Dynamic Properties of Biological Soft Tissues and Its Clinical Applications to Internal Organs

通常指出，软组织的动态特性可以为我们提供额外的力学信息。因此，它们可以作为正常和病理哺乳动物内脏的诊断方法之一，具有重要意义。本文提出了一种建立哺乳动物生物软组织动态特性鉴定的新方法。发展了它的理论原理，并探讨了可能的应用。在小均匀悬臂梁顶端附着线性生物软组织条，采用弹簧和阻尼器组合建模。这种生物软组织的动态特性是粘弹性的，并且对频率有很强的依赖性，通过振动吸收器对小悬臂梁的自由阻尼振动的能力来测量。实验测量了整个系统的固有频率和振动的对数衰减量。然后，通过强化理论分析，计算组织的弹性常数和粘滞阻尼系数，表征软组织的粘弹性特性。从人前列腺组织中取出的正常、肥大和癌变活检标本，证明了该方法的可行性。粘滞阻尼系数与弹性常数在正常和癌的情况下呈显著相关，而在肥厚的情况下呈负相关。在癌组织中，虽然它们有很好的相关系数，但范围很窄，这意味着它们因为癌细胞的存在而失去了协调结构和功能的能力。另一方面，正常细胞、癌变细胞和肥厚细胞的回归线梯度存在显著差异。这表明，黏性阻尼系数与弹性常数之间的关系为前列腺组织的诊断提供了有用的信息。并对正常大鼠和自发性高血压大鼠主动脉壁组织进行了检查，探讨高血压和衰老对主动脉壁组织力学性能的影响。结果表明，主动脉壁组织的动态弹性常数和粘滞阻尼系数的特征可以反映高血压和衰老的影响。动脉壁的物质适应和重塑的存在或缺乏可能是获得结果的主要原因。少

It is commonly pointed out that dynamic properties soft tissues can provede us additional mechanical informations. Therefore, they can be quite significant as one criteria for the method of diagnosis in normal and pathological mammalian internal organs. A new approach is presented here to establish identification for dynamic properties of mammalian biological soft tissues. Its theoreticla principles are developed and possible applications are also investigated. A linear biological soft tissue strip is attached at the tip of small uniform cantilever beam and is modeled by the combination of spring and dashpot. Dynamic properties of this biological soft tissue, which are viscoelastic and have strong dependence upon frequency, are measured as capabilities of vilbration absorber against free damped vibrations of the small cantilever beam. Natural frequency and logarithmic decrement of the vibrations of the whole system are experimentally measured. Then, by enforcing theoretical analysis, e … More lasticity constant and viscous damping coefficient of the tissue are computed to characterize viscoelastic properties of the soft tissues.The normal, hypertrophic and cancerous biopsy specimen, which are picked out from prostate tissue of human, have been used to demonstrate the feasibility of this method. There was a significant correlation between the viscous damping coefficient and elasticity constant in the case of normal and cancer, while in hypertrophic, there was negative correlation. In cancer tissues, though they have a good correlation coefficient, the range is quite narrow, which means that they lost the ability to coordinate structure and function because of the cancer cell. On the other hand, there exists distinctive differences in the gradient of regression line among normal, cancer and hypertrophic. These suggest that the relationships between viscous damping coefficient and elasticity constant provides useful information in diagnosis for the human prostate tissue.Also, aorta wall tissue of normal and the spontaneously hypertensive rat have examined to investigate influences of hypertension and aging upon mechanical properties of the aorta wall tissue. The results suggest that characteristics of dynamic elasticity constant and viscous damping coefficient of the aorta wall tissue can reflect effects of hypertension and aging. The presence or the lack of material adaptation and remodeling of arterial wall may play the main roll for the results obtained. Less