The detection of early-stage tumors in the breast by microwave imaging is challenged by both the moderate endogenous dielectric contrast between healthy and malignant glandular tissues and the spatial resolution available from illumination at microwave frequencies. The high endogenous dielectric contrast between adipose and fibroglandular tissue structures increases the difficulty of tumor detection due to the high dynamic range of the contrast function to be imaged and the low level of signal scattered from a tumor relative to the clutter scattered by normal tissue structures. Microwave inverse scattering techniques, used to estimate the complete spatial profile of the dielectric properties within the breast, have the potential to reconstruct both normal and cancerous tissue structures. However, the ill-posedness of the associated inverse problem often limits the frequency of microwave illumination to the UHF band within which early-stage cancers have sub-wavelength dimensions. In this computational study, we examine the reconstruction of small, compact tumors in three-dimensional numerical breast phantoms by a multiple-frequency inverse scattering solution. Computer models are also employed to investigate the use of exogenous contrast agents for enhancing tumor detection. Simulated array measurements are acquired before and after the introduction of the assumed contrast effects for two specific agents currently under consideration for breast imaging: microbubbles and carbon nanotubes. Differential images of the applied contrast demonstrate the potential of the approach for detecting the preferential uptake of contrast agents by malignant tissues.

中文翻译：

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乳腺肿瘤的对比增强微波成像：使用 3D 逼真数值模型的计算研究

通过微波成像检测乳房中的早期肿瘤受到健康和恶性腺体组织之间中等内源性介电对比度和微波频率照射可用的空间分辨率的挑战。脂肪和纤维腺体组织结构之间的高内源性介电对比度增加了肿瘤检测的难度，因为要成像的对比度函数的动态范围高，并且相对于正常组织结构散射的杂波，从肿瘤散射的信号水平较低。微波逆散射技术用于估计乳房内介电特性的完整空间分布，具有重建正常和癌变组织结构的潜力。然而，相关逆问题的不适定性通常将微波照射的频率限制在 UHF 波段，在该波段中早期癌症具有亚波长维度。在这项计算研究中，我们通过多频逆散射解决方案检查三维数值乳房模型中小而紧凑的肿瘤的重建。计算机模型也被用来研究使用外源性造影剂来增强肿瘤检测。目前正在考虑用于乳房成像的两种特定试剂：微泡和碳纳米管，在引入假定的对比度效应之前和之后获得模拟阵列测量值。