Quantitative susceptibility mapping of the human carotid artery: Assessing sensitivity to elastin and collagen ex vivo

Abstract Purpose The aim is to establish the relationship between carotid susceptibility and microstructural components in diseased carotid arteries. Methods Excised cadaveric carotid arteries ( n  = 5) were scanned using high‐resolution QSM at 7 Tesla. After ex vivo imaging, all samples were brought to histology and stained for elastin, collagen, cells, and calcium. An image registration pipeline was used in combination with semi‐quantitative, regional histology analysis to evaluate relationships between MRI and microstructural components. Results Weak, non‐significant ( p  > 0.05) correlations were found between all components and regional magnitude and R 2 * measurements. A significant, moderate negative correlation between the elastin fraction and regional magnetic susceptibility, r elastin  = −0.63 ( p  < 0.0001) was found, as well as a significant, moderate negative correlation between collagen and regional magnetic susceptibility, r collagen  = −0.59 ( p  < 0.0001). Conclusion Tissue magnetic susceptibility in diseased human carotid arteries was shown to be significantly correlated with the dominant microstructural components of pathological human cadaver samples—elastin and collagen. Knowing that elastin and collagen are disrupted in vascular disease progression, QSM offers clinically translatable potential for novel disease biomarkers.