CHARACTERIZATION BY ULTRASOUND--NONLINEARITY PARAMETER

本研究的目的是探讨超声 体内非线性参数B/A（B和A是 状态方程的第二项和第一项， 声压和材料密度）。 我们的初步研究表明 有关生物学参数的体外测定 包括组织模型。 我们通过两个独立的 方法，即，有限振幅法，包括测量 谐波和热力学方法涉及的测量 声速作为流体静压力的函数，如下：（1） 对于水溶液，B/A随溶质浓度几乎线性增加 （2）B/A对蛋白质的分子量相对不敏感， （3）B/A为6.5 ~ 11 （4）B/A显著降低 破坏组织的超细胞结构特征， 细胞结构的破坏。 因此重要的信息 关于组织的状态被认为包含在 非线性超声传播参数B/A。 建议在体内测定许多组织和器官的B/A 以及其不同的病理状态。 这被认为 在参数可用于诊断成像目的之前， 以及用于治疗性治疗计划，因为目前还不知道 血管系统参与决定B/A。 初步研究将 包括利用外化确定作为路径长度函数的B/A 为了建立一个数据库， 后续研究将 处理不需要手术准备的更先进的方法。 病理条件将被引入，以检查的范围， 从正常器官到病变器官的B/A的变化。 该研究要求， 设计和制造适当的换能器系统， 测量. 本研究的结果将详细说明在体内的B/A值， 正常和病理组织，长期目标是能够 将这些信息用于诊断和治疗目的。

It is the purpose of the proposed study to investigate the ultrasound nonlinearity parameter B/A in vivo (B and A being the coefficients of the second and first terms, respectively, of the equation of state relating acoustic pressure and material density). Our preliminary studies have concerned in vitro determinations of the parameter for biological materials, including tissue models. We have determined by two independent methods, viz., the finite amplitude method involving the measurement of harmonics and the thermodynamic method involving the measurement of the speed of sound as a function of hydrostatic pressure, the following: (1) B/A increases nearly linearly with solute concentration for aqueous solutions of proteins, (2) B/A is relatively insensitive to the molecular weight of the solute at fixed concentrations, (3) B/A ranges from 6.5 to 11 for various soft mammalian tissues, and (4) B/A decreases significantly with destruction of the supracellular architectural features of tissue and with destruction of cellular structure. Thus significant information regarding the state of the tissue is believed to be contained in the nonlinear ultrasonic propagation parameter B/A. It is proposed to determine B/A in vivo for a number of tissues and organs and for different pathological states thereof. This is considered essential before the parameter can be used for diagnostic imaging purposes and for therapeutic treatment planning as it is presently not known how the vascular system is involved in determining B/A. Initial studies will involve determining B/A as a function of path length utilizing exteriorized organs, for the purpose of developing a data base. Subsequent studies will deal with more advanced methods not requiring surgical preparations. Pathological conditions will be introduced to examine the range of variation of B/A from normal to diseased organs. The study requires that appropriate transducer systems be designed and fabricated to make the measurements. The results of this study will be details of in vivo values of B/A of normal and pathological tissues, with the long range goal of being able to utilize this information for diagnostic and therapeutic purposes.