High Framerate Plane-Wave Variance of Acceleration and Vector Flow Imaging for the Characterization of Atherosclerotic Plaque Morphology and Assessment of Vascular Hemodynamics

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PROJECT SUMMARY The need for minimally invasive methods for screening early predictors of ischemic stroke are required to combat the increase in cardiovascular disease cases while reducing number of unnecessary carotid endarterectomies, which are invasive but preventative procedures to remove plaques. The current gold-standard for diagnosis, duplex ultrasound, is often used to detect heavily occluded vasculature, but simply noting the degree of stenosis is an insufficient measure of plaque rupture vulnerability. Acoustic Radiation Force Impulse (ARFI) ultrasound technique recently emerged as a potential method to separate vulnerable from stable plaques through delineation of plaque components. However, as the technique relies on emission of high intensity focused acoustic pulses, although nondestructive, the potential for tissue heating limits extended uses, while the long period of data collection increases opportunities for motion artifacts to corrupt data collection and physiological interpretation of results. The use of a new ultrafast ARFI imaging sequence to evaluate both plaque structure and surrounding hemodynamics may provide significant advancement in reducing acquisition time, reducing acoustic heating, and improving risk prediction. There exists overwhelming evidence that mechanics of plaque growth and rupture are governed by shear forces acting on the vessel walls. Monitoring the dynamics changes in shear stress in addition to more efficiently detecting plaque composition may prove a novel avenue for discerning at risk patients with vulnerable atherosclerotic plaques vs those with stable plaque phenotypes. We propose to further develop and characterize ultrasound parallel transmit sequences to image tissue in rapid succession and additionally detect multi directional blood flow around the vasculature. Combining the ARFI elastography, high framerate imaging, and flow information allows a real-time realizable assessment of the plaque environment throughout the entire cardiac cycle. Therefore, meeting the aims of the study will further develop diagnostic imaging tools for future stroke risk assessment.