Pruijssen Judith T, Fekkes Stein, Menssen Jan, de Korte Chris L, Hansen Hendrik H G
Medical Ultrasound Imaging Center (MUSIC), Department of Medical Imaging/Radiology, Radboud University Medical Center, Nijmegen, the Netherlands.
Physics of Fluid Group, MESA+ Institute for Nanotechnology, and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, the Netherlands.
Comput Struct Biotechnol J. 2023 Aug 26;21:4288-4300. doi: 10.1016/j.csbj.2023.08.024. eCollection 2023.
To fully quantify arterial wall and plaque stiffness, acoustic radiation force impulse (ARFI)-induced wave-tracking along the entire vessel circumference is desired. However, attenuation and guided wave behavior in thin vessel walls limits wave-tracking to short trajectories. This study investigated the potential of beam-steered ARFI and wave-tracking to extend group velocity estimation over a larger proportion of the circumference compared to conventional 0° ARFI-induced wave-tracking.
Seven vessel-mimicking polyvinyl alcohol cryogel phantoms with various dimensions and compositions and an human carotid artery were imaged in a dedicated setup. For every 20⁰ phantom rotation, transverse group wave velocity measurements were performed with an Aixplorer Ultimate system and SL18-5 transducer using 0⁰/20⁰/-20⁰-angled ultrasound pushes. Transmural angular wave velocities were derived along 60⁰-trajectories. A 360⁰-angular velocity map was composed from the top-wall 60⁰-trajectories 0°-data, averaged over all physical phantom rotations (reference). For each phantom rotation, 360⁰-angular velocity maps were composed using 0°-data (0⁰-approach) or data from all angles (beam-steered approach). Percentages of rotations with visible waves and relative angular velocity errors compared to the reference map as function of the circumferential angle were determined for both approaches.
Reference 360°-angular velocity maps could be derived for all samples, representing their stiffness. Beam-steering decreased the proportion of the circumference where waves were untraceable by 20% in phantoms and 10% , mainly at 0° push locations. Relative errors were similar for both approaches (phantoms: 10-15%, : 15-35%).
Beam-steering enables wave-tracking along a higher proportion of the wall circumference than 0⁰ ARFI-induced wave-tracking.
为了全面量化动脉壁和斑块的硬度，需要沿整个血管圆周进行声辐射力脉冲（ARFI）诱导的波追踪。然而，薄血管壁中的衰减和导波行为将波追踪限制在短轨迹上。本研究调查了与传统的0° ARFI诱导波追踪相比，波束控制ARFI和波追踪在更大比例的圆周上扩展群速度估计的潜力。
在一个专门的装置中对七个具有不同尺寸和成分的模拟血管的聚乙烯醇冷冻凝胶体模和一条人体颈动脉进行成像。对于体模每旋转20°，使用Aixplorer Ultimate系统和SL18-5换能器，通过0°/20°/-20°角度的超声推动进行横向群波速度测量。沿60°轨迹得出透壁角波速度。从顶壁60°轨迹0°数据组成360°角速度图，对所有体模的物理旋转进行平均（参考）。对于每个体模旋转，使用0°数据（0°方法）或所有角度的数据（波束控制方法）组成360°角速度图。确定两种方法中可见波旋转的百分比以及与参考图相比作为圆周角函数的相对角速度误差。
可以为所有样本得出参考360°角速度图，代表它们的硬度。波束控制使体模中波无法追踪的圆周比例降低了20%，在人体颈动脉中降低了10%，主要是在0°推动位置。两种方法的相对误差相似（体模：10 - 15%，人体颈动脉：15 - 35%）。
与0° ARFI诱导的波追踪相比，波束控制能够沿更高比例的血管壁圆周进行波追踪。
