Zacharias K, Balabanidou E, Hatzokos I, Rekanos I T, Trochidis A
Physics Division, School of Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
J Biomech. 2009 Mar 26;42(5):581-6. doi: 10.1016/j.jbiomech.2008.12.018. Epub 2009 Feb 24.
The primary aim of this work is to investigate the potential of nonlinear ultrasound for microdamage detection in human bone. Microdamage evaluation in human bone is of great importance, because it is considered a significant parameter for characterizing fracture risk. Experiments employing nonlinear acoustic vibro-modulation were carried out in human femoral trabecular specimens removed during surgery. A frequency mixing (inter-modulation) was observed between an ultrasound wave, propagating in the bone, and a low-frequency vibration applied directly to the bone specimens. The appearance of side frequencies, which are related to the vibrational excitation, around the fundamental ultrasound frequency manifests the modulation nonlinear phenomenon. Instead of inducing microdamage by mechanical fatigue loading, specimens with different degree of osteoporosis were used. The experiments demonstrated that osteoporotic bone exhibits stronger nonlinearity compared to healthy bone presenting significant increase of the modulation amplitude with increasing degree of osteoporosis. The obtained results indicate that, in contrast to conventional hysteretic nonlinearity, dissipative acoustic nonlinearity can be of significance in the generation of nonlinear modulation effects. In the proposed technique the size and the shape of samples are not crucial compared to nonlinear resonant ultrasound spectroscopy (NRUS). Furthermore, the method is sensitive to the presence of microdamage, non-invasive, easy to implement and most important, it can be proved valuable tool for in vivo bone damage characterization.
这项工作的主要目的是研究非线性超声在检测人体骨骼微损伤方面的潜力。人体骨骼微损伤评估非常重要，因为它被认为是表征骨折风险的一个重要参数。在手术中取出的人体股骨小梁标本上进行了采用非线性声振动调制的实验。在传播于骨骼中的超声波与直接施加于骨骼标本的低频振动之间观察到了频率混合（互调）现象。在基本超声频率周围出现的与振动激发相关的边频表明了调制非线性现象。实验没有采用机械疲劳加载来诱导微损伤，而是使用了不同骨质疏松程度的标本。实验表明，与健康骨骼相比，骨质疏松性骨骼表现出更强的非线性，随着骨质疏松程度的增加，调制幅度显著增大。所得结果表明，与传统的滞后非线性不同，耗散声非线性在非线性调制效应的产生中可能具有重要意义。在所提出的技术中，与非线性共振超声光谱法（NRUS）相比，样品的尺寸和形状并不关键。此外，该方法对微损伤的存在敏感、非侵入性、易于实施，最重要的是，它可以被证明是用于体内骨骼损伤表征的有价值工具。
