Imperial College London, Department of Bioengineering, London, SW7 2AZ, United Kingdom.
King's College London, Department of Biomedical Engineering, London, SE1 7EH, United Kingdom.
J Biomed Opt. 2013 Dec;18(12):121511. doi: 10.1117/1.JBO.18.12.121511.
Tissue viscosity is correlated with tissue pathological changes and provides information for tissue characterization. In this study, we report an optical method to track continuous shear-wave propagation at centimeter depths in an optically turbid medium. Shear-wave attenuation coefficients were measured at multiple frequencies using shear-wave laser speckle contrast analysis (SW-LASCA) to quantitatively estimate tissue viscosity using the Voigt model. Shear waves were generated within tissue-mimicking phantoms by an amplitude-modulated ultrasound (modulation frequency: 100 to 600 Hz) and tracked by time-resolved laser speckle contrast difference received on a charged-coupled device camera. Averaged contrast difference over a selected time window was related to shear-wave amplitude and used to calculate the shear-wave attenuation coefficient. Phantoms of varying viscosities (0.1 and 0.3 Pa s) were studied. Attenuation coefficients for different shear-wave frequencies (100 to 600 Hz) were calculated. Derived viscosity values had a maximum standard deviation of 9%, and these values were consistent with the independent measurements reported in a previous study using nonoptical methods.
组织粘度与组织病理变化相关，并为组织特征化提供信息。在这项研究中，我们报告了一种光学方法，用于在光混浊介质中跟踪厘米深度的连续剪切波传播。使用剪切波激光散斑对比分析（SW-LASCA）在多个频率下测量剪切波衰减系数，以使用 Voigt 模型定量估计组织粘度。通过幅度调制超声（调制频率：100 至 600 Hz）在组织模拟体中产生剪切波，并通过在电荷耦合器件相机上接收的时分辨激光散斑对比度差异进行跟踪。在选定的时间窗口上对平均对比度差异进行相关，以获得剪切波幅度，并用于计算剪切波衰减系数。研究了不同粘度的体模（0.1 和 0.3 Pa·s）。计算了不同剪切波频率（100 至 600 Hz）的衰减系数。得出的粘度值的最大标准偏差为 9%，这些值与之前使用非光学方法进行的独立测量一致。
