基于4DCT的腹部器官呼吸运动分析

背景与目的：个体化准确测量器官的呼吸移动度是确定腹部肿瘤体内边界（internal margin，IM）的前提。本研究应用4DCT（four-dimensional computed tomograpy）测量腹部器官在三维方向的呼吸移动度，并进一步分析膈肌与各器官移动度的关系。方法：选择13例肝癌患者行4DCT扫描，其中5例患者合并腹主动脉旁淋巴结转移。在10个呼吸时相的CT图像中分别勾画不同的器官，包括肝脏、双肾、胰腺、脾及腹主动脉旁淋巴结。在4DCT中测量膈肌及腹部各器官在三维方向的呼吸移动度，并分析膈肌移动度与各器官移动度是否相关。结果：膈肌在头尾方向的移动度为（10.3±4．0）mm，个体差异明显。肝、左右肾脏、胰腺、脾、腹主动脉旁淋巴结在头尾方向的移动度分别为（10．1±3．9）mm、（9．3±2．9）mm、（9．6±4．1）mm、（7．6±3．0）mm、（10．6±3．3）mm、（5．7±1．8）mm。肝脏、右肾的移动度与膈肌移动度无明显差异，且呈高度线性正相关关系；左肾、胰腺、脾的移动度与膈肌动度无明显相关；双侧肾脏的移动度相仿，但一侧肾脏的运动度并不能预测对侧肾脏的运动度。结论：应用4DCT可准确测量腹部器官在三维各方向的呼吸运动度。膈肌移动度可以代表肝脏和右肾头尾方向的运动度。而腹主动脉旁淋巴结的移动度相对较小。

Analysis of abdominal organ motion using four-dimensional CT

Background and Objective： Accurate individualized measurement of organ motion is the premise of defining internal margin （IM） for abdominal malignancies. This study was to assess the three-dimensional abdominal organ motion caused by respiration using four-dimensional computed tomography （4DCT）, and to analyze the association between the movement of diaphragm and abdominal organs. Methods： The 4DCT scans of 13 patients with hepatocellular carcinoma were analyzed, five of whom had para-aortic lymph node metastases. The liver, kidneys, pancreas, spleen, and para-aortic lymph nodes were contoured in all 10 respiratory phases of 4DCT scans. The 3D movement of diaphragm and organs was calculated and the relationship between the movement of diaphragm and abdominal organs was analyzed. Results： The average diaphragmatic movement was （10.3±4.0） mm with wide interpatient variations. Analysis of the center of the mass of abdominal organs revealed predominant cranio-caudal （CC） movement, with a mean of （10.1±3.9） mm for liver, （9.3±2.9） mm for left kidney, （9.6±4.1） mm for right kidney, （7.6±3.0） mm for pancreas, （10.6± 3.3） mm for spleen, and （5.7±1.8） mm for para-aortic lymph nodes. The CC movement of the liver and the right kidney correlated well with the diaphragmatic movement, and no significant differences were observed. There was no significant correlation of the diaphragmatic movement to the CC movement of left kidney, pancreas and spleen. The movement of both kidneys was comparable, however, the movement of one kidney did not predict the movement of the contralateral one. Conclusions： The 4DCT scanning can accurately measure abdominal organ motion during whole respiration. The diaphragmatic mobility can approximate the CC movement of liver and right kidney, and the movement amplitude of para-aortic lymph nodes is much smaller than diaphragmatic mobility.