Abstract
Atherosclerotic plaques can gradually develop in certain arteries. Disruption of fibrous tissue in plaques can result in plaque rupture and thromboembolism, leading to heart attacks and strokes. Collagen fibrils are important tissue building blocks and tissue strength depends on how fibrils are oriented. Fibril orientation in plaque tissue may potentially influence vulnerability to disruption. While X-ray scattering has previously been used to characterize fibril orientations in soft tissues and bones, it has never been used for characterization of human atherosclerotic plaque tissue. This study served to explore fibril orientation in specimens from human plaques using small angle X-ray scattering. Plaque tissue was extracted from human femoral and carotid arteries, and each tissue specimen contained a region of calcified material. 3D collagen fibril orientation was determined along scan lines that started away from and then extended towards a given calcification. At locations several millimeters or more from a calcification, fibrils were found to be oriented predominantly in the circumferential direction of the plaque tissue. However, in a number of cases, the dominant fibril direction changed markedly near a calcification, from circumferential to longitudinal. Further study is needed to elucidate how these fibril patterns may change plaque tissue behavior.
Fundamental building blocks of nanoporous networks from ultra-small-angle x-ray scattering (USAXS) and small-angle x-ray scattering (SAXS) experiments
