European Institute for Molecular Imaging, University of Münster, Mendelstraße 11, 48149, Münster, Germany.
Eur J Nucl Med Mol Imaging. 2010 Dec;37(12):2315-27. doi: 10.1007/s00259-010-1533-y. Epub 2010 Jul 6.
Respiratory motion of organs during PET scans is known to degrade PET image quality, potentially resulting in blurred images, attenuation artefacts and erroneous tracer quantification. List mode-based gating has been shown to reduce these pitfalls in cardiac PET. This study evaluates these intrinsic gating methods for tumour PET scans.
A total of 34 patients with liver or lung tumours (14 liver tumours and 27 lung tumours in all) underwent a 15-min single-bed list mode PET scan of the tumour region. Of these, 15 patients (8 liver and 11 lung tumours in total) were monitored by a video camera registering a marker on the patient's abdomen, thus capturing the respiratory motion for PET gating (video method). Further gating information was deduced by dividing the list mode stream into 200-ms frames, determining the number of coincidences (sensitivity method) and computing the axial centre of mass of the measured count rates in the same frames (centre of mass method). Additionally, these list mode-based methods were evaluated using only coincidences originating from the tumour region by segmenting the tumour in sinogram space (segmented sensitivity/centre of mass method). Measured displacement of the tumours between end-expiration and end-inspiration and the increase in apparent uptake in the gated images served as a measure for the exactness of gating. To estimate the accuracy, a thorax phantom study with moved activity sources simulating small tumours was also performed.
All methods resolved the respiratory motion with varying success. The best results were seen in the segmented centre of mass method, on average leading to larger displacements and uptake values than the other methods. The simple centre of mass method performed worse in terms of displacements due to activities moving into the field of view during the respiratory cycle. Both sensitivity- and video-based methods lead to similar results.
List mode-driven PET gating, especially the segmented centre of mass method, is feasible and accurate in PET scans of liver and lung tumours.
在 PET 扫描期间，器官的呼吸运动会降低 PET 图像质量，导致图像模糊、衰减伪影和示踪剂定量错误。基于列表模式的门控已被证明可以减少心脏 PET 中的这些缺陷。本研究评估了这些用于肿瘤 PET 扫描的固有门控方法。
共有 34 名肝或肺肿瘤患者（共 14 个肝肿瘤和 27 个肺肿瘤）接受了肿瘤区域 15 分钟的单次床列表模式 PET 扫描。其中，15 名患者（总共 8 个肝肿瘤和 11 个肺肿瘤）通过摄像机监测，摄像机记录患者腹部的标记物，从而为 PET 门控捕获呼吸运动（视频方法）。进一步的门控信息是通过将列表模式流分为 200 毫秒的帧来确定，确定符合数（灵敏度方法）和计算同一帧中测量计数率的轴向质心（质心法）来推断的。此外，通过在正弦图空间中分割肿瘤（分段灵敏度/质心法），仅使用来自肿瘤区域的符合来评估这些基于列表模式的方法。测量的肿瘤在呼气末期和吸气末期之间的位移以及门控图像中摄取的增加被用作门控精度的衡量标准。为了估计准确性，还进行了一项胸部体模研究，其中使用模拟小肿瘤的移动活性源。
所有方法都以不同的成功率解决了呼吸运动问题。分段质心法的结果最好，平均导致的位移和摄取值大于其他方法。由于在呼吸周期期间活动进入视场，简单质心法在位移方面表现较差。基于灵敏度和视频的方法产生相似的结果。
基于列表模式的 PET 门控，特别是分段质心法，在肝和肺肿瘤的 PET 扫描中是可行且准确的。
Zotero 插件