超高场磁共振有巨大的临床应用与神经科学研究潜力，但伴随扫描产生的组织发热效应是主要安全隐患。为保障扫描安全，同时发挥超高场磁共振的成像优势，本项目创新性的提出一套工程解决方案：首先开发一种全新的在体电特性定量成像方法，重建空间分布不均匀的组织电特性，并应用于主流的多通道阵列线圈，克服传统算法的不足；然后定量预测组织局部能量沉积（SAR），并依此优化设计射频脉冲序列，实现对局部SAR在安全范围内的精确控制，同时充分且均匀激发磁共振信号、最大化提高成像的信噪比与对比度。当前业界在超高场磁共振射频脉冲序列设计中对SAR值的获取基于大量数值模型仿真结果，不能反映成像个体的特异性；而本项目SAR值的测量来自在体测量与重建，是被试个体真实物理参数和特定实验环境的反映，射频脉冲序列针对被试“量身定做”。拟通过计算机仿真以及水模模型、离体生物组织、死后生物器官的7T磁共振实验定量评估该方案的有效性与可行性

Ultra-high-field (UHF) MRI has great potential in clinical applications as well as in aiding neuroscience studies; however, elevated tissue heating due to RF exposure has been the major safety concern to restrain its wide use. To ensure RF safety and fully exploit the entire range of benefits inherently offered by UHF MRI, a novel approach has been proposed in this study: first we develop a new electrical properties (EPs) tomography method, which takes into account of the inhomogeneous distribution of EPs and applies to multi-channel coil array, therefore overcoming the limitations of existing methods; then, the local SAR is quantitatively estimated, based on which the RF pulse sequence is optimized and designed, so the local SAR is constrained within the safety level, while the MRI signal is fully and homogeneously excited, with the image quality largely enhanced. The current practice in UHF MRI pulse sequence design utilizes local SAR values obtained from numerical simulations, which is a generic yet conservative estimation; whereas in the proposed approach, local SAR is calculated on a subject-specific basis, so the pulse is “tailored” to every subject. A series of numerical evaluations and 7T MRI experiments will be conducted over physical phantoms, biological tissues, and post-mortem animal organs, in order to evaluate the efficacy and feasibility.