Transmural transverse stiffness estimation in vascular shear wave imaging: A simulation and phantom study

Abstract

Shear wave imaging has emerged as a potential non-invasive technique for the quantitative assessment of the arterial shear modulus. Nonetheless, the arterial elasticity estimation in the transverse direction has been overlooked compared with the longitudinal direction, and the estimated transmural stiffness has rarely been evaluated. Accurate depiction of the transverse stiffness across the thin arterial wall warrants comprehensive characterization in both normal and pathological conditions. This study estimated the transmural arterial shear modulus in both the longitudinal (l Long) and transverse directions (l Trans) using group (c T) and phase velocities (c ph) in finite element models and hollow cylindrical tissue-mimicking phantoms with various shape factors. The results were validated against mechanical testing. Zero-order antisymmetric Lamb wave and circumferential Lamb type wave models were considered in the longitudinal and transverse directions of the thin-walled hollow cylinder, respectively. The results derived from the model with the thin plate assumption confirmed that c T underestimated l Long and l Trans. Unlike the c ph-based l Long estimates that were in excellent agreement with measured values, the c ph-based l Trans estimates were found to be comparable to c ph-based l Long at the inner wall but increased radially outward. Transmural l Trans estimation using c ph was demonstrated to be feasible for thin-walled hollow cylinders but necessitated careful account of the wall geometry, in particular the shape factor. Published by AIP Publishing.

Extending arterial stiffness assessment along the circumference using beam-steered ARFI and wave-tracking: A proof-of-principle study in phantoms and ex vivo

“…Furthermore, the differential ability for stiffness is lower in the transverse than in the longitudinal view [22] , [43] , with a geometry-dependent effective wave speed resolution of 0.5 m/s [43] . Moreover, we only analyzed group velocities, which provide a less accurate stiffness quantification than phase velocities [22] , [29] , [41] , [43] , [44] , [45] . Phase velocity analysis could improve the sensitivity but is not trivial because the waves propagate along paths with different curvatures for each frequency.…”

“…2 d). Because a constant angular speed over all ellipses was expected [29] , angular wave velocities (in rad/s) were calculated instead of true wave velocities (in m/s). Subsequently, as a surrogate of a stiffness map, 360⁰ angular velocity maps were derived for every phantom rotation using two approaches: I) based on 0° acquisitions only and II) based on compounding of 0° and beam-steered acquisitions.…”

“…Although ARFI-induced wave velocity estimations in a transverse plane could enable stiffness estimation for the entire wall circumference, its application is still complicated. Multiple studies showed the feasibility to assess ARFI-induced wave propagation along the transverse vessel cross-section in phantoms and in ex and in vivo (carotid) arteries [22] , [25] , [26] , [29] , [30] , [31] , [32] , [33] . Additionally, differences in velocities of these waves were detectable in plaque phantoms between the soft plaque and stiff wall [25] and in vivo between vulnerable and stable carotid plaques [22] .…”

A New Model of Ultrasonic Guided Wave Propagation in Blood Vessels and Its Propagation Characteristics

“…The feasibility of the thin-layer soft model in the measurement of vascular elasticity was also verified through the experiment of polyurethane tubes and pig arteries [13]. Then, Guo [16] estimated the arterial shear modulus in longitudinal and transverse directions using this model in [15]. Li [17] also developed a method to solve the vascular elastic modulus based on the guided circumferential wave (GCW) in the thin-layer-based method.…”

Walled vessel-mimicking phantom for ultrasound imaging using 3D printing with a water-soluble filament: design principle, fluid-structure interaction (FSI) simulation, and experimental validation

“…Separately, ultrasound-based shear wave imaging (SWI) (Couade et al 2010) and pulse wave imaging (PWI) (Vappou et al 2010) have been demonstrated to be capable of noninvasively estimating the stiffness of the blood vessel wall, which alters in impaired cardiovascular conditions. Recently, SWI was further developed to estimate both the longitudinal and transverse stiffnesses of the artery (He et al 2017, Guo et al 2017 under various luminal pressures (Wang et al 2019), thus enabling comprehensive characterization of the arterial wall.…”