Adhikary Shuvrodeb, Urban Matthew W, Guddati Murthy N
North Carolina State University, Raleigh, NC, USA.
Mayo Clinic, Rochester, MN, USA.
Ultrasound Med Biol. 2025 Aug;51(8):1160-1171. doi: 10.1016/j.ultrasmedbio.2025.03.002. Epub 2025 May 6.
Tissue viscoelasticity is becoming an increasingly useful biomarker beyond elasticity and can theoretically be estimated using shear wave elastography by inverting the propagation and attenuation characteristics of shear waves. Estimating viscosity is often more difficult than elasticity because attenuation, the main effect of viscosity, leads to poor signal-to-noise ratio of the shear wave motion. In the present work, we provide an alternative to existing methods of viscoelasticity estimation, based on peaks in the frequency-wavenumber (f-k) domain, which are considered more robust against noise compared with other features in the f-k domain. Specifically, the method minimizes the difference between simulated and measured versions of two sets of peaks (twin peaks) in the f-k domain, obtained first by traversing through each frequency and then by traversing through each wavenumber. The slopes and deviation of the twin peaks are sensitive to elasticity and viscosity, respectively, leading to the effectiveness of the proposed inversion algorithm for characterizing mechanical properties. This expected effectiveness is confirmed through in silico verification, followed by ex vivo validation and in vivo application, indicating that the proposed approach can be used effectively in accurately estimating viscoelasticity, thus potentially contributing to the development of enhanced biomarkers.
组织粘弹性正成为一种超越弹性的越来越有用的生物标志物，理论上可以通过对剪切波的传播和衰减特性进行反演，利用剪切波弹性成像来估计。估计粘度通常比估计弹性更困难，因为作为粘度主要效应的衰减会导致剪切波运动的信噪比很差。在本研究中，我们基于频率-波数（f-k）域中的峰值，提供了一种现有粘弹性估计方法的替代方法，与f-k域中的其他特征相比，这些峰值被认为对噪声更具鲁棒性。具体而言，该方法最小化了f-k域中两组峰值（双峰）的模拟版本和测量版本之间的差异，这两组峰值首先通过遍历每个频率获得，然后通过遍历每个波数获得。双峰的斜率和偏差分别对弹性和粘度敏感，从而使所提出的反演算法在表征力学性能方面具有有效性。通过计算机模拟验证、随后的离体验证和体内应用，证实了这种预期的有效性，表明所提出的方法可以有效地用于准确估计粘弹性，从而可能有助于开发增强型生物标志物。
