Integration and characterization of highly performance readout architecture on an RF-penetrable brain PET Insert for simultaneous operation in MR scanner

从正电子发射断层扫描(PET)和核磁共振成像(MRI)中真正同时获取数据是核医学成像领域面临的新挑战。由于这些技术的互补结果，联合系统可以显著改进病变检测。第一个集成的PET/MR系统现在市场上，但缺点是非常昂贵，几乎阻碍了许多感兴趣的研究人员使用它们。因此，专用于特定身体区域的系统体积减小，是一种有效的替代方案，可以让更广泛的公众使用这种技术。尤其是斯坦福大学医学院的莱文·S博士团队的目标是一种可以通过射频脉冲穿透的脑部PET植入物，可以与任何现有的磁共振扫描仪结合使用，而不需要修改。这种插入物可能很便宜，有助于更好地了解联合成像在神经学应用中的真正好处。这一提议的候选者开发了高性能读出架构，集成在非常紧凑的ASIC上，符合PET插入物的要求。该电子器件的设计与MR环境中的操作兼容，并且已经达到了极好的时间分辨率，这是最佳图像重建所需的。该项目的目的是将开发的电子设备集成到一个非常紧凑的探测器单元上，并在磁共振环境中进行表征和操作。每个单元由700多个闪烁晶体组成，再加上硅光倍增器，并由24个ASIC并行读出。整个PET插入物将组装成多达16个单元，需要适当的同步和校准。插入件被设计成与MR接地隔离，以便允许RF脉冲通过它传输。如果成功，这种PET插入物可以与任何磁共振扫描仪一起使用，以广泛研究这些组合技术的好处。

Truly simultaneous data acquisition from Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRi) is a new challenge in nuclear medical imaging. Thanks to the complementary results of these technologies, a combined system could lead to significant improvements in lesions detection.The first integrated PET/MR systems are now on the market, with the drawback of being very expensive, then practically preventing their use by many interested researchers. For this reason, systems dedicated to specific body regions, with consequent reduced size, are a valid alternative which would make such technologies available to a wider public.In particular, Dr. Levin' s group at Stanford University School of Medicine is targeting a brain PET insert, penetrable by radio-frequency (RF) pulses, to be used in combination with any existing MR scanner, without need of modifications. This insert could be cheap and contribute to better understand the real benefits of combined imaging in neurological applications. The candidate of this proposal has developed highly performing readout architecture, integrated on a very compact ASIC, which matches the requirements of the PET insert. The electronics is designed for being compatible with operations in MR environment and has already achieved extremely good timing resolution, required for optimal image reconstruction. The aim of this project is the integration of the developed electronics on a very compact detector unit and its characterization and operation in MR environment. Each unit is composed of more than 700 scintillating crystals, coupled with Silicon Photo-Multipliers and read out by 24 ASICs in parallel.The whole PET insert would be assembled with up to 16 units, which need proper synchronization and calibration. The insert is designed to be isolated from MR ground, in order to allow the transmission of RF pulses through it. If successful, this PET insert could be used together with any MR scanner for extensively studying the benefits of these combined technologies.