Enabling Multi-Tracer SPECT Studies of the Human Brain

项目摘要 分子成像提供了一种手段，定量研究人类大脑中的许多类型的过程， 微创方式。然而，大脑的复杂性导致在许多情况下， 希望能够同时研究一种以上的特性，例如测量神经受体结合 同时作为转运体或脑灌注与受体结合。虽然一种选择是 在某些情况下，如果要进行测量，则可以使用多种模态（例如PET/MR） 具有相似的灵敏度、空间分辨率和时间分辨率，则能够对多个探头进行成像 使用单一模态是有益的。因为SPECT利用标记有放射性核素的示踪剂， 在特定能量的伽马射线，它经常被吹捧为它的成像多种放射性示踪剂的可能性 同步然而，由于能量有限，多示踪剂SPECT研究在实践中很少进行 传统伽马相机的分辨率需要复杂的校正方案来解决 不同能量通道之间的串扰。高纯锗（HPGe）探测器技术提供 能量分辨率比传统的碘化钠基伽马射线提高了一个数量级 照相机，允许容易地分离相关放射性核素泄漏（例如，140 keV的99 mTc和159 keV的159 mTc）。 keV的123 I）和使用窄的能量窗口，显着减少散射。我们以前有 证明了机械冷却HPGe探测器SPECT的适用性，并在这里提出追求 该技术的进一步改进，包括增加的晶体尺寸和改善的固有空间 分辨率模块化相机的使用促进了具有良好性能的专用SPECT系统的设计。 空间分辨率、灵敏度和角度采样。我们将设计一个大脑特异性SPECT系统， 基于改进的方法对两种或更多种分子探针进行同时定量测量， HPGe探测器技术。与探测器的开发并行，我们将演示多示踪剂 通过非人类灵长类动物SPECT扫描的方法，将使用双相机原型获得 系统我们将利用分析，模拟和实验研究，在开发一个设计的SPECT 人类大脑成像系统为多示踪剂研究提供了前所未有的能力。

Project Summary Molecular imaging provides the means to quantitatively study many types of processes in the human brain in a minimally invasive manner. However, the complexity of the brain results in many instances in which it is desirable to be able to study more than one property simultaneously, such as measuring neuroreceptor binding at the same time as transporters or cerebral perfusion together with receptor occupancy. While one option for doing so in some cases may be to use multiple modalities (e.g. PET/MR), if the measurements are to be done with similar sensitivity, spatial resolution, and temporal resolution, then the ability to image multiple probes using a single modality is beneficial. Because SPECT utilizes tracers labeled with radionuclides that emit gamma rays at specific energies, it is often touted for its possibility of imaging multiple radiotracers simultaneously. However, multi-tracer SPECT studies are rarely done in practice due to the limited energy resolution of conventional gamma cameras that necessitates complicated correction schemes to account for crosstalk between the different energy channels. High-purity germanium (HPGe) detector technology provides an order of magnitude improvement in energy resolution over conventional sodium iodide-based gamma cameras, allowing for easy separation of relevant radionuclide photopeaks (e.g. 140 keV for 99mTc and 159 keV for 123I) and the use of narrow energy windows that significantly reduces scatter. We previously have demonstrated the applicability of mechanically-cooled HPGe detectors to SPECT and here propose to pursue further improvements in the technology, including increased crystal size and improved intrinsic spatial resolution. The use of modular cameras facilitates the design of application-specific SPECT systems with good spatial resolution, sensitivity, and angular sampling. We will design a brain-specific SPECT system capable of making simultaneous, quantitative measurements of two or more molecular probes based on the improved HPGe detector technology. In parallel with the detector developments we will demonstrate the multi-tracer methodology through non-human primate SPECT scans that will be acquired using a two-camera prototype system. We will utilize analytical, simulation, and experimental studies in developing a design for a SPECT system for human brain imaging offering unprecedented capabilities for multi-tracer studies.