Section Biomedical Imaging, Delft University of Technology, Delft, Netherlands.
Phys Med Biol. 2018 Nov 7;63(22):225002. doi: 10.1088/1361-6560/aae76c.
SPECT can be used to image dopamine transporter (DaT) availability in the human striatum, e.g. for diagnosis of Parkinson's disease (PD). As traditional SPECT provides limited resolution and sensitivity, we proposed a full ring focusing multi-pinhole SPECT system (G-SPECT-I (Beekman 2015 Eur. J. Nucl. Med. Mol. Imaging 42 S209)) which demonstrated a 2.5 mm reconstructed resolution in phantom scans. G-SPECT-I achieves data completeness in the scan region of interest by translating the patient bed with an xyz-stage and combining projections from all bed positions into image reconstruction using a scanning focus method (SFM). This paper aims to develop dedicated SFM parameters for performing a DaTscan with high effective sensitivity and appropriate sampling. To this end, the axial scanning length was restricted and transaxial bed trajectories with a reduced number of positions based on a convex hull data-completeness model were tested. Quantitative accuracy was assessed using full G-SPECT-I simulations of an Alderson phantom based on measured system matrices. For each sampling strategy, the specific binding ratio (SBR) and asymmetry index (AI) in the left and right striatum, as well as the Localized SBR (L-SBR) and the Localized AI (L-AI) in eight striatal sub-regions were calculated and compared to those of the reference scan which performs full brain oversampling using 112 bed positions. Results show that structures essential for PD diagnosis were visually and quantitatively barely affected even when using the lowest number of bed translations (i.e. 4). The maximum deviation from the reference was only 1.5%, 1.5%, 5.5% and 7.0% for the SBR, AI, L-SBR and L-AI, respectively, when 4 positions were used. Thus, it is possible to perform an accurate DaTscan with a confined axial scan region and a limited number of focused bed positions. This enables protocols for extremely fast dynamic SPECT scans with less than half-minute time frames, which can be useful for motion correction.
SPECT 可用于成像人类纹状体中的多巴胺转运体 (DaT) 可用性，例如用于诊断帕金森病 (PD)。由于传统的 SPECT 提供的分辨率和灵敏度有限，我们提出了一种全环聚焦多针孔 SPECT 系统 (G-SPECT-I (Beekman 2015 Eur. J. Nucl. Med. Mol. Imaging 42 S209))，该系统在体模扫描中证明了 2.5mm 的重建分辨率。G-SPECT-I 通过使用 xyz 台平移患者床，并使用扫描焦点方法 (SFM) 将所有床位的投影组合到图像重建中，从而在感兴趣的扫描区域实现数据完整性。本文旨在开发专用的 SFM 参数，以实现具有高有效灵敏度和适当采样的 DaT 扫描。为此，限制了轴向扫描长度，并基于凸壳数据完整性模型测试了具有较少床位位置的横轴床轨迹。使用基于测量系统矩阵的 Alderson 体模的全 G-SPECT-I 模拟评估定量准确性。对于每种采样策略，计算并比较左和右纹状体中的特异性结合比 (SBR) 和不对称指数 (AI)，以及八个纹状体亚区中的局部 SBR (L-SBR) 和局部 AI (L-AI) 与使用 112 个床位位置进行全脑过采样的参考扫描的结果。结果表明，即使使用最少数量的床位平移（即 4 个），对 PD 诊断至关重要的结构在视觉和定量上几乎没有受到影响。当使用 4 个位置时，SBR、AI、L-SBR 和 L-AI 的最大偏差仅分别为 1.5%、1.5%、5.5%和 7.0%。因此，有可能在受限的轴向扫描区域和有限数量的聚焦床位位置执行精确的 DaT 扫描。这使得具有不到半分钟时间框架的极快速动态 SPECT 扫描协议成为可能，这对于运动校正可能很有用。
