Dual Modality SPECT-MRI for In-Vivo Small Animal Imaging

描述（由申请人提供）：提出了一种用于小实验动物扫描的双模成像设备。该装置是核医学仪器单光子发射计算机断层扫描（SPECT）和高场磁共振成像仪（MRI）的组合。在过去的10年里，双模成像在医学成像领域的创新中取得了最大的商业成功。成功的组合是核（SPECT和PET）结合计算机断层扫描（CT）。多模态产品的成功扩展到小动物实验室，该提案的发起者Gamma-Medica-Ideas已经安装了数十台SPECT/CT设备，最近推出并销售了几种PET/CT组合。尽管CT图像提供了足够的分辨率来描绘解剖细节，但这种方法仍然存在一些不容易解决的缺点。采集速度、软组织对比以及成像功能、动态和靶向分子相互作用的能力都是CT模式的限制。MR的使用提供了CT的解剖信息，但也解决了上述局限性。此外，纵向实验，即在很长一段时间内对同一只动物进行多次测量，在CT中尤其可能受到分次放射治疗剂量的影响。核磁共振不会通过增加高水平的辐射剂量来影响实验。Gamma Medica-Ideas正在申请快速通道I/II期SBIR拨款，以资助SPECT/MRI设备的开发。这种组合的技术挑战超过了涉及CT的挑战，主要是因为当两种模式靠近时发生的交叉污染：MR领域排除了光电倍增管（pmt）的使用和与SPECT相关的运动；SPECT仪器的存在和电磁发射可能改变MR和RF场，导致MR图像退化。Gamma Medica在开发基于半导体CZT的临床产品方面具有独特的地位。研究表明，CZT材料受强磁场的影响最小。该项目的第一阶段旨在评估和记录在近距离和高达4.7特斯拉(T)的强磁场中操作时对CZT图像质量的影响。第一阶段提案的其他目标包括确定固定，多针孔，多探测器CZT SPECT的断层成像质量，以及为第二阶段原型购买4.7 T主动屏蔽超导磁体的选择（由内部，非政府GMI投资）。在第二阶段，将进行SPECT底盘的制造及其与MRI系统的集成。在I/II期结束时，Gamma Medica将准备创建一个试点SPECT/ MRI产品。高磁场下的静止核层析成像是该项目的主要创新。双模态SPECT-MRI在体小动物成像项目是活体多模态成像设备发展的一个具有挑战性的下一步。核和计算机断层成像的互补性导致了对生物过程的协同理解，并减少了不必要的临床程序。MRI丰富的动态、化学、光谱和动态图像数据与SPECT的分子靶向成像相结合，可以提供更丰富的结果。本应用程序描述了一种创新的核成像技术，该技术可以独特地设计为与MRI兼容。

DESCRIPTION (provided by applicant): A dual-modality imaging device for the scanning of small laboratory animals is proposed. The device is a combination of single-photon emission computed tomography (SPECT), which is a nuclear medicine instrument, and a high-field magnetic resonance imager (MRI). Dual-modality imaging has experienced the most commercial success of new innovations in the medical imaging field during the past 10 years. The successful combinations have been nuclear (SPECT and PET) combined with computed tomography (CT). The success of the multi-modality products extends to the small animal laboratory, where Gamma-Medica-Ideas, the originator of this proposal, has installed dozens of SPECT/CT devices and recently introduced and sold several PET/CT combinations. Although the CT images provide sufficient resolution to depict anatomical detail, there remain drawbacks to this approach that cannot be easily addressed. Acquisition speed, soft tissue contrast, and the ability to image functional, dynamic, and targeted molecular interactions are all limitations to the CT modality. The use of MR provides the anatomical information of CT but also addresses the above limitations. An addition, longitudinal experiments, i.e., multiple measurements of the same animal over a long time period, can be especially affected in CT by what can be a fractionated radiation therapy dose. MR does not influence the experiment through the addition of high levels of radiation dose. Gamma Medica-Ideas is applying for Fast-Track Phase I/II SBIR grant to fund the development of the SPECT/MRI device. The technological challenges of this combination exceed those that involve CT, mainly because of the cross-contamination that occurs when the two modalities are put in proximity: the MR field precludes the use of photomultiplier tubes (PMTs) and motion associated with SPECT; and the presence and electro-magnetic emissions from the SPECT instrument can possibly change the MR and RF fields and cause MR image degradations. Gamma Medica has a unique position in having developed a clinical product based upon the semiconductor CZT. CZT material has been shown to be minimally affected by strong magnetic fields. Phase I of the project aims to evaluate and document the effects on CZT image quality when operated in close proximity and within strong magnetic fields up to 4.7 Tesla (T). Other aims of the Phase I proposal involve the determination of tomographic image quality of stationary, multi-pinhole, multi-detector CZT SPECT and the selection of a 4.7 T, actively shielded superconducting magnet to be purchased (with internal, non-governmental GMI investment) for the Phase II prototype. During Phase II the fabrication of the SPECT chassis and its integration with the MRI system will take place. At the conclusion of Phase I/II, Gamma Medica will be ready to create a pilot SPECT/ MRI product. Stationary tomographic nuclear imaging in a high-magnetic field is the project's primary innovation. The Dual-Modality SPECT-MRI for in vivo small animal imaging project is a challenging next step in the development of multi-modality imaging devices of living subjects. The complementary nature of nuclear and computed tomography imaging has resulted in synergistic understanding of biological processes and reduction in unnecessary clinical procedures. The rich dynamic, chemical, spectroscopic, and dynamic image data of MRI combined with the molecularly-targeted imaging of SPECT can be expected to provide even more fruitful results. This application describes an innovative nuclear imaging technology that uniquely can be engineered to be compatible with MRI.