CT评价胸腔积液量准确性的实验研究

目的评价CT测算胸腔积液量的准确性。方法采用GE—sytec 4000i全身CT扫描系统，对注水肺脏模型进行扫描。选取右侧肺脏共作15次测量。由一名熟练的CT操作人员在积液最明显的一层上用轨迹手工圈划出积液的完整轮廓，预设感兴趣区的CT值上下限范围0-20 HU，采用计算机体积测算功能，计算出各层满足上述要求的感兴趣区图像总体积。结果肺脏模型体积CT测值与实际注水量的散点图呈直线趋势，R^2=1.000。回归系数t检验的t值=681、077，P=0．0001（P〈0.001），可认为肺脏模型体积CT测值与实际注水量之间有直线关系；直线回归方程为：Y=-0．238＋0．999X。肺脏模型体积的标准差为893．27504，实际注水量的标准差为894．42719。肺脏模型体积CT测值与实际注水量的相关分析表明，肺脏模型体积CT测值与实际注水量高度相关（P〈0．001）。结论CT能够准确测量胸腔积液量，它有可能替代传统X线的粗略估算。

Experimental study on quantification accuracy of pleural effusions with CT

Objective To evaluate the accuracy of CT scans in the quantification of pleural effusion.Methods The measurements of pleural effusions were performed on a lung model filed with water by using GE-sytec 4000i CT scanner,which were totally measured 15 times on selected right lung.First,one experienced radiologist describe the complete outline of pleural effusions on most obvious layer and predetermine the CT value range of the interested area with 0 to 20 HU,second,calculate the whole volume of each layer interested area by using volumetry function of computer.Results The scatter plot between the CT measurements of lung model volume and the samples of real filed water presented as a linear relationship（R^2=1.000）,the regressive coefficient value t equals 681,077,and p=0.0001 （p 〈 0.001）,so that the CT measurements of lung model volume and real filed water were linear correlation, the equation is Y=-0.238＋ 0.999X.The standard deviation of lung madel volume equals 893.27504, while that of real filed water equals 894.42719.The correlative analysis of above both suggested that the both were highly correlated（P〈0.001）.Condusion CT can accurately measure the pleural effusion on lung model and it is possible to replace the cursory estimation from traditional X-ray.