胃肠道肿瘤是常见的消化道肿瘤，胃肠道间质瘤（Gastrointestinal stromal tumors, GIST）是胃肠道消化系统中最常见的间叶源性肿瘤，但目前诊断GIST的技术手段存在各自的限制。磁声耦合成像针对生物组织的电特性进行成像，能达到毫米级的空间分辨率，具有重要的研究意义。由于磁声信号微弱，信噪比受到信号衰减、电磁干扰等影响，因此，改善磁声电特性图像质量具有重要意义。本研究针对目前磁感应磁声层析成像技术（Magnetoacoustic Tomography with Magnetic Induction, MAT-MI）信号微弱，图像质量受限制等问题，提出利用液态金属作为造影剂提升MAT-MI成像质量。

镓基液态金属（Liquid Metal, LM）作为一种新型生物医学功能材料受到广泛关注，其在常温下呈液态、具有良好的导电性和流动性，不易挥发，安全无毒，显示出液态金属为一种安全稳定的影像增强剂，在医学电磁成像特别是磁声成像方面重要的应用价值。

本研究对液态金属的特性进行了研究和测试，探索了电场作用下液态金属在不同电解质溶液中的现象，对液态金属在NaOH溶液中的电化学驱动效应和形变特性进行了验证。设计了磁性液态金属的制备过程，并在磁场控制下对磁性液态金属的非接触操控进行了实验。初步验证了液态金属的变形和可操控性能，证明液态金属作为新型的可变形材料可以填充到肠道等复杂管腔组织内进行造影成像的可行性。

在此基础上，本研究建立基于M序列（Maximum length sequence, M sequence）编码激励MAT-MI实验平台，测试了内置液态金属的凝胶仿体成像效果，以及磁性液态金属在磁力控制下在管腔内移动至不同位置的成像对比实验。在仿体实验的基础上，本文对离体小鼠组织进行了实验测试，包括离体鼠肠组织和离体鼠胃组织灌注液态金属造影的成像实验，对比了CT与MAT-MI的成像结果，分析了小鼠胃组织置入液态金属前后成像信噪比，对液态金属作为造影剂对小鼠活体MAT-MI成像质量的提升进行了实验验证。

总之，本研究提出了基于液态金属提高磁声成像质量的方法，并利用MAT-MI重建了液态金属的分布图像。实现对活体小鼠基于磁声成像的液态金属胃部造影，验证了液态金属对MAT-MI信噪比的改善效果。本研究对于提高MAT-MI成像质量，推进液态金属作为造影剂的胃肠肿瘤早期临床诊断打下重要基础。

Gastrointestinal tumors are common malignancies of the digestive tract, with gastrointestinal stromal tumors (GISTs) being the most prevalent mesenchymal tumors within this system. Current diagnostic techniques for GIST, however, present various limitations. Magnetoacoustic tomography (MAT), which focuses on the electrical properties of biological tissues, allows for imaging with millimeter-level spatial resolution and holds significant research value. However, due to weak magnetoacoustic signals, the signal-to-noise ratio (SNR) is affected by signal attenuation and electromagnetic interference. Therefore, improving the image quality of MAT is crucial. This study proposes using liquid metal as a contrast medium to enhance the image quality of Magnetoacoustic Tomography with Magnetic Induction (MAT-MI), addressing the current challenges of weak signals and limited image quality.

As an emerging biomedical functional material, gallium-based liquid metal (LM) has garnered extensive attention due to its liquid state at room temperature, excellent electrical conductivity, fluidity, non-volatility, safety, and non-toxicity. These properties demonstrate the potential of liquid metal as a safe and stable imaging enhancer, particularly in electromagnetic and magnetoacoustic imaging applications.

This research investigates and tests the characteristics of liquid metal, exploring its behavior under electric fields in various electrolyte solutions. The electrochemical driving effect and deformation properties of liquid metal in NaOH solution were verified. A preparation process for magnetic liquid metal was designed, and experiments on non-contact manipulation of magnetic liquid metal under magnetic field control were conducted. Preliminary verification of the deformability and controllability of liquid metal was achieved, demonstrating the feasibility of using liquid metal as a novel deformable material for imaging within complex luminal tissues such as the intestines.

Based on this foundation, an MAT-MI experimental platform based on Maximum Length Sequence (M-sequence) coded excitation was established. Imaging tests were conducted on phantoms containing liquid metal gel, as well as comparative imaging experiments of magnetic liquid metal moving to different positions within luminal structures under magnetic control. Following phantom experiments, ex vivo mouse tissue experiments were performed, including imaging of ex vivo mouse intestine and stomach tissues infused with liquid metal contrast medium. Comparisons between CT and MAT-MI imaging results were made, analyzing the SNR of mouse stomach tissue before and after liquid metal infusion. Experimental validation of the improvement in MAT-MI imaging quality using liquid metal as a contrast medium was conducted on live mice.

In summary, this study proposes a method to enhance magnetoacoustic imaging quality using liquid metal, reconstructing the distribution images of liquid metal with MAT-MI. It successfully achieved liquid metal-based gastric imaging in live mice using magnetoacoustic tomography, confirming the enhancement of MAT-MI SNR by liquid metal. This research lays a significant foundation for improving MAT-MI imaging quality and advancing the use of liquid metal as a contrast medium for early clinical diagnosis of gastrointestinal tumors.