Magnetic resonance microscopy diffusion tensor imaging of collagen fibre bundles stabilizing an atherosclerotic plaque of the common carotid artery

Imaging differences between stable and vulnerable lesions by means of magnetic resonance imaging (MRI) is challenging due to the high spatial resolution needed, to assess key features associated with plaque destabilization. Risk of plaque rupture is stratified based on fibrous cap thickness but might also be dependent on the presence of key features like lipid-rich necrotic core and intra-plaque haemorrhage. Moreover, collagen, the major component of the extracellular matrix and main load-bearing component of the artery, is also associated with the mechanical stability of an atherosclerotic plaque (fibrous cap). Post-mortem magnetic resonance microscopy diffusion tensor imaging (MRM-DTI) demonstrates for the first time the stabilization of an atherosclerotic plaque core of the common carotid artery by collagen bundles of the fibrous cap. Human carotid artery of a 59-year-old female patient was excised post-mortem within 18 h after death and fixed in Krebs–Henseleit solution. Magnetic resonance imaging measurements were performed on a 15.2 T preclinical MRI scanner (BioSpec 152/11). Scan parameters are described in Supplementary material. Panel A shows a schematic representation of the carotid artery with an arteriosclerotic plaque. The positions of the presented MRI slices are delineated by grey lines. Panel B shows the colour-coded fractional anisotropy (FA). Fractional anisotropy is a scalar value between zero and one indicating the magnitude of anisotropy for the diffusion of water protons. The colour code indicates the direction of diffusion with the convention red for left–right, green for up–down, and blue for anterior–posterior. Deterministic fibre tracking (Panel C) reveals the circumferential tissue structure of the carotid artery and demonstrates how the plaque is enclosed.