Objective: Most arteries in humans are directly surrounded by adipose tissue and it has been hypothesized that an excess of perivascular adipose tissue (PVAT) is involved in the pathogenesis of atherosclerosis and arterial stiffening. There is a lack of research examining the relationships between PVAT with other measures of arterial health (i.e., stiffness and wall thickness). The purpose of the current study was to examine relationships between the carotid PVAT measured through extra-medial thickness (EMT) ultrasonography and other measures of vascular health.

Methods: Central arterial stiffness by pulse wave velocity was obtained with applanation tonometry at the common carotid and femoral arteries, and common carotid artery intima-media thickness (IMT), compliance, distensibility and stiffness index were obtained with simultaneous sonographic imaging and applanation tonometry. Resting measures of heart rate and supine brachial blood pressure were also obtained. Carotid artery EMT and IMT measurements were sonographically imaged in the longitudinal section. Carotid EMT was denoted as the distance between the jugular intima-lumen interface to the carotid media-adventitia interface. Custom semi-automated edge detection software was used for image and data analysis.

Results: Data was collected from 20 healthy young adults (mean age 24.2 ± 13.8 yrs, 5 females). Carotid EMT was significantly correlated to brachial mean arterial pressure (r = 0.52, n = 18, p < 0.01), central pulse wave velocity (r = 0.45, n =20, p < 0.02), IMT (r = 0.55, n = 20, p < 0.01), and carotid stiffness index (r = 0.53, n =20, p < 0.01).

Conclusion: These preliminary findings indicate that an increased carotid PVAT may be associated with increases in both regional carotid and central arterial stiffness. Carotid EMT ultrasonography provides an additional tool that correlates significantly with the existing vascular health measures in this cohort. Further studies are needed to determine whether EMT will provide relevant additional information that can assist in the prediction of cardiovascular outcomes and the evaluation of risk reduction interventions.

Figure 1

Custom edge-detection software uses a region of interest (yellow box) and quantifies the common carotid artery extra-medial thickness measurement, indicated by the red dotted lines.