Multi-excitation magnetoacoustic imaging of tissue conductivities

描述(申请人提供)：乳腺癌是美国女性中最危险的肿瘤之一。有相当多的证据表明，乳腺癌的早期诊断和治疗可以显著提高生存机会。虽然X射线乳房摄影是目前的标准筛查技术，但它受到软组织分化差和辐射暴露的限制。钼靶检查阳性的患者需要活检才能确诊，据报道，在很大一部分患者中，钼靶筛查确定的乳腺病变的活检结果为恶性肿瘤阴性。我们建议开发一种新型的、经济的、非电离的、高分辨率和高特异度的电导成像系统，将生物磁学和超声(磁声断层扫描结合磁感应)结合起来，用于乳腺癌的筛查和早期检测。这一发展是基于实验证据，即癌组织表现出明显高于正常组织和良性组织的电导值。在这个R21项目中，我们计划探索和开发一种三维(3D)多激励MAT-MI(meMAT-MI)系统，并在计算机模拟、体模实验和乳房标本成像中对其进行评估，目的是实现整个体积的高分辨率、高特异度的电阻抗成像，并实现具有成本效益的系统实现。在所提出的3DmeMAT-MI中，物体位于静态磁场和时变脉冲磁场中。将对物体施加多个脉冲磁刺激，从而在物体中感应涡流分布。因此，基于感应电流和外加磁场的相互作用，样品将通过洛伦兹力发出声波。在多次激励期间采集物体周围的声信号，以重建与物体中的电导率分布相关的图像。通过利用磁能的多次激发，我们建议重建整个物体体积的完整电导率剖面。我们将开发和优化新型3D meMAT-MI系统，并在计算机模拟和体模实验中评估其可行性。我们还将直接测试其在人类乳腺标本中对乳腺肿瘤进行成像的性能。电阻抗分布的高分辨率成像对于生物医学研究和临床诊断中的各种应用具有重要意义，例如早期癌症检测。高分辨率、非电离、高性价比的电阻抗成像系统的研制成功，将对乳腺癌的筛查和早期发现产生重大影响。

DESCRIPTION (provided by applicant): Breast cancer is one of the most life-threatening tumors among women in U.S. There is considerable evidence that early diagnosis and treatment of breast cancer can significantly increase chances of survival. While X-ray mammography is the current standard screening technique, it is limited by its poor soft tissue differentiation and radiation exposure. Patients with positive mammographic findings require a biopsy for definitive diagnosis, and it was reported that biopsies of breast lesions identified in mammography screenings are negative for malignancy in a significant portion of the patients. We propose to develop a novel, cost-effective, non-ionizing, high resolution, and high specificity imaging system for imaging electrical conductivity by integrating biomagnetism with ultrasound (magnetoacoustic tomography with magnetic induction: MAT-MI) for screening and early detection of breast cancer. This proposed development is based on the experimental evidence that cancerous tissue shows significantly higher electrical conductivity value than normal and benign tissue. In this R21 project, we propose to explore and develop a 3-dimensional (3D) multi-excitation MAT-MI (meMAT-MI) system and evaluate it in computer simulations, phantom experiments, and breast specimen imaging, for the purpose of achieving high resolution, high specificity electrical impedance imaging throughout the volume with a cost effective system realization for breast cancer detection. In the proposed 3D meMAT-MI, the object is located in a static magnetic field and a time-varying pulsed magnetic field. Multiple pulsed magnetic stimulations will be applied to the object, which induce eddy current distributions in the object. Consequently, the sample will emit acoustic waves by the Lorentz force based on the interplay of induced currents and applied magnetic fields. The acoustic signals are collected around the object during multi-excitation to reconstruct images related with the electrical conductivity distribution in the object. Through multi-excitation using magnetic energy, we propose to reconstruct the complete electrical conductivity profiles throughout the volume of the object. We will develop and optimize the novel 3D meMAT-MI system, and assess its feasibility in computer simulations and phantom experiments. We will also test directly its performance in imaging breast tumors in human breast specimens. High resolution imaging of electrical impedance distribution is of significance for a variety of applications in biomedical research and clinical diagnosis, such as early cancer detection. The successful development of a high-resolution, non-ionizing, cost-effective electrical impedance imaging system will have a significant impact to screening and early detection of breast cancer.