Two-dimensional vessel wall diffusion anisotropy of human carotids - A novel measure of vascular ageing?

Magnetic resonance (MR) diffusion tensor imaging (DTI) is a new, non-invasive method to investigate arterial vessel walls. High resolution diffusion weighted imaging (DWI) in combination with a two-dimensional (2D) diffusion gradient sampling scheme has recently been demonstrated as feasible for evaluating diffusivity in the vessel wall of human carotids. We aimed to identify associations of altered diffusivity in human carotids with presence or absence of cardiovascular disease, body mass index (BMI), sex and age in a clinical setting.

In this single center case-control study we used DWI in combination with a 2D gradient in a 3 T MRI scanner to evaluate diffusivity parameters in carotid vessel walls of clinical patients with known cardiovascular disease (n = 17) and healthy controls (n = 21). We used a read-out segmented EPI (rs-EPI) sequence for DWI.

A group comparison showed significantly decreased fractional anisotropy (FA) in patients older than 60 years (p < 0.001) and in patients with a BMI higher than 25 (p = 0.019). Patients with cardiovascular disease had higher values for mean diffusivity (p = 0.005) than patients without cardiovascular disease. A multiple linear regression analysis showed age and sex to be associated with FA.

Two-dimensional vessel wall DTI of human carotids is feasible for clinical research. Besides patient age, we identified Sex, BMI, or the presence of cardiovascular disease as relevant factors for carotid vessel wall diffusivity. Decreased FA values might indicate early-stage atherosclerosis and vascular ageing.