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

描述(申请人提供)：提出了一种用于扫描小型实验动物的双模式成像设备。该设备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，双模式成像在医学成像领域的新创新中经历了最大的商业成功。成功的组合是核素(SPECT和PET)与计算机断层扫描(CT)相结合。多模式产品的成功延伸到了小动物实验室，在那里，这项提议的发起人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。虽然CT图像提供了足够的分辨率来描述解剖细节，但这种方法仍然存在难以解决的缺点。采集速度、软组织对比度以及成像功能、动态和靶向分子相互作用的能力都是CT成像的局限性。MR的使用提供了CT的解剖信息，但也解决了上述局限性。另外，纵向实验，即在很长一段时间内对同一动物进行多次测量，在CT中尤其会受到分次放射治疗剂量的影响。MR不会通过增加高水平的辐射剂量来影响实验。Gamma Medica-IDEAS正在申请快速通道第一阶段/第二阶段SBIR赠款，以资助SPECT/MRI设备的开发。这一组合的技术挑战超过了涉及CT的技术挑战，主要是因为当两种模式放在一起时会发生交叉污染：MR场排除了与SPECT相关的光电倍增管(PMT)和运动；SPECT仪器的存在和电磁发射可能会改变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。CZT材料已被证明受到强磁场的影响最小。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)的强磁场下运行时对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式、多针孔、多探测器CZT SPECT的断层图像质量，以及为第二阶段原型选择4.7吨主动屏蔽超导磁体(内部、非政府GMI投资)。在第二阶段期间，将进行SPECT底盘的制造及其与磁共振成像系统的集成。在第一阶段/第二阶段结束时，Gamma Medica将准备创建SPECT/MRI试点产品。高磁场中的静态层析核成像是该项目的主要创新。用于活体小动物成像的双模式SPECT-MRI项目是活体受试者多模式成像设备发展的具有挑战性的下一步。核成像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，有望提供更丰富的结果。这项申请描述了一种创新的核成像技术，该技术可以独特地设计成与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.