Nuclear Medicine, KU Leuven, B-3000 Leuven, Belgium.
IEEE Trans Med Imaging. 2013 Feb;32(2):237-46. doi: 10.1109/TMI.2012.2220376. Epub 2012 Sep 21.
Positron emission tomographs (PETs) are currently almost exclusively designed as hybrid systems. The current standard is the PET/CT combination, while prototype PET/MRI systems are being studied by several research groups. One problem in these systems is that the transaxial field-of-view of the second system is smaller than that of the PET camera and does not provide complete attenuation data. Because this second system provides the image for PET attenuation and scatter correction, the smaller FOV causes truncation of the attenuation map, producing bias in the attenuation corrected activity image. In this paper, we propose a maximum-a-posteriori algorithm for estimating the missing part of the attenuation map from the PET emission data. The method is evaluated on five artificially truncated 18F-FDGPET/CT studies, where it reduced the error on the reconstructed PET activities from 20% to less than 7%. The results on a PET/MRI patient study with 18F-FDG are presented as well.
正电子发射断层扫描（PET）目前几乎都是作为混合系统来设计的。当前的标准是 PET/CT 组合，而一些研究小组正在研究原型 PET/MRI 系统。这些系统中的一个问题是，第二个系统的横向视野小于 PET 相机的视野，并且无法提供完整的衰减数据。由于这个第二个系统为 PET 衰减和散射校正提供图像，因此较小的 FOV 会导致衰减图的截断，从而导致衰减校正后的活性图像产生偏差。在本文中，我们提出了一种最大后验算法，用于从 PET 发射数据中估计衰减图的缺失部分。该方法在五个人为截断的 18F-FDG PET/CT 研究中进行了评估，结果表明该方法将重建的 PET 活性的误差从 20%降低到了 7%以下。还展示了在 18F-FDG 的 PET/MRI 患者研究中的结果。
