The Research Of Surface Measurement To Calculate Chest Volume Of Pectus Excavatum Rats

Objective: To calculate the chest volume for an evaluation of lung development, the degree of thorax narrowing and pectus excavatum deformity by the surface measurements.Methods: 90 normal Sprague-Dawley(4 weeks) rats were randomly divided into experimental and control groups.Experimental group were 70 and control group were 20.Cutting off the lower three cartilage from parasternal of rats to produce Pectus excavatum model in experimental groups.Measuring many chest radial lines before surgery,2 weeks,4 weeks,8 weeks,12 weeks after surgery respectively,then making comparison between parallel group.Thoracic volume size is calculated by a mathematical formula, Archimedes measurement and three-dimensional reconstruction of CT scan,for t-test and linear regression analysis by SPSS17.0.Results: The anteroposterior diameter of connecting plane of Sternum xiphoid in experimental groups of rats less than the control group at various time,a statistically significant difference between the two(P <0.001),only the diameter less than the co s time pointsntrol group at 4 weeks after surgery(P<0.05),thoracic length is only decreased at 8 weeks after surgery(P<0.05),the rest of the diameter line between the two groups showed no abnormalities(P>0.05);The chest volume resulting by mathematical calculation more than the resulting by Archimedes measurement and CT three-dimensional reconstruction at each observation time point between two groups of rats;The chest volume resulting by mathematical calculation of the experimental group of rats were less than the control group at 4 week after surgery(8.24±0.93 V 9.56±0.92cm3,P<0.05),the results have significant difference was observed to 12 weeks after surgery between the two groups(15.70±1.26 V 18.76±0.82 cm3,P<0.001);Experiments using measurement results of Chest volume to compare,through mathematical calculations,Archimedes measurement, three-dimensional reconstructions of CT scan.The Chest volume by mathematical calculations were significantly correlated with the Archimdes measurement and CT-based pulmonary volumetric within the experimental groups,the correlation coefficients are 0.952 and 0.918.And these correlations in normal rats who behave more pronounced(0.969 and 0.981).Conclusion: The change of the anteroposterior diameter of the sternum xiphoid junction is the most obvious along the process of PE formation.It is practicable about surface measurement to bulid mathematical model to calculate chest volume.This method can replace the CT examination to evaluate the change of the chest volume along the process of pectus excavatum formation.