Jin Meng, Liu Xia, Ma Jiabin, Sun Xiansong, Zhen Hongnan, Shen Jing, Liu Zhikai, Lian Xin, Miao Zheng, Hu Ke, Hou Xiaorong, Zhang Fuquan
Department of Radiation Oncology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China.
Department of Radiation Oncology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China.
Cancer Manag Res. 2021 Jul 12;13:5633-5640. doi: 10.2147/CMAR.S301705. eCollection 2021.
In the management of breast-conserving radiotherapy, computed tomography (CT) simulation is now commonly used to identify tumor bed while has difficulties defining precisely. We aimed to evaluate the impact of magnetic resonance (MR) and CT simulation on defining the postoperative tumor bed for breast-conserving radiotherapy in patients without the aid of surgical clips.
From August 2018 to March 2019, twenty patients with TNM breast cancer at our institution were enrolled. All the patients underwent breast-conserving surgery without implantation of surgical clips and were prepared to receive radiotherapy. CT and MR images were acquired on the same day for each patient. Three radiation oncologists independently assigned cavity visualization score (CVS) and delineated the tumor bed based on first the CT then the MR images. Interobserver variability was assessed by volumes, generalized conformity index (CI) and the distance between the centers of mass (dCOM). Differences in mean values for parameters were tested by paired -test or one-way analysis of variance, as appropriate.
First, the mean volumes of tumor bed derived from MR were 22%, 27% and 21% smaller than those based on CT images for each observer. In addition, the mean CI was significantly superior, and dCOM was smaller for MR than for CT images (CI: 0.59 vs 0.52, = 0.008; dCOM: 1.30 cm vs 1.39 cm, = 0.095). Moreover, the mean CVS was 3.23±1.34 and 2.43±0.92 for MR and CT images, respectively (= 0.035). Last, a positive association was observed between the CVS and CI for both modalities (< 0.01).
Compared to CT, MR can improve the visualization of changes in the postoperative tumor bed. In addition, MR can yield a more precise definition of the tumor bed and improve the consistency of tumor bed contouring in patients without surgical clips.
在保乳放疗管理中，计算机断层扫描（CT）模拟目前常用于识别瘤床，但难以精确界定。我们旨在评估磁共振（MR）和CT模拟在无手术夹辅助的情况下对保乳放疗术后瘤床界定的影响。
2018年8月至2019年3月，纳入我院20例TNM期乳腺癌患者。所有患者均接受了未植入手术夹的保乳手术，并准备接受放疗。为每位患者在同一天采集CT和MR图像。三名放射肿瘤学家独立分配腔可视化评分（CVS），并首先基于CT图像然后基于MR图像勾勒瘤床。通过体积、广义一致性指数（CI）和质心之间的距离（dCOM）评估观察者间的变异性。参数平均值的差异根据情况通过配对检验或单因素方差分析进行检验。
首先，每位观察者基于MR得出的瘤床平均体积比基于CT图像的瘤床平均体积分别小22%、27%和21%。此外，MR的平均CI显著更优，且MR的dCOM比CT图像更小（CI：0.59对0.52，P = 0.008；dCOM：1.30 cm对1.39 cm，P = 0.095）。而且，MR和CT图像的平均CVS分别为3.23±1.34和2.43±0.92（P = 0.035）。最后，两种模式下CVS与CI之间均观察到正相关（P < 0.01）。
与CT相比，MR可改善术后瘤床变化的可视化。此外，MR能更精确地界定瘤床，并提高无手术夹患者瘤床轮廓勾画的一致性。
