OPTIMIZATION OF RCBF MEASUREMENT WITH A 3D PET SCANNER

该项目(于1994年7月启动)的目标是确定一个 进行脑功能地形图研究的最佳方法 三维PET和用于测量的示踪剂O2-I5水 局部脑血流量(RCBF)。当前的断层摄影术，例如 GE Advance最近被NIH收购，允许3D图像采集 和重建，大大提高了扫描仪的灵敏度。 然而，图像噪声在rCBF的高计数率下增加 通常进行团注0-I5水的研究。 因此，尽管对于低计数率，信噪比有所改善 研究表明，在高计数率下，改善要小得多。作为一名 结果，人们可以用较少的量进行CBF研究 放射性，但不可能注入当前使用的 相当于改善了信号。有几个因素会影响 每MCI注入的信号，包括每MCI的放射性数量 注射、注射次数、注射长度和类型。 他将进行研究，以找到这些因素的最佳组合 GE高级断层扫描仪的参数。模拟、虚拟和 将进行人体实验。 将进行模拟来计算大脑的放射性 这是由于0-5注水量和剖面不同造成的， 和不同的扫描长度。此外，还将获得有关大脑的数据 以前从扫描中注射的0-15 mci水的每MCI放射性 采用Sanditronix PC2048-15B断层扫描仪。扫描数据将 然后在GE高级扫描仪上使用大脑模型获得 在一定的计数速率范围内充满衰变的放射性，以及 图像噪声将根据扫描仪中特定的MCI来确定 扫描长度。模型研究的结果将被他用来 估计大脑产生的信噪比特性 预测的不同扫描方案的放射性水平 模拟。基于这些结果，对人类的研究将是 使用选定的注射方案执行，同时执行 激活特定大脑区域的功能任务。有能力 使用不同协议检测激活焦点将通过以下方式确定 用统计参数映射软件对PET图像进行分析。 理想情况下，将确定扫描方案以优化检测 给定总量的放射性的激活焦点 管理。

The goal of the project (initiated in July 1994) is to determine an optimal method for performing functional brain mapping studies with three-dimensional PET and oxygen-I5 water, a tracer used to measure regional cerebral blood flow (rCBF). Current tomographs, such as the GE Advance recently acquired by the NIH, permit 3D image acquisition and reconstruction, substantially increasing scanner sensitivity. However, image noise increases at the high count rates at which rCBF studies with bolus injections of 0-I5 water are typically performed. Thus, although the signal-to-noise ratio improves for low count rate studies, the improvement is much less at high count rates. As a result, one can perform CBF studies with smaller amounts of radioactivity, but it is not possible to inject the currently-used amounts to improve signal. There are several factors which affect the signal per mCi injected, including amount of radioactivity per injection, number of injections, and length and type of injection. Studies will he performed to find an optimal combination of these parameters for the GE Advance tomograph. Simulation, phantom, and human experiments will be performed. Simulations will be carried out to calculate the brain radioactivity that results from different 0-I5 water injection amounts and profiles, and varying scan lengths. In addition, data will be obtained on brain radioactivity per mCi of 0-15 water injected from scans previously performed with the Scanditronix PC2048-15B tomograph. Scan data will then be obtained on the GE Advance scanner using a brain phantom filled with decaying radioactivity for a range of count rates, and image noise will be determined per mCi in the scanner for specific scan lengths. The results of the phantom studies will he used to estimate the signal to noise properties resulting from the brain radioactivity levels for different scan protocols as predicted by the simulations. Based on these results, studies in humans will be performed with selected injection protocols while they perform a functional task that activates specific brain regions. The ability to detect activation foci with different protocols will be determined by analyzing the PET images with Statistical Parametric Mapping software. Ideally, a scan protocol will be determined to optimize detection of activation foci for a given total amount of radioactivity administered.