磁共振射频接收与局部匀场一体化线圈关键问题研究

In magnetic resonance imaging (MRI), the accurate diagnosis for brain functional diseases is confronted with the problems of signal loss and image artifacts, which are caused by the non-uniform magnetic field produced by the various magnetic susceptibility of different tissues in human brain. Combining RF coils with local B0-shim coils is an important approach to solve the above problems. However, there are some problems in performance analysis and structure design. Moreover, the shimming mechanism and the influence mechanism between the RF coil array and the B0-shim coil array are not clear. In this study, the analysis method and performance evaluation, the decoupling method and structure optimized design of the integrated RF and B0-shim coil array will be investigated. Based on the preliminary studies, the simulation method and performance evaluation will be achieved by improving the electromagnetic field numerical calculation method and the gradient multi-echo imaging method. Based on the analysis method, the shimming mechanism will be investigated. The coupling between coil elements will be removed or decreased by the induced current elimination method on the basis of the influence mechanism of the integrated RF and B0-shim coil array. The performance optimization strategy of the integrated RF and B0-shim coil array will be also given. Based on the clinical application, an integrated RF and B0-shim coil array will be developed. The successful implementation of this project will provide new theory basis and technology foundation for MRI, and promote the wide application of MRI in clinic.

在磁共振成像中，由于人脑组织磁化率差异引起非均匀性磁场，导致信号丢失和图像伪影，是脑功能性疾病精准诊疗面临的关键问题。在射频接收线圈中增加局部匀场线圈是解决上述问题的重要途径。目前射频接收与局部匀场一体化线圈在性能分析和结构设计等方面存在不完善，而且匀场机理以及局部匀场线圈对射频接收线圈影响机制的阐明也有待完善。本项目主要研究一体化线圈性能分析与评估方法、完善去耦合方法及建立一体化线圈的结构优化设计方法。在前期工作基础上，改进基于电磁场数值计算方法的性能理论分析方法和基于梯度多回波成像的性能实验评估方法，探索一体化线圈的匀场机理；阐明一体化线圈的耦合机制，完善基于感应电流消除原理的去耦合方法；给出一体化线圈的性能最优化策略；并针对于临床应用，开发一套射频接收与局部匀场一体化的原型线圈。本项目的成功实施，将为磁共振成像的发展提供新的理论基础和技术基础，并推动其在临床上的广泛应用。

项目按计划执行，完成了相关的研究目标和预期成果。本项目旨在通过建立射频接收与局部匀场一体化线圈的设计方法以最大限度优化其性能，从而减少磁共振图像磁化率伪影，提高图像质量。建立了一套局部匀场线圈和射频接收线圈的理论与实验分析方法，实现了一体化线圈的性能评估和匀场机理探索；探索了局部匀场线圈对射频接收线圈的影响，实现了局部匀场线圈和射频接收线圈之间的去干扰，射频接收线圈的信噪比损失在5%以内；建立了射频接收与局部匀场一体化线圈的结构优化设计方法，开发了一套3通道射频接收与5通道局部匀场的原型线圈，磁场均匀性提高30%左右，脑功能图像的畸变和伪影大大减少，实现了较好的成像质量。项目预期培养研究生2-3名，申请专利2-4项，发表SCI论文2-3篇。通过本项目的顺利实施，各项指标均达到预期目标，其中培养研究生2名，申请专利15项，发表SCI论文2篇。