论文标题

软组织粘弹性特性的超声估计

Ultrasonic Estimation of Soft Tissue Visco Elastic Properties

论文作者

Ahmed, Hassan M.

论文摘要

诊断超声的常规成像被广泛使用。尽管它使软组织回声的差异显而易见且清晰,但它在描述和估计软组织机械性能方面却未能进行。它无法描绘它们的机械性能,例如弹性和刚度。估计机械性能增加了病变鉴定或任何病理变化的机会。医师现在正在将组织的机械特性描述为诊断指标。通过在组织上施加声辐射力脉冲(ARFI)并计算所得的剪切波速度来实现组织的机械性能。由于难以精确地计算组织内部的剪切波速度,因此通过以非常高的框架速率分析组织的超声图像来估计。在这项研究中,使用有限元分析估算剪切波速度。构建了二维模型,以模拟组织的机械性能。对于广义的软组织模型,使用琼脂明质模型,因为它具有与软组织相似的特性。在提议模型的中心施加了点力。由于这种力,引起了变形。沿模型的横向尺寸跟踪峰位移,以估算使用时间峰位移(TTP)方法的传播波的剪切波速度。

Conventional imaging of diagnostic ultrasound is widely used. Although it makes the differences in the soft tissues echogenicities' apparent and clear, it fails in describing and estimating the soft tissue mechanical properties. It cannot portray their mechanical properties, such as the elasticity and stiffness. Estimating the mechanical properties increases chances of the identification of lesions or any pathological changes. Physicians are now characterizing the tissue's mechanical properties as diagnostic metrics. Estimating the tissue's mechanical properties is achieved by applying an Acoustic Radiation Force Impulse (ARFI) on the tissue and calculating the resulted shear wave speed. Due to the difficulty of calculating the shear wave speed precisely inside the tissue, it is estimated by analyzing ultrasound images of the tissue at a very high frame rate. In this study, the shear wave speed is estimated using finite element analysis. A two-dimensional model is constructed to simulate the tissue's mechanical properties. For a generalized soft tissue model, Agar-gelatine model is used because it has similar properties to the soft tissue. A point force is applied at the center of the proposed model. As a result of this force, a deformation is caused. Peak displacements are tracked along the lateral dimension of the model to estimate the shear wave speed of the propagating wave using the Time-To-Peak displacement (TTP) method.

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