Department of Radiology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and.
J Nucl Med. 2014 Apr;55(4):602-7. doi: 10.2967/jnumed.113.127035. Epub 2014 Mar 6.
Inclusion of time-of-flight (TOF) information in PET reconstructions has been demonstrated to improve image quality through better signal-to-noise ratios, faster convergence, better lesion detectability, and better image uniformity. The goal of this work was to assess the impact of TOF information on the accuracy and precision of quantitative measurements of activity uptake in small lesions in clinical studies.
Data from small (10-mm diameter) spheres were merged with list-mode data from 6 healthy volunteers after injection of (18)F-FDG. Six spheres having known activity uptake with respect to the average whole-body uptake were embedded in both the liver and the lung of the subject's data. Images were reconstructed with TOF information and without TOF information (non-TOF reconstruction). The measured uptake was compared with the known activity; variability was measured across 60 bootstrapped replicates of the merged data, across the 6 spheres within a given organ, and across all spheres in all subjects.
The average uptake across all spheres and subjects was approximately 50% higher in the lung and 20% higher in the liver with TOF reconstruction than with non-TOF reconstruction at comparable noise levels. The variabilities across replicates, across spheres within an organ, and across all spheres and subjects were 20%-30% lower with TOF reconstruction than with non-TOF reconstruction in the lung; in the liver, the variabilities were 10%-20% lower with TOF reconstruction than with non-TOF reconstruction.
TOF reconstruction leads to more accurate and precise measurements, both within a subject and across subjects, of the activity in small lesions under clinical conditions.
在 PET 重建中加入飞行时间 (TOF) 信息已被证明可以通过提高信噪比、更快的收敛速度、更好的病灶检测能力和更好的图像均匀性来改善图像质量。这项工作的目的是评估 TOF 信息对临床研究中小病灶活性摄取定量测量的准确性和精度的影响。
在向 6 名健康志愿者注射 (18)F-FDG 后，将小（直径 10 毫米）球体的数据与列表模式数据合并。将 6 个具有相对于全身摄取的已知活性摄取的球体嵌入受试者数据的肝脏和肺部。使用 TOF 信息和无 TOF 信息（非 TOF 重建）重建图像。将测量的摄取与已知的活性进行比较；在合并数据的 60 个引导重复中、在给定器官内的 6 个球体之间以及在所有受试者中的所有球体之间测量变异性。
在可比噪声水平下，与非 TOF 重建相比，TOF 重建使所有球体和受试者的平均摄取在肺部增加约 50%，在肝脏增加约 20%。在肺部，与非 TOF 重建相比，TOF 重建的重复性、器官内球体之间以及所有球体和受试者之间的变异性降低 20%-30%；在肝脏中，TOF 重建的变异性比非 TOF 重建降低 10%-20%。
在临床条件下，TOF 重建可实现对小病灶活性的更准确和更精确的测量，无论是在一个受试者内还是在多个受试者之间。
