Department of Radiology, University of Wisconsin, Madison, Wisconsin
PET/MR Engineering, GE Healthcare, Waukesha, Wisconsin; and.
J Nucl Med. 2021 Feb;62(2):287-292. doi: 10.2967/jnumed.120.245597. Epub 2020 Jul 9.
Standard clinical reconstructions usually require several minutes to complete, and this time is mostly independent of the duration of the data being reconstructed. Applications such as data-driven motion estimation, which require many short frames over the duration of the scan, become unfeasible with such long reconstruction times. In this work, we present an infrastructure whereby ultra-fast list-mode reconstructions of very short frames (≤1 s) are performed. With this infrastructure, it is possible to have a dynamic series of frames that can be used for various applications, such as data-driven motion estimation, whole-body surveys, quick reconstructions of gated data to select the optimal gate for a given attenuation map, and, if the infrastructure runs simultaneously with the scan, real-time display of the reconstructed data during the scan and automated alerts for patient motion. A fast ray-tracing time-of-flight projector was implemented and parallelized. The reconstruction parameters were optimized to allow for fast performance: only a few iterations are performed, without point-spread-function modeling, and scatter correction is not used. The resulting reconstructions are thus not quantitative but are acceptable for motion estimation and visualization purposes. Data-driven motion can be estimated using image registration, with the resultant motion data being used in a fully motion-corrected list-mode reconstruction. The infrastructure provided images that can be used for visualization and gating purposes and for motion estimation using image registration. Several case studies are presented, including data-driven motion estimation and correction for brain studies, abdominal studies in which respiratory and cardiac motion is visible, and a whole-body survey. The presented infrastructure provides the capability to quickly create a series of very short frames for PET data that can be used in a variety of applications.
标准的临床重建通常需要几分钟才能完成，而且这段时间主要与重建数据的时长无关。对于需要在扫描期间获取多个短帧的应用，如数据驱动的运动估计，这样的长重建时间是不可行的。在这项工作中，我们提出了一种基础设施，可以实现非常短帧（≤1 秒）的超快速列表模式重建。通过这种基础设施，可以获得一系列动态帧，可用于各种应用，如数据驱动的运动估计、全身扫描、门控数据的快速重建以选择给定衰减图的最佳门、如果基础设施与扫描同时运行，则可以在扫描期间实时显示重建数据，并自动发出患者运动的警报。实现了快速的射线追踪飞行时间投影器并对其进行了并行化处理。优化了重建参数以实现快速性能：仅执行少数迭代，不进行点扩散函数建模，也不使用散射校正。因此，重建结果不是定量的，但可以用于运动估计和可视化目的。可以使用图像配准来估计数据驱动的运动，然后将所得的运动数据用于完全运动校正的列表模式重建中。所提供的基础设施可以生成用于可视化和门控目的以及用于使用图像配准进行运动估计的图像。展示了几个案例研究，包括用于脑研究的数据驱动运动估计和校正、可以看到呼吸和心脏运动的腹部研究，以及全身扫描。所提出的基础设施提供了快速创建一系列非常短的 PET 数据帧的能力，这些帧可用于各种应用。
