权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

RF coils based on low-profile electromagnetic band gap (EBG)-structures for the usage in magnetic resonance imaging (MRI)

基于薄型电磁带隙 (EBG) 结构的射频线圈，用于磁共振成像 (MRI)

基本信息

批准号：
191947714
负责人：
Professor Dr. Harald Quick
金额：
--
依托单位：
Fachgebiet Allgemeine und Theoretische Elektrotechnik (ATE)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/191947714?language=en
关键词：
RF coils based low profile

项目摘要

During the first period of this DFG project novel multi-channel radio frequency coils for 7Tesla MRI have been proposed and were positively evaluated using a near-field measurement system. Each element comprises of a meandered dipole with an electrical length of approximately three half wave lengths and a shielding plate behind it in order to primarily generate the magnetic field in the direction of the patient (transmit case) or primarily receive from there. The shielding is either a length optimized metallic plate or a flat electromagnetic bandgap structure forming a high impedance surface (HIS). In the former case, the eigen-resonant base plate results in improved electro-magnetic fields in the body of the patient. The HIS shield on the other hand enforces in-phase mirror-currents that lead to an improved B1 efficiency (magnetic field amplitude per accepted power). Furthermore adjacent coil elements are more isolated from each other due to the band-gap characteristic of the structured meta-surface. In the second phase of the DFG project, the available coils are to be tested extensively on a 7-Tesla scanner. Initially, this evaluation includes single elements, which are tested by utilizing so-called phantoms that mimic the human body in its electromagnetic properties. Subsequently, more complex multi-element coil-systems will be established (4-channel setups for knee or head imaging and 8-channel arrays for the abdominal and back imaging). Finally, in-vivo measurements of the above mentioned body parts shall be carried out with the innovative multi-channel coils of this project. Parallel to the tests with the 7-Tesla scanner further research shall be carried out following the previous innovative RF coil approaches, also based on the findings related to the practical evaluation. We would like to explore a location-dependent surface impedance of the shield. Initially the extreme cases PEC (homogeneous metal) and PMC (structured HIS meta-surface) will be considered. This concept represents a further unexplored degree of freedom in the generation of MRI-optimized electromagnetic fields in the human body. In addition to the above-mentioned dipole elements ring antennas (magnetic dipoles) will be considered above HIS shields, and applied especially in parts of the body, where such a ring topology offers advantages, such as for breast imaging. Finally, combinations of electric and magnetic dipoles will be examined, i.e., the established meander dipoles are combined with ring antennas, so that both, tangential and normal magnetic field components are generated. A correct phasing of these two components results in a single element that produces a circularly polarized magnetic near field.

在该DFG项目的第一阶段，提出了用于7特斯拉MRI的新型多通道射频线圈，并使用近场测量系统进行了积极评价。每个元件包括一个电长度约为三个半波长的曲折偶极和其后面的屏蔽板，以便主要在患者方向上产生磁场（发射外壳）或主要从那里接收。屏蔽是长度优化的金属板或形成高阻抗表面（HIS）的平坦电磁带隙结构。在前一种情况下，本征谐振基板导致患者体内的电磁场得到改善。另一方面，HIS屏蔽体强制执行同相镜像电流，从而提高B1效率（每接受功率的磁场幅度）。此外，由于结构化元表面的带隙特性，相邻线圈元件彼此更加隔离。在DFG项目的第二阶段，将在7特斯拉扫描仪上对可用线圈进行广泛测试。最初，该评估包括单个元素，这些元素通过利用所谓的模拟人体电磁特性的幻影进行测试。随后，将建立更复杂的多元件线圈系统（用于膝盖或头部成像的4通道设置和用于腹部和背部成像的8通道阵列）。最后，应使用本项目的创新多通道线圈对上述身体部位进行体内测量。在使用7 T扫描仪进行测试的同时，还应根据与实际评价相关的发现，按照先前的创新射频线圈方法进行进一步研究。我们想探讨一个位置相关的屏蔽表面阻抗。最初将考虑极端情况PEC（均质金属）和PMC（结构化HIS元表面）。该概念代表了在人体中生成MRI优化电磁场的进一步未探索的自由度。除了上述偶极元件之外，环形天线（磁偶极）将被考虑在HIS屏蔽之上，并且特别地应用于身体的部分，其中这种环形拓扑提供了优点，诸如用于乳房成像。最后，将检查电偶极子和磁偶极子的组合，即，所建立的弯折偶极子与环形天线相结合，从而产生切向和法向磁场分量。这两个分量的正确定相导致产生圆偏振磁近场的单个元件。