Zhai Liang, Palmeri Mark L, Bouchard Richard R, Nightingale Roger W, Nightingale Kathryn R
Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
Ultrason Imaging. 2008 Apr;30(2):95-111. doi: 10.1177/016173460803000203.
The goal of this work is to develop and characterize an integrated indenter-ARFI (acoustic radiation force impulse) imaging system. This system is capable of acquiring matched datasets of ARFI images and stiffness profiles from ex vivo tissue samples, which will facilitate correlation of ARFI images of tissue samples with independently-characterized material properties. For large and homogeneous samples, the indenter can be used to measure the Young's moduli by using Boussinesq's solution for a load on the surface ofa semi-infinite isotropic elastic medium. Experiments and finite element method (FEM) models were designed to determine the maximum indentation depth and minimum sample size for accurate modulus reconstruction using this solution. Applying these findings, indentation measurements were performed on three calibrated commercial tissue-mimicking phantoms and the results were in good agreement with the calibrated stiffness. For heterogeneous tissue samples, indentation can be used independently to characterize relative stiffness variation across the sample surface, which can then be used to validate the stiffness variation in registered ARFI images. Tests were performed on heterogeneous phantoms and freshly-excised colon cancer specimens to detect the relative stiffness and lesion sizes using the combined system. Normalized displacement curves across the lesion surface were calculated and compared. Good agreement ofthe lesion profiles was observed between indentation and ARFI imaging.
这项工作的目标是开发并表征一种集成式压头-ARFI（声辐射力脉冲）成像系统。该系统能够从离体组织样本中获取ARFI图像和硬度剖面的匹配数据集，这将有助于将组织样本的ARFI图像与独立表征的材料特性进行关联。对于大尺寸且均匀的样本，可使用布辛涅斯克（Boussinesq）关于半无限各向同性弹性介质表面载荷的解，通过压头来测量杨氏模量。设计了实验和有限元方法（FEM）模型，以确定使用该解进行精确模量重建时的最大压痕深度和最小样本尺寸。应用这些发现，对三种校准过的商用仿组织体模进行了压痕测量，结果与校准后的硬度吻合良好。对于异质组织样本，压痕可独立用于表征样本表面的相对硬度变化，进而用于验证配准后的ARFI图像中的硬度变化。使用该组合系统对异质体模和新鲜切除的结肠癌标本进行了测试，以检测相对硬度和病变大小。计算并比较了病变表面的归一化位移曲线。在压痕和ARFI成像之间观察到病变轮廓有良好的一致性。
