Schmidt Rita, Webb Andrew
IEEE Trans Biomed Eng. 2016 Nov;63(11):2390-2395. doi: 10.1109/TBME.2016.2533659. Epub 2016 Feb 23.
To design and characterize a new set-up for dual nuclei MRI combining an annular dielectric resonator filled with high permittivity material for phosphorous (P) and a traveling wave antenna for proton imaging.
Recent studies have shown that an annular cylinder filled with water can serve as dielectric resonator for proton MRI of the extremities at 7 T. Using a very high permittivity material such as BaTiO, this type of dielectric resonator can potentially be designed for lower gyromagnetic ratio nuclei. Combining this with a remote antenna for proton imaging, an alternative method for dual frequency imaging at ultrahigh field has been implemented.
3D electromagnetic simulations were performed to examine the efficiency of the dielectric resonator. The new dielectric resonator was constructed for P acquisition at 121 MHz on a human 7 T MRI system. Phantom and in vivo scans demonstrated the feasibility of the setup, although the current sensitivity of the dielectric resonator is only half that of an equivalently sized birdcage.
The new approach offers a simple implementation for dual nuclei imaging at ultrahigh field, with several possibilities for further increases in sensitivity.
Utilizing high permittivity materials enables very simple designs for high field RF coils: in the current configuration the interactions between the proton and phosphorous resonators are very low.
设计并表征一种用于双原子核磁共振成像（MRI）的新装置，该装置结合了一个填充高介电常数材料用于磷（P）成像的环形介质谐振器和一个用于质子成像的行波天线。
最近的研究表明，一个装满水的环形圆柱体可以作为7T时四肢质子MRI的介质谐振器。使用诸如钛酸钡这种非常高介电常数的材料，这种类型的介质谐振器有可能被设计用于较低旋磁比的原子核。将其与用于质子成像的远程天线相结合，实现了一种在超高场进行双频成像的替代方法。
进行了三维电磁模拟以检验介质谐振器的效率。在一台人体7T MRI系统上构建了用于在121MHz采集磷信号的新型介质谐振器。体模和活体扫描证明了该装置的可行性，尽管目前介质谐振器的灵敏度仅为同等尺寸鸟笼式线圈的一半。
这种新方法为超高场双原子核成像提供了一种简单的实现方式，并且有进一步提高灵敏度的多种可能性。
利用高介电常数材料能够实现非常简单的高场射频线圈设计：在当前配置中，质子和磷谐振器之间的相互作用非常低。
