Tuna Uygar, Johansson Jarkko, Ruotsalainen Ulla
Department of Signal Processing and BioMediTech, Tampere University of Technology, P.O. Box 533, 33101 , Tampere, Finland,
Ann Nucl Med. 2014 Jun;28(5):417-29. doi: 10.1007/s12149-014-0832-y. Epub 2014 Mar 20.
The aim of the study was (1) to evaluate the reconstruction strategies with dynamic [¹¹C]-raclopride human positron emission tomography (PET) studies acquired from ECAT high-resolution research tomograph (HRRT) scanner and (2) to justify for the selected gap-filling method for analytical reconstruction with simulated phantom data.
A new transradial bicubic interpolation method has been implemented to enable faster analytical 3D-reprojection (3DRP) reconstructions for the ECAT HRRT PET scanner data. The transradial bicubic interpolation method was compared to the other gap-filling methods visually and quantitatively using the numerical Shepp-Logan phantom. The performance of the analytical 3DRP reconstruction method with this new gap-filling method was evaluated in comparison with the iterative statistical methods: ordinary Poisson ordered subsets expectation maximization (OPOSEM) and resolution modeled OPOSEM methods. The image reconstruction strategies were evaluated using human data at different count statistics and consequently at different noise levels. In the assessments, 14 [¹¹C]-raclopride dynamic PET studies (test-retest studies of 7 healthy subjects) acquired from the HRRT PET scanner were used. Besides the visual comparisons of the methods, we performed regional quantitative evaluations over the cerebellum, caudate and putamen structures. We compared the regional time-activity curves (TACs), areas under the TACs and binding potential (BPND) values.
The results showed that the new gap-filling method preserves the linearity of the 3DRP method. Results with the 3DRP after gap-filling method exhibited hardly any dependency on the count statistics (noise levels) in the sinograms while we observed changes in the quantitative results with the EM-based methods for different noise contamination in the data. With this study, we showed that 3DRP with transradial bicubic gap-filling method is feasible for the reconstruction of high-resolution PET data with missing sinogram bins. The calculated intraclass correlation coefficient (ICC) values were similar for all tested methods and validated the test-retest study. The gap-filling and 3DRP method can be used for quantitative PET studies in which high temporal information is crucial and can serve as a reference method for comparison studies of the other reconstruction methods.
本研究的目的是：（1）利用从ECAT高分辨率研究断层扫描仪（HRRT）获得的动态[¹¹C] - 雷氯必利人体正电子发射断层扫描（PET）研究评估重建策略；（2）用模拟体模数据为选定的用于分析重建的间隙填充方法提供依据。
已实施一种新的经径向双立方插值方法，以实现对ECAT HRRT PET扫描仪数据更快的分析性三维重投影（3DRP）重建。使用数值Shepp-Logan体模，将经径向双立方插值方法与其他间隙填充方法进行视觉和定量比较。将这种新间隙填充方法的分析性3DRP重建方法的性能与迭代统计方法进行比较：普通泊松有序子集期望最大化（OPOSEM）和分辨率建模的OPOSEM方法。使用不同计数统计量（从而不同噪声水平）的人体数据评估图像重建策略。在评估中，使用了从HRRT PET扫描仪获得的14项[¹¹C] - 雷氯必利动态PET研究（7名健康受试者的重测研究）。除了对方法进行视觉比较外，我们还对小脑、尾状核和壳核结构进行了区域定量评估。我们比较了区域时间 - 活度曲线（TAC）、TAC下的面积和结合潜能（BPND）值。
结果表明，新的间隙填充方法保留了3DRP方法的线性。间隙填充后的3DRP结果在正弦图中几乎不依赖于计数统计量（噪声水平），而我们观察到基于期望最大化（EM）的方法在数据中存在不同噪声污染时定量结果会发生变化。通过本研究，我们表明采用经径向双立方间隙填充方法的3DRP对于重建具有缺失正弦图条带的高分辨率PET数据是可行的。所有测试方法计算的组内相关系数（ICC）值相似，并验证了重测研究。间隙填充和3DRP方法可用于高时间信息至关重要的定量PET研究，并可作为其他重建方法比较研究的参考方法。
