Liu Chengxin, Kong Xudong, Gong Guanzhong, Liu Tonghai, Li Baosheng, Yin Yong
Department of Radiation Oncology, Shandong's Key Laboratory of Radiation Oncology, Shandong Cancer Hospital, School of Medicine and Life Sciences, University of Jinan and Shandong Academy of Medical Sciences, JiYan Road 440, Jinan, 250117, Shandong, China.
Jpn J Radiol. 2014 Apr;32(4):211-6. doi: 10.1007/s11604-014-0286-0. Epub 2014 Feb 21.
To analyze the intra- and interobserver variations errors in the parotid contour delineated using computed tomography (CT) or magnetic resonance (MR) images of patients with nasopharyngeal carcinoma who underwent radiotherapy.
Forty-one nasopharyngeal cancer patients were selected. The patients underwent simulation with MR and CT scanning. The gross tumor volume and organs at risk were contoured on both contrasted CT and T1-MR images. For each patient, one radiotherapist delineated the parotid on CT and MR images ten times, and ten different radiotherapists were asked to delineate the parotid on CT and MR images once each. The inter- and intraobserver variations in volume and outline were compared.
For the interobserver comparison, the volumes of the parotid as evaluated from the CT and MR images were 34.6 ± 12.1 cm(3) (left), 34.3 ± 9.0 cm(3) (right), and 24.6 ± 7.6 cm(3) (L), 23.2 ± 8.1 cm(3) (R), respectively. For the intraobserver comparison, the volumes evaluated from the CT and MR images were 28.2 ± 7.6 cm(3) (L), 29.4 ± 9.4 cm(3) (R), and 24.4 ± 7.6 cm(3) (L), 22.5 ± 7.4 cm(3) (R), respectively. The relative variations in volume when using MR images were 4.7 ± 0.7 % (L), 5.0 ± 0.6 % (R) for the interobserver variations and 2.3 ± 0.4 % (L), 2.1 ± 0.7 % (R) for the intraobserver variations. However, the inter- and intraobserver relative variations in volume when using CT images were 18.0 ± 4.8 % (L), 17.4 ± 4.6 % (R) and 6.3 ± 1.5 % (L), 6.8 ± 1.5 % (R), respectively.
The parotid contour is delineated more accurately and reproducibly on MR images than on CT images.
分析鼻咽癌放疗患者使用计算机断层扫描（CT）或磁共振（MR）图像勾画腮腺轮廓时观察者间和观察者内的变异误差。
选取41例鼻咽癌患者。患者接受MR和CT扫描模拟。在增强CT和T1-MR图像上勾画大体肿瘤体积和危及器官。对于每位患者，一名放射治疗师在CT和MR图像上对腮腺进行十次勾画，另外十名不同的放射治疗师分别在CT和MR图像上对腮腺进行一次勾画。比较观察者间和观察者内体积及轮廓的变异。
观察者间比较时，从CT和MR图像评估的腮腺体积分别为左34.6±12.1 cm³、右34.3±9.0 cm³，以及左24.6±7.6 cm³、右23.2±8.1 cm³。观察者内比较时，从CT和MR图像评估的腮腺体积分别为左28.2±7.6 cm³、右29.4±9.4 cm³，以及左24.4±7.6 cm³、右22.5±7.4 cm³。使用MR图像时，观察者间体积相对变异为左4.7±0.7%、右5.0±0.6%，观察者内体积相对变异为左2.3±0.4%、右2.1±0.7%。然而，使用CT图像时，观察者间和观察者内体积相对变异分别为左18.0±4.8%、右17.4±4.6%，以及左6.3±1.5%、右6.8±1.5%。
与CT图像相比，MR图像能更准确且可重复地勾画腮腺轮廓。
