Friday, May 10, 2024
5/10/2024
SUMMARY Human fibroatheroma (FA) cap rupture leads to the formation of an occluding thrombus, myocardial infarction (MI) and sudden death in more than half a million Americans every year. A major determinant of plaque rupture risk is the atheroma cap thickness. However, there are several other factors that play an important role in the FA cap rupture, including atheroma morphology, biological environment, tissue composition and mechanical environment. Indeed, the underlying mechanisms for atheroma cap rupture are still insufficiently understood. Vascular calcification has emerged in recent years among the factors that play an important role in the stability of plaque rupture. We have demonstrated to date the existence of thousands of microcalcifications (µCalcs) primarily in non-ruptured human atheroma caps using µCT imaging, and that they behave as an intensifier of the background circumferential stress in the cap. In our currently funded NIH project 1R16GM145474-01 “Microcalcifications in Atherosclerotic Plaque”, the working hypothesis is that µCalcs in the FA cap has a major effect on the FA cap rupture threshold. Unfortunately, µCT imaging cannot be used for in vivo assessment of µCalcs in human subjects. Vascular and intravascular ultrasound, on the other hand, are non-ionizing approaches routinely used for the imaging of atheroma. Despite significant progress on intra/vascular imaging of atheroma using ultrasound, the presence of large calcifications in the atheroma produce shadowing artifacts, lowering the image quality and the detection of atheroma morphology, atheroma cap thickness and the presence of µCalcs. Also important, high-frequency ultrasound imaging allow us to acquire high resolution images, but they are highly sensitive to micromotion of the ultrasound probe, in particular for the imaging of speckles produced by small calcifications. To address these shortcomings, we propose developing a 3D ultrasound tomography imaging approach for enhanced imaging of human atheroma with calcifications. The ultrasound tomography approach is based on an automated scanning robotic system comprising two collaborative robotic arms, one full-field 3D snapshot sensor and one Programmable Logic Controller (PLC). The robotic system will allow us significantly reducing motion artifacts, blurring, and shadowing due to calcifications in atheroma. This image quality improvement will be achieved by implementing multi-angle compound ultrasound tomography, where the positioning of the emitter and receiver imaging array probes will be controlled by the scanning robotic system. If the proposed automated scanning approach is successful in providing improved images of atheroma with calcifications, we envision this approach could be translated to in vivo imaging of atherosclerotic plaques, and detection of µCalcs in carotid vessels.
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