Combined Multi-Pinhole and Fan-Beam Brain SPECT

描述（由申请人提供）：最近FDA批准SPECT成像剂I-123标记的DaTscan用于诊断和监测帕金森病（PD）的进展，开辟了SPECT脑成像的新时代。与其中整个大脑是感兴趣体积的灌注成像不同，PD的感兴趣结构是位于大脑内部的壳核和尾状核（以及潜在的黑质）。然而，PD还需要枕叶成像来计算纹状体结合率（SBR），这是一个在早期诊断和区分PD与具有相似临床表现的其他疾病中具有重要意义的参数。我们的假设是，将一个探测器头上的专门设计的MPH准直器与当前双头SPECT系统的剩余头上的扇形束准直器结合，再加上具有建模系统空间分辨率的迭代重建，将导致以边际成本（准直器和重建软件的价格）改善对大脑内部区域中的结构的检测和量化。MPH准直器将被设计为提供针对大脑内部的增强的空间分辨率/灵敏度。扇形束准直器将提供更低的 分辨率但完整的大脑采样解决了数据的充分性，并允许在枕叶上定义感兴趣的体积以计算SBR。在临床上，这将提供一种低成本的系统，其允许对大脑内部区域中的结构的功能进行改进的可视化和相对量化，所述内部区域可能小至~4 mm的黑质，这目前除了昂贵的大脑专用SPECT系统之外无法实现。这将极大地影响PD的早期检测和区分，并且随着新的SPECT成像剂被批准，可能影响其他神经系统疾病。我们研究假设的方法分为两个具体目标。第一个具体目标是通过基于任务的性能研究选择在第二个具体目标下进行比较的MPH准直器设计，并开发MPH和扇束准直器的组合重建以实现这种比较。第二个具体目标是执行基于任务的优化，然后比较基于使用Chelelized Hoteling Observer（CHO）检测的所选设计和通过SBR计算定量纹状体功能。使用这些基于任务的标准，我们将研究分辨率与灵敏度之间的权衡，通过针孔直径的变化，以及通过明智地使用不强制每个针孔照射的检测器部分的唯一性（允许多路复用）来提高灵敏度的方法，以及安装针孔的板的曲率，以使侧面和头部针孔更接近患者。

DESCRIPTION (provided by applicant): The recent FDA approval of the SPECT imaging agent I-123 labeled DaTscan for diagnosis and monitoring progression of Parkinson's Disease (PD) has open up a new era in SPECT brain imaging. Unlike with perfusion imaging where the entire brain is the volume of interest, with PD the structures of interest are the putamen and caudate (and potentially substantia nigra) which lie in the interior portion of the brain. However imaging of the occipital lobe is also required with PD for calculation of the striatal binding rati (SBR), a parameter of significance in the early diagnosis and differentiation of PD from other disorders with similar clinical presentations. Our hypothesis is that combining a specifically designed MPH collimator on one detector head with a fan-beam collimator on the remaining head of current dual-headed SPECT systems, coupled with iterative reconstruction with modeling system spatial resolution, will result in improved detection and quantification of structures in the interior region of the brain at marginal cost (the price of collimator(s) and reconstruction software). The MPH collimator would be designed to provide enhanced spatial resolution / sensitivity for the interior of the brain. The fan-beam collimator would provide lower resolution but complete sampling of the brain addressing data sufficiency and allowing a volume-of-interest to be defined over the occipital lobe for calculation of SBR's. Clinically this would provide a low-cost system allowing improved visualization and relative quantification of function of structures in the interior region of the brain, potentially as small as the ~4 mm substantia nigra, which cannot currently be achieved by other than expensive, brain dedicated, SPECT systems. This would greatly impact the early detection and differentiation of PD, and possibly other neurological disorders as new SPECT imaging agents are approved. Our approach for investigating our hypothesis is organized into two specific aims. The first specific aim is to select the MPH collimator designs to be compared under the second specific aim by task-based performance studies, and develop the combined reconstruction of MPH and fan-beam collimators to enable this comparison. The second specific aim is to perform task-based optimization and then comparison of the selected designs based on detection using the Channelized Hoteling Observer (CHO) and quantification of striatal function by calculation of the SBR. Using these task-based criteria we will investigate the trade-off of resolution versus sensitivity by variation in the diameter of the pinholes, and ways to improve sensitivity through judicious usage of not enforcing uniqueness in the portion of the detector irradiated by each pinhole (allowing multiplexing), and curvature of the plate the pinholes are mounted on to bring the lateral and cranial pinholes closer to the patient.