Three-dimensional microwave imaging of realistic numerical breast phantoms via a multiple-frequency inverse scattering technique
Three-dimensional microwave imaging of realistic numerical breast phantoms via a multiple-frequency inverse scattering technique
复制标题
DOI：
10.1118/1.3443569
复制
发表时间：
2010-08-01
期刊：
影响因子：
3.8
通讯作者：
Van Veen, Barry D.
中科院分区：
文献类型：
--
作者：
Shea, Jacob D.;Kosmas, Panagiotis;Van Veen, Barry D.
目的：乳腺密度测量有可能在个体化乳腺癌风险评估和预防决策中发挥重要作用。乳腺密度的常规评估需要一种低成本、非电离、三维 (3-D) 断层扫描成像模式，该模式利用致密纤维腺组织和密度较低的脂肪组织之间的强烈特性对比。这项计算研究的目的是研究使用低功率微波的 3D 断层扫描的性能，以重建乳房组织介电特性的空间分布，并评估应用于乳房密度表征的模式。方法：采用在结构和介电特性方面均真实的最先进的 3D 数字乳房模型。测试模型包括来自四类乳房 X 线摄影乳房密度的每一类的一个样本。由于这些模型的特性是已知的，因此这些测试台可以作为成像结果的严格基准。畸变玻恩迭代成像方法应用于数值体模的模拟阵列测量。成像算法中的正向求解器采用时域有限差分法求解时域麦克斯韦方程组，并使用亥姆霍兹波动方程的积分方程形式估计介电分布。实现了多频率、边界约束、矢量场逆散射解决方案，可以实现大规模 3-D 问题的实际反演。利用微波频率下乳房组织的频率相关特性的知识来获得乳房内部的色散介电分布的参数化重建。成像是在高分辨率体素的基础上进行的，并且解决方案受到组成乳腺组织的已知介电特性范围的限制。该成像方法使用乳房模型进行验证，该模型在均匀的内部具有单个高对比度内部散射目标。然后使用该方法对一组不同纤维腺体组织密度的真实数字乳房模型进行成像。结果：给出了每个数字模型的成像结果，并显示了该方法相对于组织密度的稳健性。在每种情况下，纤维腺组织的分布在所得图像中得到很好的体现。所用频率下图像的分辨率比正常组织结构的特征尺寸更宽，导致其重建出现模糊。结论：本研究的结果支持 3D 微波断层扫描用于对乳房中正常组织的分布进行成像的实用性，特别是致密的纤维腺组织与密度较低的脂肪组织，并建议进一步研究其在乳房体积评估中的用途 乳房密度是有保证的。 (C) 2010 年美国医学物理学家协会。 [DOI：10.1118/1.3443569]
Purpose: Breast density measurement has the potential to play an important role in individualized breast cancer risk assessment and prevention decisions. Routine evaluation of breast density will require the availability of a low-cost, nonionizing, three-dimensional (3-D) tomographic imaging modality that exploits a strong properties contrast between dense fibroglandular tissue and less dense adipose tissue. The purpose of this computational study is to investigate the performance of 3-D tomography using low-power microwaves to reconstruct the spatial distribution of breast tissue dielectric properties and to evaluate the modality for application to breast density characterization.Methods: State-of-the-art 3-D numerical breast phantoms that are realistic in both structural and dielectric properties are employed. The test phantoms include one sample from each of four classes of mammographic breast density. Since the properties of these phantoms are known exactly, these testbeds serve as a rigorous benchmark for the imaging results. The distorted Born iterative imaging method is applied to simulated array measurements of the numerical phantoms. The forward solver in the imaging algorithm employs the finite-difference time-domain method of solving the time-domain Maxwell's equations, and the dielectric profiles are estimated using an integral equation form of the Helmholtz wave equation. A multiple-frequency, bound-constrained, vector field inverse scattering solution is implemented that enables practical inversion of the large-scale 3-D problem. Knowledge of the frequency-dependent characteristic of breast tissues at microwave frequencies is exploited to obtain a parametric reconstruction of the dispersive dielectric profile of the interior of the breast. Imaging is performed on a high-resolution voxel basis and the solution is bounded by a known range of dielectric properties of the constituent breast tissues. The imaging method is validated using a breast phantom with a single, high-contrast interior scattering target in an otherwise homogeneous interior. The method is then used to image a set of realistic numerical breast phantoms of varied fibroglandular tissue density.Results: Imaging results are presented for each numerical phantom and show robustness of the method relative to tissue density. In each case, the distribution of fibroglandular tissues is well represented in the resulting images. The resolution of the images at the frequencies employed is wider than the feature dimensions of the normal tissue structures, resulting in a smearing of their reconstruction.Conclusions: The results of this study support the utility of 3-D microwave tomography for imaging the distribution of normal tissues in the breast, specifically, dense fibroglandular tissue versus less dense adipose tissue, and suggest that further investigation of its use for volumetric evaluation of breast density is warranted. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3443569]