Three-dimensional segmentation and structural characterization of murine atherosclerotic plaques using contrast-enhanced microCT

Details

Supervisors

Kerckhofs, Greet ; Grootaert, Mandy

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil biomédical, à finalité spécialisée

Abstract

enAtherosclerosis is a chronic inflammatory disease and the leading cause of car- diovascular mortality worldwide. Accurate three-dimensional characterization of atherosclerotic plaques remains a challenge, as conventional 2D histology suffers from tissue destruction and sampling bias. This thesis evaluates the potential of contrast-enhanced micro-computed tomography (CECT) to visualize and quantify plaque architecture within the intact murine aortic root. Atherosclerosis was induced in female mice using the AAV8-mPCSK9 model combined with a high-fat diet over 10 weeks. Ex vivo CECT imaging was performed at a voxel size of 1.35 μm using Hf-WD POM 1:2 as a contrast-enhancing staining agent. A dedicated preprocessing and segmentation pipeline was developed in Avizo, combining intensity normalization, median and unsharp masking filters, marker-controlled watershed segmentation, and manual intensity thresholding to classify distinct tissue compartments. The resulting gray-level distributions were validated through qualitative corre- lation with Sirius Red histological sections obtained from biologically equivalent animals. The intensity classes identified in CECT were mapped to specific tissue components, including the lipid-rich necrotic core, the developing fibrous cap, the healthy vascular wall, and the dense elastic laminae of the tunica media. In the early stage group, a consistent volumetric expansion of the aortic wall was observed relative to healthy controls, accompanied by the emergence of lower attenuation density profiles associated with pathological remodeling. Quantitative morphometric indices, including plaque burden, necrotic core volume fraction, and core-to-cap ratio, revealed marked phenotypic heterogeneity within the cohort. Marked phenotypic heterogeneity was observed within the cohort, with lesion profiles ranging from lipid-dominant to transitional fibro-calcific configurations. These findings demonstrate that high-resolution CECT is a promising tool for the 3D morphometric profiling of atherosclerotic plaques in preclinical research.