Gordon Center for Medical Imaging, Radiology Department, Massachusetts General Hospital - Harvard Medical School, 125 Nashua St., 25 Shattuck St., Boston, MA 02114, USA.
Yale PET Center, Dept. of Radiology and Biomedical Imaging, Yale University, 801 Howard Avenue, New Haven, CT 06520, USA.
Radiother Oncol. 2024 May;194:110186. doi: 10.1016/j.radonc.2024.110186. Epub 2024 Feb 25.
Accurate gross tumor volume (GTV) delineation is a critical step in radiation therapy treatment planning. However, it is reader dependent and thus susceptible to intra- and inter-reader variability. GTV delineation of soft tissue sarcoma (STS) often relies on CT and MR images.
This study investigates the potential role of F-FDG PET in reducing intra- and inter-reader variability thereby improving reproducibility of GTV delineation in STS, without incurring additional costs or radiation exposure.
Three readers performed independent GTV delineation of 61 patients with STS using first CT and MR followed by CT, MR, and F-FDG PET images. Each reader performed a total of six delineation trials, three trials per imaging modality group. Dice Similarity Coefficient (DSC) score and Hausdorff distance (HD) were used to assess both intra- and inter-reader variability using generated simultaneous truth and performance level estimation (STAPLE) GTVs as ground truth. Statistical analysis was performed using a Wilcoxon signed-ranked test.
There was a statistically significant decrease in both intra- and inter-reader variability in GTV delineation using CT, MR F-FDG PET images vs. CT and MR images. This was translated by an increase in the DSC score and a decrease in the HD for GTVs drawn from CT, MR and F-FDG PET images vs. GTVs drawn from CT and MR for all readers and across all three trials.
Incorporation of F-FDG PET into CT and MR images decreased intra- and inter-reader variability and subsequently increased reproducibility of GTV delineation in STS.
准确勾画肿瘤靶区（GTV）是放射治疗计划制定的关键步骤。然而，它依赖于读者，因此容易受到读者内和读者间的变异性的影响。软组织肉瘤（STS）的 GTV 勾画通常依赖于 CT 和 MRI 图像。
本研究旨在探讨 F-FDG PET 在降低 STS 中 GTV 勾画的读者内和读者间变异性方面的潜在作用，从而提高 GTV 勾画的可重复性，同时不增加额外的成本或辐射暴露。
三位读者使用 CT 和 MRI 首次进行 GTV 勾画，然后使用 CT、MR 和 F-FDG PET 图像进行 GTV 勾画。每位读者共进行了六次勾画试验，每种成像方式组各进行三次试验。使用生成的同时真实和性能水平估计（STAPLE）GTV 作为金标准，使用 Dice 相似系数（DSC）评分和 Hausdorff 距离（HD）评估读者内和读者间的变异性。使用 Wilcoxon 符号秩检验进行统计分析。
与 CT 和 MR 图像相比，使用 CT、MR 和 F-FDG PET 图像进行 GTV 勾画时，读者内和读者间的变异性均有统计学显著降低。这表现为 DSC 评分增加，HD 降低，所有读者和所有三次试验中，从 CT、MR 和 F-FDG PET 图像勾画的 GTV 与从 CT 和 MR 图像勾画的 GTV 相比。
将 F-FDG PET 纳入 CT 和 MR 图像中，降低了 STS 中 GTV 勾画的读者内和读者间变异性，从而提高了 GTV 勾画的可重复性。
