Haïat Guillaume, Sasso Magali, Naili Salah, Matsukawa Mami
CNRS, Laboratoire de Recherches Orthopediques, UMR CNRS 7052 B2OA, 10 avenue de Verdun, 75010 Paris, France.
J Acoust Soc Am. 2008 Sep;124(3):1811-21. doi: 10.1121/1.2950091.
Cortical bone quality is determinant in bone fragility and its ultrasonic evaluation has become possible in clinical practice. However, the interaction between a broadband ultrasonic pulse and this complex multiscale medium remains poorly understood. The frequency dependence of phase velocity, which may impact clinical measurements, has been sparsely investigated. Our objective is to evaluate the determinants of the frequency dependence of phase velocity in bovine femoral cortical bone samples using an in vitro ultrasonic transmission device. The apparent phase velocity varies quasilinearly on a 1 MHz restricted bandwidth around 4 MHz. After compensating for diffraction effects, significant differences in velocity dispersion are obtained according to the anatomical location. The microstructure of each sample is determined using an optical microscope, which allows assessing the dependence of dispersion on the type of bone microstructure. Mostly positive but also negative values of dispersion are measured. Negative dispersion is mainly obtained in samples constituted of mixed microstructure, which may be explained by phase cancellation effects due to the presence of different microstructures within the same sample. Dispersion is shown to be related to broadband ultrasonic attenuation values, especially in the radial direction. Results are compared with the local Kramers-Kronig relationships.
皮质骨质量是骨脆性的决定因素，其超声评估在临床实践中已成为可能。然而，宽带超声脉冲与这种复杂的多尺度介质之间的相互作用仍知之甚少。可能影响临床测量的相速度频率依赖性研究较少。我们的目标是使用体外超声传输装置评估牛股骨皮质骨样本中相速度频率依赖性的决定因素。在4MHz左右1MHz的受限带宽内，表观相速度呈准线性变化。在补偿衍射效应后，根据解剖位置可获得速度色散的显著差异。使用光学显微镜确定每个样本的微观结构，这有助于评估色散对骨微观结构类型的依赖性。测量得到的色散值大多为正值，但也有负值。负色散主要出现在由混合微观结构组成的样本中，这可能是由于同一样本中存在不同微观结构而产生的相消效应所致。结果表明，色散与宽带超声衰减值有关，尤其是在径向方向。将结果与局部克拉默斯 - 克朗尼格关系进行了比较。
