotid artery bulb. In most cases, the image from the carotid artery shows a typical double-line pattern similar in appearance from the near and far wall of the artery. In spite of the similarity of the near and far wall images the thickness of the intima-media complex can only be measured in a valid way in the far wall position. This is because it is only in the far wall that the intima-media complex is defined by leading edges from echoes of interest. In vitro experiments and measurements of arterial wall segment thicknesses obtained by histology and by vascular ultrasound also confirm that only far wall intima-media thickness, in contrast to near wall thickness, may be accurately measured. The anatomical location of a biological structure is always defined by a leading edge of an echo, and the thickness of a structure as the distance between the leading edges of two different echoes. If lumen diameter is measured in the carotid artery, this measurement should be carried out according to the leading edge principle. If changes in common carotid lumen diameter are observed in prospective studies, analyses of common carotid artery cross-sectional area may help in interpreting the results. In measurements of intima-media thickness it would seem advisable to focus on far wall common carotid artery and carotid artery bulb recordings. Our advice would be to define a composite mean of 10 mm sections from the far wall common carotid and far wall carotid artery bulb intima-media thickness as the primary outcome variable. We conclude that main outcome variables in ultrasound studies of atherosclerosis should be from the far wall. It would seem advisable to focus on far wall common carotid artery and carotid artery bulb intima-media thickness. It is likely that including near wall measurements and measurements from the internal carotid artery will decrease measurement precision and lead to increases in sample size in scientific studies; or even dilute positive results in an otherwise well designed study.
Wikstrand J. Comments on How to Perform Valid Ultrasound Measurements of Carotid Artery Intima- Media Thickness and Lumen Diameter. J Heart Stroke. 2019; 4(1): 1056.