Magnetic Resonance Electrical Properties Tomography

描述(申请人提供)：高场磁共振成像因其具有更高的信噪比、更高的空间分辨率和更高的灵敏度而受到越来越多的关注和潜在的广泛临床应用，使用与血氧水平相关的对比度进行功能成像。然而，热效应(由于组织加热伴随着主磁场强度的增加)在高场磁共振应用中构成了一个主要的安全问题。比吸收率(SAR)与射频(RF)加热直接相关。缺乏对特定对象的局部SAR值的量化会在当前高场MRI射频功率传输中产生更糟糕的安全限制，这可能会损害与高场相关的潜在改善的信噪比和图像对比度。因此，在高场MRI应用中，为了进行SAR量化和随后的组织加热管理，迫切需要针对特定对象的实时电特性成像。该R21探索性项目的目标是探索和开发一种新的磁共振电特性层析成像(MR-EPT)技术，用于在高场磁共振应用中对组织加热进行定量预测和主动管理。为了实现这一目标，我们将致力于以下具体目标：目标1)发展磁共振电特性层析成像方法。目的2)磁共振电性层析成像方法及加热量化的实验评价。我们将为电特性成像和局部SAR量化开发新的理论和算法。我们将进行一系列计算机模拟，并进行良好控制的体模实验和死后动物组织的实验，以评估所提出的MR-EPT方法的性能。电学性质分布的非侵入性成像在生物医学研究和临床应用中具有重要意义。所提出的MR-EPT方法的成功开发有望提供一种高分辨率的非侵入性电特性成像方式，使高场MRI中组织加热的实时和特定于对象的量化成为可能，并促进各种应用，包括 良性肿瘤与恶性肿瘤的特征和脑功能成像。

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.