Sebastian Joseph A, Chérin Emmanuel, Strohm Eric M, Gouveia Zach, Boyes Aaron, Santerre J Paul, Démoré Christine E M, Kolios Michael C, Simmons Craig A
Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada; Translational Biology and Engineering Program, Ted Rogers Center for Heart Research, Toronto, Ontario, Canada.
Sunnybrook Research Institute, Toronto, Ontario, Canada.
Ultrasound Med Biol. 2025 Sep;51(9):1604-1613. doi: 10.1016/j.ultrasmedbio.2025.06.007. Epub 2025 Jul 7.
High-frequency ultrasound elastography (USE) can measure the mechanical properties of biomaterials and engineered tissues in vitro. Previously developed USE systems have been limited by contact acoustic radiation force (ARF) excitations and insufficient spatiotemporal resolution for sub-millimetre sub-surface mechanical property measurements.
We present a novel high-frequency USE system with a highly focused (f-number 1) 15 MHz ARF excitation transducer and a broadband (f-number 3) 40 MHz ARF tracking transducer.
When comparing shear moduli measured via USE with shear rheometry, shear moduli of 1% and 5% agar-silica phantoms estimated by USE, were 8.8 ± 2.2 kPa and 117.0 ± 12.3 kPa (8.0 ± 0.4 kPa by rheometry, p = 0.573 for 1%; 114.4 ± 7.2 kPa, p = 0.777 for 5%) and oil-agar silica phantoms were 105.0 ± 3.4 kPa (0%) and 77.0 ± 22.1 kPa (10%) by USE (101.0 ± 4.8 kPa by rheometry; p = 0.311 for 0%; 75.8 ± 5.3 kPa; p = 0.938 for 10%). The speed of sound, acoustic impedance, and acoustic attenuation of these samples were also determined. We also used in silico analysis to mimic our experimental system and analyze the spectral content of the resulting shear waves in elastic and viscoelastic tissues with parametric changes to the ARF excitation duration, shear modulus, and viscosity. Notably, we observed a nonlinear dependency of shear wave frequency on ARF excitation duration and material properties, where shear wave frequency was most sensitive to tissue elastic modulus at longer ARF durations but more sensitive to tissue viscosity at shorter ARF durations.
Our system enables noninvasive, nondestructive estimation of the mechanical properties of thin biomaterials via focused axial localization of the ARF, opening new avenues for future USE applications in engineered tissue systems.
高频超声弹性成像（USE）可在体外测量生物材料和工程组织的力学性能。先前开发的USE系统受到接触式声辐射力（ARF）激发以及亚毫米级表面下力学性能测量时空分辨率不足的限制。
我们展示了一种新型高频USE系统，该系统具有高度聚焦（f数为1）的15 MHz ARF激发换能器和宽带（f数为3）的40 MHz ARF跟踪换能器。
将通过USE测量的剪切模量与剪切流变仪测量结果进行比较时，USE估计的1%和5%琼脂-二氧化硅仿体的剪切模量分别为8.8±2.2 kPa和117.0±12.3 kPa（流变仪测量值为8.0±0.4 kPa，1%时p = 0.573；114.4±7.2 kPa，5%时p = 0.777），油-琼脂二氧化硅仿体通过USE测量分别为105.0±3.4 kPa（0%）和77.0±22.1 kPa（10%）（流变仪测量值为101.0±4.8 kPa；0%时p = 0.311；75.8±5.3 kPa；10%时p = 0.938）。还测定了这些样品的声速、声阻抗和声衰减。我们还进行了计算机模拟分析，以模拟我们的实验系统，并分析在弹性和粘弹性组织中，随着ARF激发持续时间、剪切模量和粘度的参数变化，所产生剪切波的频谱内容。值得注意的是，我们观察到剪切波频率对ARF激发持续时间和材料特性存在非线性依赖性，其中在较长的ARF持续时间下，剪切波频率对组织弹性模量最为敏感，而在较短的ARF持续时间下，对组织粘度更为敏感。
我们的系统能够通过ARF的聚焦轴向定位对薄生物材料的力学性能进行无创、无损估计，为未来USE在工程组织系统中的应用开辟了新途径。
