MRI定位对乳腺癌保乳术后部分乳腺照射的靶区和剂量的影响  

Comparison of MRI and CT for target volume delineation and dose coverage for partial breast irradiation in patients with breast cancer

作　　者：宋玉春 谢欣 车树楠 孙广毅 唐玉 张江鹄 王健仰 房辉 陈波 宋永文 金晶 刘跃平 亓姝楠 唐源 卢宁宁 景灏 杨勇 李宁 李静 王淑莲 李晔雄 Song Yuchun;Xie Xin;Che Shunan;Sun Guangyi;Tang Yu;Zhang Jianghu;Wang Jianyang;Fang Hui;Chen Bo;Song Yongwen;Jin Jing;Liu Yueping;Qi Shunan;Tang Yuan;Lu Ningning;Jing Hao;Yang Yong;Li Ning;Li Jing;Wang Shulian;Li Yexiong(Department of Radiation Oncology,National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing 100021,China;Department of Diagnostic Imaging,National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing 100021,China)

机构地区：[1]国家癌症中心/国家肿瘤临床医学研究中心/中国医学科学院北京协和医学院肿瘤医院放疗科,100021 [2]国家癌症中心/国家肿瘤临床医学研究中心/中国医学科学院北京协和医学院肿瘤医院影像诊断科,100021

出　　处：《中华放射肿瘤学杂志》2021年第3期244-248,共5页Chinese Journal of Radiation Oncology

基　　金：国家重点研发计划项目(2016YFC0904600);首都临床特色应用研究(Z171100001017116)。

摘　　要：目的比较乳腺癌保乳术后仰卧位CT与MRI定位图像的靶区和剂量的差异,探讨MRI定位在保乳术后部分乳腺照射中的应用价值。方法29例早期乳腺癌患者保乳术后放疗前在仰卧位下行CT及MRI定位扫描,分别对CT与MRI图像上的瘤床进行术腔可视化评分(CVS),勾画瘤床(TB)、临床靶区(CTV)、计划靶区(PTV),并基于CT图像制定部分乳腺照射计划。比较CT与MRI图像上TB的CVS、靶区差异与一致性,探讨40 Gy处方剂量等剂量线覆盖PTV比例差异。结果CT、MRI图像上TB的CVS分别为2.97±1.40、3.10±1.40(P=0.408)。MRI图像上勾画的TB、CTV、PTV较CT均明显增加,分别为(24.48±16.60)cm^(3)∶(38.00±19.77)cm^(3)、(126.76±56.81)cm^(3)∶(168.42±70.54)cm^(3)、(216.63±81.99)cm^(3)∶(279.24±101.55)cm^(3)(均P<0.001),但CTV、PTV增加的比例较TB明显减小(均P<0.001)。CT与MRI图像勾画的TB、CTV、PTV一致性指数分别为0.43±0.13、0.66±0.11、0.70±0.09(P<0.001)。放疗计划40 Gy等剂量线覆盖PTV-CT与PTV-MRI比例中位数分别为95.6%(95.0%~97.5%)与81.9%(62.3%~92.4%)(P<0.001)。结论CT与MRI对于TB术腔的可视化相近,但MRI图像勾画的TB、CTV、PTV范围明显增加,基于CT图像制定的放疗计划对于PTV-MRI剂量覆盖不充分。作为CT定位的补充,保乳术后MRI定位的应用可能可以提高TB勾画的准确性。Objective To compare magnetic resonance imaging(MRI)-based and computed tomography(CT)-based target volume delineation and dose coverage in partial breast irradiation(PBI)for patients with breast cancer,aiming to explore the application value of MRI localization in PBI after breast-conserving surgery.Methods Twenty-nine patients with early breast cancer underwent simulating CT and MRI scans in a supine position.The cavity visualization score(CVS)of tumor bed(TB)was evaluated.The TB,clinical target volume(CTV),planning target volume(PTV)were delineated on CT and MRI images,and then statistically compared.Conformity indices(CI)between CT-and MRI-defined target volumes were calculated.PBI treatment plan of 40 Gy in 10 fractions was designed based on PTV-CT,and the dose coverage for PTV-MRI was evaluated.Results The CVS on CT and MRI images was 2.97±1.40 vs.3.10±1.40(P=0.408).The volumes of TB,CTV,PTV on MRI were significantly larger than those on CT,(24.48±16.60)cm^(3)vs.(38.00±19.77)cm^(3),(126.76±56.81)cm^(3)vs.(168.42±70.54)cm^(3),(216.63±81.99)cm^(3)vs.(279.24±101.55)cm^(3),respectively,whereas the increasing percentage of CTV and PTV were significantly smaller than those of TB.The CI between CT-based and MRI-based TB,CTV,PTV were 0.43±0.13,0.66±0.11,0.70±0.09(P<0.001),respectively.The median percentage of PTV-MRI receiving 40 Gy dose was 81.9%(62.3%to 92.4%),significantly lower than 95.6%(95.0%~97.5%)of PTV-CT.Conclusions The CVS between CT and MRI is not significantly different,but the MRI-based TB,CTV,PTV are significantly larger than CT-based values.The PTV-MRI is of underdose if PBI treatment plan is designed for PTV-CT.As a supplement of CT scan,MRI can enhance the accuracy of TB delineation after breast-onserving surgery.

关 键 词：乳腺肿瘤/术后放射疗法 乳腺肿瘤/部分乳腺照射 磁共振定位 靶区勾画 

分 类 号：R737.9[医药卫生—肿瘤]