Primary Application Of Quantitative Study Of Pleural Effusion By Computed Tomography Combined With Computer Aided Geometuic Design Technology

Pleural effusion is a common clinical problem that has many potential causes. The quantity of pleural effusion is often necessary because it plays an important role in providing a reliable evidence for clinical treatment and making therapeutic plan and evaluating the prognosis. Estimating the volume of pleural effusion usually depends on imaging methods. When estimating the size of pleural effusions, chest radiograph or ultrasound are usually used. Chest radiography examination is of a rough estimate which can fail to detect small effusions such as 200 ml of fluid even when decubitus views are included. We may roughly judge the amount of pleural fluid exceeds 300 ml or 400 ml when the costophrenic angle becomes blunt or disappear. This method is lack of quantitative index, only rough judges for a small, medium or a large amount of pleural fluid. Ultrasonogmaphy (US) will detect the presence of small amount of pleural fluid and is sensitive for effusions of less than 100 ml. Ultrasonography has particular value for the assessment and safe drainage of pleural . But it also lack of quantitative index and can not accurately estimate the fluid volume. At present computed tomography is more sensitive than both conventional chest radiography and US for differentiating pleural fluid from pleural thickening and for the identification of focal masses involving the pleura or the chest wall. Its image displayed on pleural effusion is more accurate and intuitive. Compared with chest radiography, CT can easily distinguish mass, nodules, pleural plaques, calcification and the extent and location of encapsulated pleural effusion. But so far there are fewer literature on the chest CT quantitative study of pleural effusion. The purpose of this article is to study the primary application of the quantity of pleural effusion by computed tomography combined with computer Aided Design technology for providing more reliable evidence on making clinical treatment plan and evaluating the prognosis.OBJERCTIVE:To investigate the primary application of using computed tomography combined with computer Aided Design technology to determine the quantity of pleural effusion.METHODS: Twenty cases were enrolled into our study. All the patients had no chest deformity and mediastinal lesions, and the exclusion of pneumothorax or serious separated fibrous effusion. Thoracocentesis was preformed with twenty patients and be taken away a certain amount (that is, the actual volume of pleural effusion). Chest CT scanning were preformed before and six hours after the thoracocentesis. Then we found out characteristic dots on the outline of chest wall and pleural effusion by region growing imaging Segmentation. Described the outline of the chest wall and fluid by using cubic Hermite interpolation method and calculated the pixels within the contours. The volume of pleural effusion were obtained when the pixels is converted into voxels. All the results tested were paired t-test.RESULTS:1. There were not statistically differences between the theoretical prediction of fluid volume calculated by software and the actual volume (1002.15±401.44 vs 992.50±410.18 ) (P> 0.05) .2. Scatter diagrams shows that the actual volume of pleural effusion and theoretical prediction are highly linear relationship (r = 0.997, p <0.001) .3. There were good agreements between the actual volume of pleural effusion and theoretical prediction by Bland-Altman analysis. CONCLUSION :Combination with computed tomography and computer aided geometric design technology can accurately calculate fluid volume, thus it plays an important role in making therapeutic plan and evaluating the prognosis.