RF-penetrable PET ring for acquiring simultaneous time-of-flight PET and MRI data

 描述（由申请人提供）：我们提议创建和探索一种射频（RF）可穿透正电子发射断层扫描（PET）系统技术，该技术可插入磁共振成像（MRI）系统中，用于同时采集PET/MRI数据。集成PET/MRI已上升到医学成像技术的最前沿，显示出成为疾病表征的强大工具的希望，因为它能够同时测量身体软组织中的分子、功能和解剖信息。由于这一承诺，西门子、通用电气和飞利浦等公司已经开发并提供组合式PET/MR系统。然而，影响该技术长期影响的挑战之一是当前成本（500 - 600万美元），这是由于公司开发集成产品所需的巨额投资，以及用户需要购买PET和MRI子系统。我们的实验室正在通过创建世界上第一个RF可穿透的PET环来解决这些问题，该环原则上可以插入任何现有的MR系统，同时仍然允许使用内置的MR RF发射线圈。这将避免两种模态的昂贵集成，到目前为止，为了实现全身PET/MR，这需要对MR系统进行实质性修改，包括重新设计身体发射线圈子系统以驻留在PET环内。因此，所提出的技术将大大降低现有MR站点升级到PET/MR能力的成本障碍，因为它们将仅需要购买RF透射PET插入物，并且它还将减少实现集成PET/MRI的行业投资。假设：使用所提出的新颖电光信号传输方案，我们可以创建可穿透RF场的PET插入物，并且因此可以使用MR系统的内置体发射线圈实现同时ToF-PET/MR。使PET环插入件能够RF穿透（即，使RF场泄漏到PET环内部）的基本思想是使其相对于MR系统电浮动，并且 在PET探测器模块之间具有小的间隙，其中场线可以泄漏。这种浮动PET环通过“电光”信号传输的概念成为可能，该概念来自电信领域;在我们的配方中，快速闪烁探测器信号耦合到微小的激光器，转换为近红外光，并沿着长的闪烁级光纤传输，从而实现与MR系统的电隔离。此外，由于电光方法使用光纤，因此与使用长电缆的PET系统设计相比，其显著减少了MR系统内的电足迹，同时实现了成像所需的优异的空间、能量和时间分辨率。 彼前在这个项目中，我们将通过一个 脑大小的PET插入物，并在3 T MRI系统中测试其RF transmittance。为了实现这些目标，我们探索了许多创新的概念。

 DESCRIPTION (provided by applicant): We propose to create and explore a radio-frequency (RF)-penetrable positron emission tomography (PET) system technology that can be inserted into a magnetic resonance imaging (MRI) system for acquiring simultaneous PET/MRI data. Integrated PET/MRI has risen to the cutting edge of medical imaging technology, showing promise to be a powerful tool in disease characterization as it enables the simultaneous measurement of molecular, functional, and anatomical information in soft tissues of the body. Because of this promise, companies such as Siemens, GE, and Philips have developed and are now offering combined PET/MR systems. However, one of the challenges affecting the long-term impact of this technology is the current cost ($5-6M) due to the huge investment required by a company to develop an integrated product, and the need for the user to purchase both PET and MRI sub-systems. Our lab is addressing these issues by creating the world's first RF-penetrable PET ring, which can in principle be inserted into any existing MR system, while still allowing use of the built-in MR RF transmit coil. This would avoid the expensive integration of the two modalities, which, up to now, in order to achieve whole-body PET/MR, has required substantial modifications to the MR system, including re-engineering the body transmit coil sub-system to reside inside the PET ring. Thus, the proposed technology would substantially lower the cost barrier for an existing MR site to upgrade to PET/MR capability since they would just need to purchase the RF-transmissive PET insert, and it also would reduce the industry investment to achieve integrated PET/MRI. Hypothesis: Using the novel electro-optical signal transmission scheme proposed, we can create a PET insert that is penetrable to a RF field and thus can achieve simultaneous ToF-PET/MR using the built in body transmit coil of an MR system. The basic idea to enable the PET ring insert to be RF-penetrable (i.e. for the RF field to leak inside of the PET ring) is to have it electrically floating with respect to the MR system, and to have small gaps between PET detector modules where the field lines can leak in. This floating PET ring is made possible via the concept of "electro-optical" signal transmission, which draws from the field of telecommunications; in our formulation, the fast scintillation detector signals are coupled to tiny lasers, converted to near infrared light, and transmitted down long telecommunications-grade optical fibers, thus enabling electrical isolation from the MR system. In addition, since the electro-optical approach uses optical fibers, it substantially reduces the electrical footprint within the MR system compared to a PET system design that uses long electrical cables, while achieving excellent spatial, energy, and temporal resolutions required for PET. In this project, we will develop a full proof-of-principle of this RF-penetrable concept via a brain-size PET insert, and test its RF transmissivity in a 3T MRI system. In order to achieve these goals, we explore many innovative concepts.