IEEE Trans Med Imaging. 2020 Jan;39(1):119-128. doi: 10.1109/TMI.2019.2921969. Epub 2019 Jun 10.
Recently introduced stationary dedicated cardiac SPECT scanners provide new opportunities to quantify myocardial blood flow (MBF) using dynamic SPECT. However, comparing to PET, the low sensitivity of SPECT scanners affects MBF quantification due to the high noise level, especially for Thallium (Tl) due to its typically low injected dose. The conventional indirect method for generating parametric images typically starts by reconstructing a time series of frame images followed by fitting the time-activity curve (TAC) for each voxel or segment with an appropriate kinetic model. The indirect method is simple and easy to implement; however, it usually suffers from substantial image noise that could also lead to bias. In this paper, we developed a list mode direct parametric image reconstruction algorithm to substantially reduce noise in MBF quantification using dynamic SPECT and allow for patient radiation dose reduction. GPU-based parallel computing was used to achieve more than 2000-fold acceleration. The proposed method was evaluated in both simulation and in vivo canine studies. Compared with the indirect method, the proposed direct method achieved substantially lower image noise and variability, particularly at large number of iterations and at low-count levels.
最近推出的固定式专用心脏 SPECT 扫描仪为使用动态 SPECT 定量心肌血流 (MBF) 提供了新的机会。然而，与 PET 相比，SPECT 扫描仪的低灵敏度会由于噪声水平高而影响 MBF 的定量，尤其是对于铊 (Tl)，因为其典型的注入剂量低。传统的生成参数图像的间接方法通常从重建一系列帧图像开始，然后使用适当的动力学模型拟合每个体素或段的时间-活性曲线 (TAC)。间接方法简单且易于实现；然而，它通常会受到大量图像噪声的影响，这也可能导致偏差。在本文中，我们开发了一种列表模式直接参数图像重建算法，以使用动态 SPECT 显著降低 MBF 定量中的噪声，并允许减少患者的辐射剂量。基于 GPU 的并行计算被用于实现超过 2000 倍的加速。该方法在模拟和体内犬研究中进行了评估。与间接方法相比，所提出的直接方法在大量迭代和低计数水平下实现了更低的图像噪声和可变性。
