A methodological study of arterial wall function using ultrasound technique

We aimed to establish reference values for three important properties of the arterial wall using a conventional ultrasound scanner. We measured: (1) intima-media thickness (IMT) of the carotid arteries with the internal trace function of the ultrasound system; (2) wall stiffness by pulsatile diameter changes in the right common carotid artery assessed by M-mode; and (3) endothelial function expressed as flow-mediated dilatation (FMD) of the brachial artery. IMT and wall stiffness measurements and reproducibility were compared with those obtained by external analysing systems. All variables were obtained in healthy subjects (n = 20), 29-53 years old. IMT increased with age (P < 0.01). There was no difference in IMT between men and women. The inter-operator variability for measuring IMT was 6-9%. The same order of reproducibility was obtained with an external PC-based analysing system. Regarding wall stiffness, no correlation was found with age, nor any difference between men and women. A low intra-operator variability (CV < 10%) was found for measurements of wall stiffness with both M-mode and an external wall tracking system. FMD of the brachial artery diminished with age (P < 0.01). There was a relation between FMD and brachial artery size (P < 0.01) and, therefore, as men have larger arterial diameters (P < 0.01), smaller FMD in men. We conclude that it is possible to characterize arterial wall function non-invasively in an adequately reproducible manner using a conventional ultrasound system in healthy middle-aged men and women.