Comparison of list-mode and DIRECT approaches for time-of-flight PET reconstruction.
Comparison of list-mode and DIRECT approaches for time-of-flight PET reconstruction.
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DOI：
10.1109/tmi.2012.2190088
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发表时间：
2012-07
影响因子：
10.6
通讯作者：
Karp JS
中科院分区：
文献类型：
--
作者：
Daube-Witherspoon ME;Matej S;Werner ME;Surti S;Karp JS
飞行时间（TOF）PET系统的早期临床结果已经证明了TOF信息在PET重建中的优势。TOF-PET系统中的重建方法包括列表模式和分箱迭代算法以及置信度加权分析方法。列表模式迭代TOF重建保留了空间和时间域中数据的分辨率，而无需任何分箱近似，但计算密集。我们开发了一种方法[DIRECT（TOF的直接图像重建）]来加速TOF-PET重建，该方法利用TOF数据的角度采样要求降低，方法是将列表模式数据分组为少量的方位角视图和共极倾斜，并将分组的事件存入组织图像，具有最终图像的采样和几何形状的阵列。所有的物理效应都包含在系统模型中，并存储在相同的组织图像结构中。使用组织图像允许在重建期间进行有效的计算，而无需射线跟踪或插值操作。DIRECT方法与宾夕法尼亚大学研究LaBr 3 TOF-PET扫描仪上采集的体模和患者数据的3D列表模式TOF有序子集期望最大化（OSEM）重建进行了比较。在不考虑代码优化的情况下，使用DIRECT进行这些研究的总处理和重建时间约为列表模式TOF-OSEM的25-30%，以实现相当的图像质量。此外，DIRECT的重建时间与事件的数量和/或空间和TOF内核的大小无关，而列表模式TOFOSEM的时间随着更多的事件或更大的内核而增加。DIRECT方法能够在减少的时间内在测量数据中定性和定量地再现列表模式迭代TOF重建的图像质量。
Early clinical results with time-of-flight (TOF) PET systems have demonstrated the advantages of TOF information in PET reconstruction. Reconstruction approaches in TOF-PET systems include list-mode and binned iterative algorithms as well as confidence-weighted analytic methods. List-mode iterative TOF reconstruction retains the resolutions of the data in the spatial and temporal domains without any binning approximations but is computationally intensive. We have developed an approach [DIRECT (direct image reconstruction for TOF)] to speed up TOF-PET reconstruction that takes advantage of the reduced angular sampling requirement of TOF data by grouping list-mode data into a small number of azimuthal views and co-polar tilts and depositing the grouped events into histo-images, arrays with the sampling and geometry of the final image. All physical effects are included in the system model and deposited in the same histo-image structure. Using histo-images allows efficient computation during reconstruction without ray-tracing or interpolation operations. The DIRECT approach was compared with 3D list-mode TOF ordered subsets expectation maximization (OSEM) reconstruction for phantom and patient data taken on the University of Pennsylvania research LaBr3 TOF-PET scanner. The total processing and reconstruction time for these studies with DIRECT without attention to code optimization is approximately 25–30% that of list-mode TOF-OSEM to achieve comparable image quality. Furthermore, the reconstruction time for DIRECT is independent of the number of events and/or sizes of the spatial and TOF kernels, while the time for list-mode TOFOSEM increases with more events or larger kernels. The DIRECT approach is able to reproduce the image quality of list-mode iterative TOF reconstruction both qualitatively and quantitatively in measured data with a reduced time.