Magnetic Resonance Electrical Properties Tomography

描述（由申请人提供）：由于高场MRI有望改善信噪比、提高空间分辨率和使用血氧水平依赖性对比度提高功能成像的灵敏度，因此高场MRI受到越来越多的关注和潜在的广泛临床应用。然而，热效应升高（由于组织加热伴随主磁场强度增加）在高场MRI应用中造成了重大安全问题。比吸收率（SAR）与射频（RF）致热直接相关。在当前高场MRI RF功率传输中，由于缺乏受试者特定基础上的局部SAR值量化，导致了最差情况下的安全限值，这可能会损害与高场相关的潜在改善信噪比和图像对比度。因此，迫切需要实时和受试者特定的电特性成像，用于高场MRI应用中的SAR量化和随后的组织加热管理。该R21探索性项目的目标是探索和开发一种新型磁共振电特性断层扫描（MR-EPT）技术，用于定量预测和主动管理高场MRI应用中的组织加热。为了实现这一目标，我们将致力于以下具体目标：目标1）MR电特性断层扫描方法的发展。目的2）磁共振电特性成像方法及发热定量的实验评价。我们将开发新的理论和算法的电性能成像和局部SAR量化。我们将进行一系列的计算机模拟，并进行良好的控制体模实验和实验，在死后的动物组织，以评估所提出的MR-EPT方法的性能。电特性分布的非侵入性成像对于生物医学研究和临床应用中的各种应用具有重要意义。所提出的MR-EPT方法的成功开发有望提供高分辨率非侵入性电特性成像模式，使得能够在高场MRI中对组织加热进行实时和受试者特异性量化，并促进各种应用，包括 良性与恶性肿瘤特征和功能性脑成像。

DESCRIPTION (provided by applicant): High field MRI has been pursued with increasing interest and potential wide clinical applications due to its promise of improved signal-to-noise ratio, higher spatial resolution, and increased sensitivity for functional imaging using the blood oxygenation level-dependent contrast. However, the elevated thermal effect (due to tissue heating accompanied with an increased main magnetic field strength) poses a major safety concern in high field MRI applications. The Specific Absorption Rate (SAR) is directly related to radio frequency (RF) induced heating. An absence of quantification of the local SAR values on a subject specific basis yields a worse-case safety limit in current high field MRI RF power transmission, which may compromise the underlying improved signal-to-noise ratio and image contrast associated with high field. Therefore, there is a crucial need for real-time and subject-specific electrical property imaging, for the purpose of SAR quantification and subsequent tissue heating management in high field MRI applications. The goal of this R21 exploratory project is to explore and develop a novel magnetic resonance electrical property tomography (MR-EPT) technique for the quantitative prediction and proactive management of tissue heating in high-field MRI applications. To achieve this goal, we will address the following specific aims: Aim 1) Development of MR electrical property tomography methods. Aim 2) Experimental evaluation of MR electrical property tomography methods and heating quantification. We will develop novel theories and algorithms for electrical property imaging and local SAR quantification. We will conduct a series of computer simulations, and perform well controlled phantom experiments and experiments in post-mortem animal tissues to evaluate the performance of the proposed MR- EPT approach. Noninvasive imaging of the electrical property distribution is of significance for a variety of applications in biomedical research and clinical applications. The successful development of the proposed MR- EPT approach promises to provide a high-resolution noninvasive electrical property imaging modality, enabling the real-time and subject-specific quantification of tissue heating in high field MRI, and facilitating various applications including benign versus malignant tumor characterization and functional brain imaging.