Microwave-induced thermoacoustic imaging (MI-TAI) remains one of the focus of attention among biomedical imaging modalities over the last decade. However, the transmission and distribution of microwave inside bio-tissues are complicated, thus result in severe artifacts. In this study, to reveal the underlying mechanisms of artifacts, we deeply investigate the distribution of specific absorption rate (SAR) inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments. Our simulated results, which are confirmed by the associated experimental results, show that the SAR distribution highly depends on the geometries of the imaging targets and the polarizing features of the microwave. In addition, we propose the potential mechanisms including Mie-scattering, Fabry-Perot-feature, small curvature effect to interpret the diffraction effect in different scenarios, which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.

中文翻译：

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通过在热声成像中映射 SAR 来研究伪影

微波诱导的热声成像 (MI-TAI) 仍然是过去十年生物医学成像模式中关注的焦点之一。然而，微波在生物组织内的传输和分布是复杂的，从而导致严重的伪影。在这项研究中，为了揭示伪影的潜在机制，我们使用数学模拟和相应的实验深入研究了具有不同形态特征的组织模拟体模内部的比吸收率 (SAR) 分布。我们的模拟结果得到了相关实验结果的证实，表明 SAR 分布高度依赖于成像目标的几何形状和微波的偏振特征。此外，我们提出了包括米氏散射、法布里-珀罗特征、