RF Interface System and Coil for Multi-Nuclear Lung MR Imaging at 3T

描述(由申请人提供)：肺的超极化氦和氙气磁共振成像已被证明提供了关于肺功能的有用的生理信息。超极化氦成像已被证明可以提供出色的肺气体空间成像，同时允许结构-功能信息，如肺泡大小和氧气消耗。超极化的氙气通过肺实质溶解在血池中，为同时进行通风、灌注成像和气体交换测量提供了可能。此外，对惰性氟化气体(如SF6)的成像显示了肺部成像的巨大前景。虽然已经做了很多工作来表征气体成像的用途，但该领域仍然处于研究阶段，部分原因是缺乏可用的临床射频技术来进行多核扫描。在这里，我们建议创建一个射频线圈和接口平台，可以永久调谐到上述任何特定频率。此外，这项技术将专门为3T磁铁创造，越来越多的医院正在购买和安装这种磁场强度。这种线圈和接口设计将由临床磁共振解决方案公司的Ralph Hashoian开发，他之前曾为气体成像设计和交付线圈，并将由马萨诸塞大学医学院的Mitchell Albert验证和测试，后者是活体超极化气体成像的共同发明者。我们的线圈设计将由一个具有四个环路元件的发射/接收正交型柔性线圈组成。这种设计将同时考虑到患者的舒适性和具有高信噪比的同质传输。我们在1.5T的超极化氦成像中使用这种线圈设计的初步结果产生了很好的结果。线圈接口将由一个低损耗、高功率发射接收开关、低噪声前置放大器和一个正交混合器组成，所有这些都集成到一个注塑外壳中，该外壳将插入主系统线圈连接。包括线圈ID、故障分析和PIN二极管驱动器所需的特定OEM电路。这种集成的接口方法将使研究中涉及的所有气体频率的线圈连接更容易，并确保简单、坚固和临床相关的接口。最后，我们的射频线圈设计和接口平台将旨在克服3T面临的挑战，包括高射频功率沉积、患者阻抗匹配损耗增加以及患者安全问题。一旦开发完成，我们将通过获取超极化氦通风和呼吸道图像来测试我们的设计。这些图像将由放射科医生对图像质量和均质性进行评估。总而言之，我们的设计将为研究社区提供更有效的临床射频线圈和接口，并最终加快向临床的过渡。 公共卫生相关性：超极化气体和惰性氟化气体磁共振成像站在临床应用的门口。然而，由于缺乏可用的多核射频技术来进行这些检查，它们在临床上的进展受到了阻碍。在这里，我们提出了一种射频线圈设计和扫描仪接口，它无缝地集成到临床扫描仪中，以成像3T下的超极化氦、氙气或惰性氟化气体。这种设计的目标是临床合规性，将允许高信噪比成像，同时保持患者的舒适性和安全性。综上所述，拟议的集成线圈和接口的架构将促进临床气体肺成像，并最终有助于促进该技术的临床接受和翻译研究。

DESCRIPTION (provided by applicant): Hyperpolarized helium and xenon MRI of the lungs has been shown to provide useful physiological information about pulmonary function. Hyperpolarized helium imaging has been shown to provide outstanding imaging of lung gas spaces while allowing for structure-function information such as alveolar dimensions and oxygen depletion. Hyperpolarized xenon dissolves in the blood pool through lung parenchyma, opening up the potential for simultaneous ventilation and perfusion imaging and gas exchange measurements. Further, imaging of inert fluorinated gases such as SF6 show great promise for pulmonary imaging. While much work has been performed to characterize the utility of gas imaging, the field still remains in the research phase, partially due to the lack of available clinical RF technology for multinuclear scanning. Here, we propose to create an RF coil and interface platform that can be permanently tuned to any of the aforementioned specific frequencies. Further, this technology will be specifically created for 3T magnets, a field strength that more and more hospitals are purchasing and installing. This coil and interface design will be developed by Ralph Hashoian at Clinical MR Solutions, who has previously designed and delivered coils for gas imaging, and it will be validated and tested by Mitchell Albert at the University of Massachusetts Medical School, a co-inventor of in vivo hyperpolarized gas imaging. Our coil design will consist of a transmit/receive quadature flexible coil with four loop elements. This design will simultaneously allow for patient comfort and homogenous transmission with high signal to noise reception. Our preliminary results at 1.5T using this type of coil design in hyperpolarized helium imaging have produced excellent results. The coil interface will consist of a low loss, high power transmit receive switch, low noise pre-amplifiers, and a Quadrature hybrid, all integrated into an injection molded enclosure that will plug into the main system coil connection. Included will be specific OEM required circuits for coil ID, fault analysis and PIN diode drivers. This integrated interface approach will allow for easier coil connections for all the gas frequencies involved in the study and ensure a simple, robust and clinically relevant interface. Finally, our RF coil design and interface platform will be designed to overcome the challenges at 3T including high RF power deposition, increased patient impedance matching loss, and patient safety concerns. Once developed, we will test our design by acquiring hyperpolarized helium ventilation and airway images. These images will be evaluated by a radiologist for image quality and homogeneity. Taken together, our design will offer more clinically effective RF coils and interface to the research community and ultimately hasten the transition to the clinic. PUBLIC HEALTH RELEVANCE: Hyperpolarized gas and inert fluorinated gas MR imaging stand at the doorstep of clinical application. However, their advancement to the clinic is hindered by the lack of available multinuclear RF technology to perform these exams. Here, we propose an RF coil design and scanner interface that is seamlessly integrated into the clinical scanner to image hyperpolarized helium, xenon, or inert fluorinated gases at 3T. This design, which is targeted for clinical compliance, will allow for high signal to noise imaging while maintaining patient comfort and safety. Taken together, the proposed architecture of an integrated coil and interface will facilitate clinical gas lung imaging and ultimately help facilitate clinical acceptance and translational research of the technique.