The geometry and stiffness of a vessel are pertinent to blood dynamics and vessel wall mechanical behavior and may alter in diseased conditions. Ultrasound-based ultrafast Doppler (uDoppler) imaging and shear wave imaging (SWI) techniques have been extensively exploited for the assessment of vascular hemodynamics and mechanics. Their performance is conventionally validated on vessel-mimicking phantoms (VMPs) prior to their clinical use. Compared with commercial ones, customized VMPs are favored for research use because of their wider range of material properties, more complex lumen geometries, or wall structures. Fused deposition modeling (FDM) 3D printing technique with plastic filaments is a promising method for making VMPs with a complex vessel lumen. However, it may require a toxic solvent or a long dissolution time currently. In this paper, we present a safe, efficient and geometrically flexible method where FDM 3D printing with a water-soluble polyvinyl alcohol (PVA) filament is exploited to fabricate a walled three-branch VMP (VMP-I). As a key step in fabrication, to avoid dissolution of the PVA-printed vessel core by the solution of the tissue-mimicking material, paraffin wax was used for isolation. Paraffin wax is easy to coat (i.e. without any special equipment), of satisfactory thickness (∼0.1 mm), chemically stable, and easy to remove after fabrication, thus making the proposed method practicable for ultrasound imaging studies. VMP-I was examined by B-mode imaging and power Doppler imaging (PDI) to verify complete dissolution of PVA-printed vessel core in its lumen, confirming good fabrication quality. The flow velocities in VMP-I were estimated by uDoppler imaging with a -0.8% difference, and the shear wave propagation speeds for the same phantom were estimated by SWI with a -6.03% difference when compared with fluid-structure interaction (FSI) simulation results. A wall-less VMP of a scaled and simplified coronary arterial network (VMP-II) was additionally fabricated and examined to test the capability of the proposed method for a complex lumen geometry. The proposed fabrication method for customized VMPs is foreseen to facilitate the development of ultrasound imaging techniques for blood vessels.

中文翻译：

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使用带有水溶性细丝的3D打印进行超声成像的壁状血管模拟体模：设计原理，流固耦合（FSI）模拟和实验验证。

血管的几何形状和刚度与血液动力学和血管壁机械行为有关，并且在患病情况下可能会发生变化。基于超声的超快多普勒（uDoppler）成像和剪切波成像（SWI）技术已被广泛用于评估血管血流动力学和力学。在临床上使用之前，通常先在模仿血管的模型（VMP）上验证其性能。与商业化的VMP相比，定制的VMP具有广泛的材料特性，更复杂的管腔几何形状或壁结构，因此更适合用于研究。具有塑料细丝的熔融沉积建模（FDM）3D打印技术是一种用于制造具有复杂血管腔的VMP的有前途的方法。但是，当前可能需要有毒溶剂或较长的溶解时间。在本文中，我们提出了一种安全，有效和几何灵活的方法，其中利用水溶性聚乙烯醇（PVA）细丝进行FDM 3D打印来制造壁式三分支VMP（VMP-1）。作为制造中的关键步骤，为了避免组织模拟材料溶液溶解PVA印刷的血管芯，使用石蜡进行隔离。石蜡易于涂覆（即，无需任何特殊设备），具有令人满意的厚度（约0.1 mm），化学稳定并且在制造后易于去除，因此使该方法可用于超声成像研究。通过B模式成像和功率多普勒成像（PDI）检查了VMP-1，以验证PVA打​​印的血管核在其内腔中是否完全溶解，从而确认了良好的制造质量。通过uDoppler成像以-0估算VMP-1中的流速。与流体-结构相互作用（FSI）仿真结果相比，SWI估计相差8％，并且同一模型的剪切波传播速度相差-6.03％。此外，还制作了比例缩放和简化的冠状动脉网络（VMP-II）的无壁VMP，并对其进行了测试，以测试所提出方法对复杂内腔几何形状的能力。可以预见所提出的用于定制VMP的制造方法，以促进用于血管的超声成像技术的发展。此外，还制作并检查了缩放和简化的冠状动脉网络（VMP-II）的无壁VMP，以测试所提出方法对复杂管腔几何形状的能力。可以预见所提出的用于定制VMP的制造方法，以促进用于血管的超声成像技术的发展。此外，还制作并检查了缩放和简化的冠状动脉网络（VMP-II）的无壁VMP，以测试所提出方法对复杂管腔几何形状的能力。可以预见所提出的用于定制VMP的制造方法，以促进用于血管的超声成像技术的发展。