建立基于CT影像的胆囊体积计算方法及其运动功能分析

Establishment of Gallbladder Volume Calculation Method and Analysis of Motor Function Based on CT Images

目的评价基于CT影像三维重建胆囊体积计算方法的准确性,并研究胆囊运动中的生物力学变化,探索胆囊动力学变化与胆结石形成的关系。方法提出一种基于CT影像三维重建胆囊模型来计算胆囊体积的方法,并与椭球体法进行比较;构建胆囊有限元模型并进行流体力学分析,模拟胆囊出口胆囊管与胆总管汇合不同角度下及伴有结石状态下的胆囊运动功能变化。结果比较50位患者的特异性胆囊模型体积和椭球体法体积,对应平均误差分别为7.26%和25.35%。梨形胆囊再充盈期最大压力、最大变形和最大流速都明显大于葫芦形胆囊。胆囊管与胆总管之间的夹角对胆汁流型影响不大,夹角为120°时胆汁流速最大。伴有结石胆囊的胆汁流速小于无结石胆囊,且在结石附近产生漩涡。结论基于CT影像三维重建计算胆囊体积较传统椭球体法更准确。相对于梨形胆囊,葫芦形胆囊的胆囊壁收缩和胆汁流速较小,运动功能差。伴结石胆囊的胆汁流速较慢,更易导致结石增大或新结石形成。

Objective To evaluate the accuracy of three-dimensional(3D)reconstruction of the gallbladder volume based on computed tomography(CT)images and study the biomechanical changes in gallbladder motility to explore the relationship between gallbladder dynamics and gallstone formation.Methods A method for calculating gallbladder volume based on CT 3D reconstruction of The gallbladder model was proposed and compared with the ellipsoid method.A finite element model of the gallbladder was constructed for fluid dynamics analysis to simulate changes in gallbladder motor function under different angles of convergence between the cystic and common bile ducts and in the presence of gallstones.Results The mean errors of the specific gallbladder model volume and ellipsoid volume of the 50 patients were 7.26%and 25.35%,respectively.During the refilling period,the maximum pressure,deformation,and flow velocity of the pear-shaped gallbladder were significantly higher than those of the gourd-shaped gallbladder.The angle between the gallbladder and common bile duct had little effect on the bile flow pattern,and the maximum bile flow rate was reached at an angle of 120°.The bile flow velocity of the gallbladder with calculus was lower than that of the gallbladder without calculus,and there was a vortex near the calculus.Conclusions Calculating gallbladder volume based on CT 3D reconstruction is more accurate than the ellipsoid method.Compared with a pear-shaped gallbladder,a gourd-shaped gallbladder has lower gallbladder wall contraction,bile flow rate,and poor motor function.The bile flow rate in the gallbladder is slow,which is more likely to lead to the enlargement of gallstones or the formation of new gallstones.