Contrast-Enhanced Quantitative Intravascular Elastography: The Impact of Microvasculature on Model-Based Elastography

Abstract

Model-based intravascular ultrasound elastography visualizes the stress distribution within vascular tissue – information that clinicians could use to predict the propensity of atherosclerotic plaque rupture. However, there are concerns that clusters of microvessels may reduce the accuracy of the estimated stress distribution. Consequently, we have developed a contrast-enhanced intravascular ultrasound system to investigate how plaque microvasculature impacts the performance of model-based elastography. In simulations diameters of 200,400, and 800 microns were used, where the latter diameter represented a cluster of microvessels. In phantoms, we used a microvessel with diameter of 750 microns. Peak stress errors of 3% and 38% were incurred in the fibrous cap when stress recovery was performed with and without a priori information about microvessels geometry. The results demonstrate that incorporating geometrical information about plaque microvasculature obtained with contrast-enhanced ultrasound imaging improves the accuracy of estimates of the stress distribution within the fibrous cap precisely.

Model-based vascular elastography improves the detection of flow-induced carotid artery remodeling in mice

“…Vascular elastography is an emerging ultrasound method for visualizing the biomechanical properties of vascular tissues. It measures strain or displacements induced in arteries in response to the pulsating blood pressure 7 – 9 , information that when combined with continuum mechanical modeling can produce spatial maps of the intrinsic biomechanical properties 44 – 46 . Several groups, including ours, are investigating the feasibility of using elastography to improve the detection of rupture-prone atherosclerotic plaques 15 , 25 , 26 .…”

“…Therefore, absolute Young’s modulus values may not represent arterial stiffness changes during each cardiac cycle. We used a nonlinear optimization algorithm to estimate Young’s modulus from the measured displacements, which we have previously described 44 – 46 ; therefore, we will provide only a brief description of the methodology. Young’s modulus was estimated by finding the distribution that minimized the difference between the measured tissue displacements ( ) and those computed with finite element model ( ).…”

Combining Subharmonic and Ultraharmonic Modes for Intravascular Ultrasound Imaging: A Preliminary Evaluation

“…However, the CTR of subharmonic images produced in these studies was comparable to fundamental imaging, likely due to the limited bandwidth of the transducer, and the lack of contrast agent-specific pulsing sequences. Recently, we demonstrated the feasibility of ultraharmonic IVUS imaging using commercially available catheters (Shekhar et al, 2016; Huntzicker et al, 2016) by implementing long duration chirp pulses to attain CTRs ranging from 11 – 18 dB. Although these results are encouraging, combining nonlinear imaging modes could improve the performance of CE-IVUS imaging substantially.…”