摘要目的 探讨基于四维CT (4DCT)测定的胸中下段食管癌原发大体肿瘤体积(GTV)位移与邻近器官位移相关性及呼吸周期中GTV与心脏、肺体积变化相关性.方法 17例胸中下段食管癌患者自由呼吸状态下行4DCT模拟定位扫描,通过图像配准获取同一坐标系下10个呼吸时相图像.在配准图像上分别勾画GTV、邻近器官(肺、心脏、膈肌顶),获取各呼吸时相中GⅣ与邻近器官三维坐标和体积.用配对t检验比较GTV中心点在左右(x轴)、前后(y轴)、头脚(z轴)方向的最大位移,用Pearson法分析GTV与邻近器官位移、GTV与心肺体积相关性.结果 GTV中心点在x、y、z轴方向的最大位移平均值分别为0.19、0.17、0.48 cm,z与x、y轴方向位移差异有统计学意义(t=-3.59、-4.09,P=0.002、0.001).GTV位移与右肺x、y、z轴均相关(r=0.922、0.700、0.994,P=0.000、0.024、0.000),与心脏x、y、z轴也均相关(r=0.720、0.920、0.910,P=0.010、0.000、0.000),与左肺z轴相关(r =0.987,P=0.000),与左右膈肌顶z轴相关(r=0.918、0.928,P=0.000、0.000).呼吸周期中GTV变化与双肺体积变化均呈负相关(r-0.680、-0.067,P=0.031、0.034),与心脏体积变化无关(r=-0.368,P=0.295).结论 平静呼吸下胸中下段食管癌GTV的z轴位移最大且与双侧膈肌顶位移同步,呼吸周期中GTV与双肺及心脏体积变化相关性不同.

abstractsObjective To investigate the correlation between the motion of gross tumor volume (GTV) and the interested organs, and the correlation between the volume of GTV and the volume of heart and lung for the mid - and distal esophageal cancer using four - dimensional CT ( 4 DCT ) . Methods Seventeen patients with middle/distal esophageal carcinoma underwent respiration-synchronized 4DCT simulation during free breathing. All image sets were registered with the reference image ( T0 phase) , and the GTV, the dome of diaphragm, lung and heart were delineated on CT images of the ten respiratory phases. The position of GTV, lung, heart and the dome of diaphragm were identified in all 4DCT phases,and the volume of GTV , lung and heart were also achieved. Paired sample t test wereperformed to compare the primary esophageal cancer displacement in the three directions. The pearson correlation test was use to study the corTelation of GTV motion with the OARs , and the volume correlation of GTV with lung and heart.Results The maximum displacement of the GTV were 0. 19 cm,0. 17 cm,and 0. 48cm , respectively in x,y and z directions. And the displacement were significant different between z and x, y directions (t = - 3. 59 , - 4. 09 ,P = 0. 002,0.001) . The displacement of GTV correlated well with right lung and heart in three dimensions ( TRL-x = 0. 922 ,PRL-x = 0. 000 , TRL-y = 0. 700 , PRL-y = 0. 024, rRL-z = 0. 994 , PrRL-z = 0. 000;TH-x = 0. 720 , PH-x = 0. 010, rH-y = 0. 920 , PH-y = 0. 000 , rH-z = 0. 910, PH-z = 0. 000 ) , and only significantly associated with left lung in z direction (r = 0. 987,P = 0. 000) . There was a good correlation between GTV and the dome of diaphragm in z direction ( rL = 0. 918 , PL = 0. 000 ; rR= 0. 928 , PR= 0. 000 ) . Changes in the GTV volume was correlated well with the lung volume ( rLL = - 0. 680, PLL =0. 031 ;rrL = - 0. 670, PrL = 0. 034) , but the correlation was not significant with the heart ( r= -0. 368, P= 0. 295 ) during respiratory cycle. Conclusions For middle/distal esophageal cancer, the primary tumor motion was maximal in superior-inferior direction during normal respiration, and synchronized with the dome of diaphragm. The primary tumor displacement and volume variation have different correlations with heart and lung.