Raylman Raymond R, Majewski Stan, Velan S Sendhil, Lemieux Susan, Kross Brian, Popov Vladimir, Smith Mark F, Weisenberger Andrew G
Center for Advanced Imaging, Department of Radiology, West Virginia University, Morgantown, WV 26506, USA.
J Magn Reson. 2007 Jun;186(2):305-10. doi: 10.1016/j.jmr.2007.03.012. Epub 2007 Mar 24.
Multi-modality imaging (such as PET-CT) is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET, fused with anatomical images created by MRI, allow the correlation of form with function. Perhaps more exciting than the combination of anatomical MRI with PET, is the melding of PET with MR spectroscopy (MRS). Thus, two aspects of physiology could be combined in novel ways to produce new insights into the physiology of normal and pathological processes. Our team is developing a system to acquire MRI images and MRS spectra, and PET images contemporaneously. The prototype MR-compatible PET system consists of two opposed detector heads (appropriate in size for small animal imaging), operating in coincidence mode with an active field-of-view of approximately 14 cm in diameter. Each detector consists of an array of LSO detector elements coupled through a 2-m long fiber optic light guide to a single position-sensitive photomultiplier tube. The use of light guides allows these magnetic field-sensitive elements of the PET imager to be positioned outside the strong magnetic field of our 3T MRI scanner. The PET scanner imager was integrated with a 12-cm diameter, 12-leg custom, birdcage coil. Simultaneous MRS spectra and PET images were successfully acquired from a multi-modality phantom consisting of a sphere filled with 17 brain relevant substances and a positron-emitting radionuclide. There were no significant changes in MRI or PET scanner performance when both were present in the MRI magnet bore. This successful initial test demonstrates the potential for using such a multi-modality to obtain complementary MRS and PET data.
多模态成像（如PET-CT）正迅速成为疾病诊断和新药研发中的一项重要工具。PET生成的功能图像与MRI创建的解剖图像相融合，能够实现形态与功能的关联。或许比解剖学MRI与PET的结合更令人兴奋的是PET与磁共振波谱（MRS）的融合。这样一来，生理学的两个方面可以以全新的方式结合起来，从而为正常和病理过程的生理学提供新的见解。我们的团队正在开发一种系统，用于同时采集MRI图像、MRS波谱和PET图像。这款与MR兼容的PET系统原型由两个相对的探测器头组成（尺寸适合小动物成像），以符合模式运行，有效视野直径约为14厘米。每个探测器由一组LSO探测器元件组成，通过一根2米长的光纤光导与一个单位置灵敏光电倍增管相连。光导的使用使得PET成像仪的这些磁场敏感元件能够放置在我们3T MRI扫描仪的强磁场之外。PET扫描仪成像仪与一个直径12厘米、12臂的定制鸟笼线圈集成在一起。从一个多模态体模成功采集到了同时的MRS波谱和PET图像（该体模由一个填充了17种与脑相关物质的球体和一种正电子发射放射性核素组成）。当MRI和PET扫描仪同时置于MRI磁体孔内时，它们的性能没有显著变化。这次成功的初步测试证明了使用这种多模态获取互补的MRS和PET数据的潜力。
