G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado, USA.
Ultrasound Med Biol. 2021 Mar;47(3):787-798. doi: 10.1016/j.ultrasmedbio.2020.11.019. Epub 2020 Dec 25.
We investigate guided (Lamb) waves in a human cadaver skull through experiments and computational simulations. Ultrasonic wedge transducers and scanning laser Doppler vibrometry are used respectively to excite and measure Lamb waves propagating in the cranial bone of a degassed skull. Measurements are performed over a section of the parietal bone and temporal bone spanning the squamous suture. The experimental data are analyzed for the identification of wave modes and the characterization of dispersion properties. In the parietal bone, for instance, the A wave mode is excited between 200 and 600 kHz, and higher-order Lamb waves are excited from 1 to 1.8 MHz. From the experimental dispersion curves and average thickness extracted from the skull computed tomography scan, we estimate average isotropic material properties that capture the essential dispersion characteristics using a semi-analytical finite-element model. We also explore the leaky and non-leaky wave behavior of the degassed skull with water loading in the cranial cavity. Successful excitation of leaky Lamb waves is confirmed (for higher-order wave modes with phase velocity faster than the speed of sound in water) from 500 kHz to 1.5 MHz, which may find applications in imaging and therapeutics at the brain periphery or skull-brain interface (e.g., for metastases). The non-leaky A Lamb wave mode propagates between 200 and 600 kHz, with or without fluid loading, for potential use in skull-related diagnostics and imaging (e.g., for sutures).
我们通过实验和计算模拟研究了人体颅骨中的导波（兰姆波）。分别使用超声楔形换能器和扫描激光多普勒测振仪来激励和测量在去气颅骨的颅骨中传播的兰姆波。在跨越鳞缝的顶骨和颞骨部分进行测量。对实验数据进行分析以识别波模式并表征色散特性。例如，在顶骨中，在 200 至 600 kHz 之间激励 A 波模式，并且在 1 至 1.8 MHz 之间激励更高阶的兰姆波。从实验色散曲线和从颅骨 CT 扫描中提取的平均厚度，我们使用半解析有限元模型估计平均各向同性材料特性，这些特性捕获了基本的色散特性。我们还探讨了颅骨去气后在颅腔中加水时的漏波和非漏波行为。从 500 kHz 到 1.5 MHz 成功激励了漏波兰姆波（对于高于声速的高阶波模式），这可能在大脑外围或颅骨-脑界面的成像和治疗中找到应用（例如，用于转移）。非漏 A 兰姆波模式在有或没有流体加载的情况下在 200 至 600 kHz 之间传播，可用于颅骨相关诊断和成像（例如，用于缝合线）。
