Elasticity imaging of polymeric media.
Elasticity imaging of polymeric media.
复制标题
聚合物介质的弹性成像。
DOI：
10.1115/1.2540804
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Insana,MichaelF
中科院分区：
文献类型：
--
作者：
Sridhar,Mallika;Liu,Jie;Insana,MichaelF
软组织和水聚合物的粘弹性取决于连接聚合物基质和周围流体的分子结合力的强度。诊断成像的基础是疾病过程以改变组织的可测量刚度和粘度的方式改变分子尺度的键合。本文综述了线性粘弹性理论在明胶水凝胶中的应用，目的是制定软性生物组织中弹性成像的分子尺度解释方法。比较在不同几何形状下获得的测量结果，我们研究了在不同成像条件下获得的粘弹性参数的局限性。准静态（步进保持和低频谐波）刺激应用于凝胶在蠕变和应力松弛实验在受限和无受限几何显示连续的，双峰分布的响应时间。在响应的线性范围内，明胶将表现得更像固体或流体，这取决于刺激的大小。明胶可以从低阶流变模型的几个参数进行统计描述，这些模型是粘弹性成像的基础。只有当获得的蠕变数据大于最高延迟时间常数的两倍并且消除了任何稳态粘性响应时，才能获得成像参数的无偏估计。发现弹性应变和延迟时间图像在明胶中提供对比度和信号强度的最佳组合。延迟时间表示响应机械刺激的快速流体流动和缓慢基质重组的平均行为。就明胶模拟其他聚合物而言，如柔软的生物组织，弹性成像可以为受疾病影响的结缔组织的复杂结构和生化特征提供独特的见解。
Viscoelastic properties of soft tissues and hydropolymers depend on the strength of molecular bonding forces connecting the polymer matrix and surrounding fluids. The basis for diagnostic imaging is that disease processes alter molecular-scale bonding in ways that vary the measurable stiffness and viscosity of the tissues. This paper reviews linear viscoelastic theory as applied to gelatin hydrogels for the purpose of formulating approaches to molecular-scale interpretation of elasticity imaging in soft biological tissues. Comparing measurements acquired under different geometries, we investigate the limitations of viscoelastic parameters acquired under various imaging conditions. Quasi-static (step-and-hold and low-frequency harmonic) stimuli applied to gels during creep and stress relaxation experiments in confined and unconfined geometries reveal continuous, bimodal distributions of respondance times. Within the linear range of responses, gelatin will behave more like a solid or fluid depending on the stimulus magnitude. Gelatin can be described statistically from a few parameters of low-order rheological models that form the basis of viscoelastic imaging. Unbiased estimates of imaging parameters are obtained only if creep data are acquired for greater than twice the highest retardance time constant and any steady-state viscous response has been eliminated. Elastic strain and retardance time images are found to provide the best combination of contrast and signal strength in gelatin. Retardance times indicate average behavior of fastfluid flows and slowmatrix restructuring in response to the mechanical stimulus. Insofar as gelatin mimics other polymers, such as soft biological tissues, elasticity imaging can provide unique insights into complex structural and biochemical features of connectives tissues affected by disease.