Pre-clinical PET/MR: technological advances and new perspectives in biomedical research
Pre-clinical PET/MR: technological advances and new perspectives in biomedical research
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DOI：
10.1007/s00259-009-1078-0
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发表时间：
2009-03-01
影响因子：
9.1
通讯作者：
Pichler, Bernd J.
中科院分区：
文献类型：
--
作者：
Wehrl, Hans F.;Judenhofer, Martin S.;Pichler, Bernd J.
组合PET/MRI允许多参数成像，并同时沿着高分辨率形态学揭示一个或多个功能过程。特别是在小动物研究中，需要高的软组织对比度，扫描时间以及辐射剂量是关键因素，与PET/CT相比，PET和MRI的组合将是有益的。在20世纪90年代中期，几个研究小组使用不同的方法将PET探测器集成到高场MRI中。首先，系统基于将闪烁光引导到PMT的光纤，PMT位于边缘磁场之外。伽马射线探测器技术的最新进展主要是由雪崩光电二极管（APD）的出现以及快速闪烁材料（如氧正硅酸镥（LSO））的常规可用性引发的，为开发完全磁场不敏感的高性能PET探测器铺平了道路。对当前的动物PET/MR技术进行了回顾，并指出了在设计PET和高性能PET的完全集成时存在的缺陷。场MRI进行了讨论。紧凑型PET探测器可以集成在小口径、高场MRI断层扫描仪中。详细的性能评估表明，两个成像系统之间的相互干扰可以最小化。所有主要MR应用的性能，从T1或T2加权成像到功能性MRI（fMRI）或磁共振波谱（MRS）的回波平面成像（EPI），都可以保持，即使PET插入器内置在MRI中并同时采集PET数据。PET系统的性能不受静磁场或MRI序列的影响，其最初的生物医学研究应用范围从PET的功能信息与MRI的解剖信息的结合到结合代谢PET和MRI数据的多功能成像，与其他多模态方法相比，PET/MR提供了大量互补的功能和解剖信息。利用这种新的成像方式同时获得PET和MRI数据的能力可能对小动物成像研究产生巨大影响。
Combined PET/MRI allows for multi-parametric imaging and reveals one or more functional processes simultaneously along with high-resolution morphology. Especially in small-animal research, where high soft tissue contrast is required, and the scan time as well as radiation dose are critical factors, the combination of PET and MRI would be beneficial compared with PET/CT.In the mid-1990's, several research groups used different approaches to integrate PET detectors into high-field MRI. First, systems were based on optical fibres guiding the scintillation light to the PMT's, which reside outside the fringe magnetic field. Recent advances in gamma ray detector technology, which were initiated mainly by the advent of avalanche photodiodes (APD's) as well as the routine availability of fast scintillation materials like lutetium oxyorthosilicate (LSO), paved the way towards the development of fully magnetic-field-insensitive high-performance PET detectors.Current animal PET/MR technologies are reviewed and pitfalls when engineering a full integration of a PET and a high-field MRI are discussed. Compact PET detectors can be integrated in small-bore, high-field MRI tomographs. Detailed performance evaluations have shown that the mutual interference between the two imaging systems could be minimized. The performance of all major MR applications, ranging from T1- or T2-weighted imaging up to echo-planar imaging (EPI) for functional MRI (fMRI) or magnetic resonance spectroscopy (MRS), could be maintained, even when the PET insert was built into the MRI and acquiring PET data simultaneously. Similarly, the PET system performance was not influenced by the static magnetic field or applied MRI sequences.Initial biomedical research applications range from the combination of functional information from PET with the anatomical information from the MRI to multi-functional imaging combining metabollic PET and MRI data.Compared to other multi-modality approaches PET/MR offers a multitude of complementary function and anatomical information. The ability to obtain simultaneous PET and MRI data with this new imaging modality could have tremendous impact on small animal imaging research.