Development of a PET/OMRI combined system for simultaneous imaging of positron and free radical probes for small animals
Development of a PET/OMRI combined system for simultaneous imaging of positron and free radical probes for small animals
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DOI：
10.1118/1.4963215
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发表时间：
2016-10-01
期刊：
影响因子：
3.8
通讯作者：
Hatazawa, Jun
中科院分区：
文献类型：
--
作者：
Yamamoto, Seiichi;Watabe, Tadashi;Hatazawa, Jun
目的：正电子发射断层扫描（PET）对受试者体内放射性示踪剂分布的成像具有高灵敏度。然而，不可能通过PET对对象中的自由基分布进行成像。由于自由基是相当活跃的，它们与许多疾病有关，包括但不限于癌症、炎症、中风和心脏病。Overhauser增强磁共振成像（OMRI）是迄今为止唯一能显示体内自由基分布的方法。通过结合PET和OMRI，可以开发一种新的混合成像模式，可以同时对放射性示踪剂和自由基分布进行成像。为此，作者开发了一种PET/OMRI组合系统的小动物。方法：开发的PET/OMRI系统使用基于光纤的PET系统与基于永磁体的OMRI系统相结合。基于光纤的PET系统使用柔性光纤束。八个基于光纤的块检测器被布置在56 mm直径的环中以形成PET系统。LGSO块位于OMRI的视场（FOV）内，位置敏感光电倍增管位于OMRI后面，以最大限度地减少PET和OMRI之间的干扰。OMRI系统使用0.0165 T永磁体。该系统具有一个电子自旋共振线圈来增强MRI信号，利用Overhauser效应来成像PET/OMRI系统的FOV中的自由基。结果：基于光纤的PET系统的空间分辨率和灵敏度在中心FOV处分别为1.2mm FWHM和1.2%。OMRI系统对硝酰基自由基（NXR）溶液的分布进行成像。PET与OMRI之间干扰较小。同时成像的正电子放射性示踪剂和NXR的解决方案成功地进行了开发的PET/OMRI系统的幻影和小动物study.Conclusions：作者开发了一个PET/OMRI结合系统的潜力，提供有趣的新的结果在分子成像研究，如在体内的分子和自由基分布。(C)2016年美国医学物理学家协会。
Purpose: Positron emission tomography (PET) has high sensitivity for imaging radioactive tracer distributions in subjects. However, it is not possible to image free radical distribution in a subject by PET. Since free radicals are quite reactive, they are related to many diseases, including but not limited to cancer, inflammation, strokes, and heart disease. The Overhauser enhanced magnetic resonance imaging (OMRI) is so far the only method that images free radical distribution in vivo. By combining PET and OMRI, a new hybrid imaging modality might be developed that can simultaneously image the radioactive tracer and free radical distributions. For this purpose, the authors developed a PET/OMRI combined system for small animals.Methods: The developed PET/OMRI system used an optical fiber-based PET system combined with a permanent magnet-based OMRI system. The optical fiber-based PET system uses flexible optical fiber bundles. Eight optical fiber-based block detectors were arranged in a 56 mm diameter ring to form a PET system. The LGSO blocks were located inside the field-of-view (FOV) of the OMRI, and the position sensitive photomultiplier tubes were positioned behind the OMRI to minimize the interference between the PET and the OMRI. The OMRI system used a 0.0165 T permanent magnet. The system has an electron spin resonance coil to enhance the MRI signal using the Overhauser effect to image the free radical in the FOV of the PET/OMRI system.Results: The spatial resolution and sensitivity of the optical fiber-based PET system were 1.2 mm FWHM and 1.2% at the central FOV, respectively. The OMRI system imaged the distribution of a nitroxyl radical (NXR) solution. The interference between PET and OMRI was small. Simultaneous imaging of the positron radiotracer and the NXR solution was successfully conducted with the developed PET/OMRI system for phantom and small animal studies.Conclusions: The authors developed a PET/OMRI combined system with the potential to provide interesting new results in molecular imaging research, such as in vivo molecular and free radical distributions. (C) 2016 American Association of Physicists in Medicine.