Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Department of Radiological Technology, Kumamoto University Hospital, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
Jpn J Radiol. 2020 Mar;38(3):256-264. doi: 10.1007/s11604-019-00911-6. Epub 2019 Dec 13.
This observer study aimed to compare rigid image registration (RIR) with deformable image registration (DIR) for diagnostic position (DP) positron emission tomography/computed tomography (PET/CT) images in the delineation of gross tumor volumes (GTVs) in nasopharyngeal carcinoma (NPC) radiotherapy planning.
Four radiation oncologists individually delineated the GTVs, GTV, and GTV, on planning CT (pCT) images registered with DP-PET/CT images using RIR and B-spline-based DIR, respectively. Reference GTVs were independently delineated by all radiation oncologists using radiotherapy position (RP)-PET/CT images. DP- and RP-PET/CT images for 14 patients with NPC were acquired using early and delayed scans, respectively. Dice's similarity coefficient (DSC), mean distance to agreement, and volume agreement with reference GTVs were compared by considering the interobserver variability in reference contours.
The average DSCs for GTV and GTV were 0.77 and 0.77, which were acceptable for GTV delineation. There were no statistically significant differences between GTV and GTV in all evaluation indexes (p > 0.05). Furthermore, the correlation between neck flexion angle differences and GTV accuracy was not statistically significant (p > 0.05).
RIR was a feasible choice compared with the B-spline-based DIR in GTV delineation for NPC under variations of neck flexion angle.
本观察性研究旨在比较刚性图像配准（RIR）与变形图像配准（DIR）在诊断位置（DP）正电子发射断层扫描/计算机断层扫描（PET/CT）图像在鼻咽癌（NPC）放射治疗计划中勾画大体肿瘤体积（GTV）的应用。
4 位放射肿瘤学家分别使用 RIR 和基于 B 样条的 DIR 将 DP-PET/CT 图像与计划 CT（pCT）图像配准，在 pCT 图像上勾画 GTV、GTV 和 GTV。所有放射肿瘤学家均使用放疗位置（RP）-PET/CT 图像独立勾画参考 GTV。14 例 NPC 患者分别采用早期和延迟扫描采集 DP 和 RP-PET/CT 图像。考虑参考轮廓的观察者间变异性，比较 Dice 相似性系数（DSC）、平均符合距离和与参考 GTV 的体积符合度。
GTV 和 GTV 的平均 DSC 分别为 0.77 和 0.77，可接受用于 GTV 勾画。在所有评价指标中，GTV 和 GTV 之间无统计学差异（p＞0.05）。此外，颈部弯曲角度差异与 GTV 准确性之间的相关性无统计学意义（p＞0.05）。
与基于 B 样条的 DIR 相比，在颈部弯曲角度变化时，RIR 是 NPC 中 GTV 勾画的可行选择。
