Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
J Nucl Med. 2011 May;52(5):712-9. doi: 10.2967/jnumed.110.086678. Epub 2011 Apr 15.
Phantom studies have shown improved lesion detection performance with time-of-flight (TOF) PET. In this study, we evaluate the benefit of fully 3-dimensional, TOF PET in clinical whole-body oncology using human observers to localize and detect lesions in realistic patient anatomic backgrounds. Our hypothesis is that with TOF imaging we achieve improved lesion detection and localization for clinically challenging tasks, with a bigger impact in large patients.
One hundred patient studies with normal (18)F-FDG uptake were chosen. Spheres (diameter, 10 mm) were imaged in air at variable locations in the scanner field of view corresponding to lung and liver locations within each patient. Sphere data were corrected for attenuation and merged with patient data to produce fused list-mode data files with lesions added to normal-uptake scans. All list files were reconstructed with full corrections and with or without the TOF kernel using a list-mode iterative algorithm. The images were presented to readers to localize and report the presence or absence of a lesion and their confidence level. The interpretation results were then analyzed to calculate the probability of correct localization and detection, and the area under the localized receiver operating characteristic (LROC) curve. The results were analyzed as a function of scan time per bed position, patient body mass index (BMI < 26 and BMI ≥ 26), and type of imaging (TOF and non-TOF).
Our results showed that longer scan times led to an improved area under the LROC curve for all patient sizes. With TOF imaging, there was a bigger increase in the area under the LROC curve for larger patients (BMI ≥ 26). Finally, we saw smaller differences in the area under the LROC curve for large and small patients when longer scan times were combined with TOF imaging.
A combination of longer scan time (3 min in this study) and TOF imaging provides the best performance for imaging large patients or a low-uptake lesion in small or large patients. This imaging protocol also provides similar performance for all patient sizes for lesions in the same organ type with similar relative uptake, indicating an ability to provide a uniform clinical diagnosis in most oncologic lesion detection tasks.
在本研究中，我们使用人体观察者来评估完全 3 维、TOF PET 在临床全身肿瘤学中的益处，以在现实患者解剖背景下定位和检测病变。我们的假设是，使用 TOF 成像，我们可以实现对临床挑战性任务的改善的病变检测和定位，对于大患者的影响更大。
选择了 100 例有正常（18）F-FDG 摄取的患者研究。在空气（直径 10mm）中成像，位置对应于每个患者内的肺和肝位置的扫描仪视野中的位置。将球体数据校正衰减并与患者数据合并，以生成添加了正常摄取扫描的融合列表模式数据文件。使用列表模式迭代算法，使用或不使用 TOF 核，对所有列表文件进行完全校正和重建。将图像呈现给读者，以定位和报告病变的存在或不存在及其置信水平。然后分析解释结果，以计算正确定位和检测的概率以及定位的局部接收器操作特性（LROC）曲线下面积。结果按床位位置的扫描时间、患者体重指数（BMI<26 和 BMI≥26）和成像类型（TOF 和非 TOF）进行分析。
我们的结果表明，所有患者大小的 LROC 曲线下面积随着扫描时间的延长而提高。使用 TOF 成像时，对于较大的患者（BMI≥26），LROC 曲线下面积的增加更大。最后，当结合较长的扫描时间和 TOF 成像时，我们看到较大和较小患者的 LROC 曲线下面积之间的差异较小。
较长的扫描时间（本研究中为 3 分钟）和 TOF 成像的组合为成像大患者或小或大患者中的低摄取病变提供了最佳性能。对于相同器官类型的具有相似相对摄取的病变，该成像方案也为所有患者大小提供了相似的性能，这表明在大多数肿瘤病变检测任务中都有能力提供统一的临床诊断。
