3D Reconstruction Of Cerebrovascular Point Cloud And Its Hemodynamic Analysis

As of 2015,the prevalence of cerebrovascular diseases is as high as 15%,which has seriously threatened the health and cerebrovascular three-dimensional visualization and numerical simulation of Chinese residents and provided important diagnostic and therapeutic information for researchers and clinicians.Point cloud data processing is the current research focus,has been used in VR,autopilot and other new technologies,this article will be applied to the field of cerebrovascular.Some undifferentiated vascular point cloud data,it is difficult to get high-quality cerebral vascular model and the next blood flow analysis,this article intended to have a complex topology of cerebrovascular segmentation,skeleton line extraction,smooth surface reconstruction and blood flow Kinetic analysis to study.For the segmentation of cerebrovascular point cloud data,a segmentation method based on connectivity is proposed.The segmentation algorithm based on connectivity establishes the coverage set,analyzes the characteristics of the coverage set,formulates the judgment criteria of the coverage set connectivity,and then determines the starting point of segmentation,and expands the point set by judging the connectivity of the coverage set.When the heuristic set is disconnected Then there may be bifurcation region.In this case,we need to reversely expand the root to optimize the judgment.Finally,the unprocessed coverage set continues to be expanded until all the coverage sets are processed to complete the local segmentation of cerebrovascular.On the basis of segmentation,a skeleton extraction method based on spatial median is proposed.Based on the method of spatial median,the local radius is introduced to introduce the repulsive force and the density weight function to extract the skeleton points.Then the extracted skeleton points are connected into lines,and the skeletons at the branches are connected and bifurcated Skeletal line connection presents a solution.Finally,this thesis completes the extraction of cerebral vascular skeleton points and the connection of skeleton lines.Cerebral vascular surface reconstruction is based on the skeleton line.First,we stratified coding of the skeleton line and reorganized into each single branch.And then through the adjacent equally spaced sampling skeleton points calculate the tangent vector and the optimal section cross-sectional diameter,orthogonal cross-section circle,the outline of the points on the triangle Then the Delaunay triangulation method is proposed to deal with the surface of the bifurcation area.The Delaunay-like Delaunay triangulation is constructed by mapping the "eating each other" between the branches to the two-dimensional plane,and then the surface of the bifurcation area is spliced.Finally,the surface of the reconstructed surface is subdivided into Loop segments to obtain a smooth and accurate three-dimensional surface model of cerebrovascular.From the three-dimensional modeling of cerebral blood vessels to get the relevant vascular shape and geometric parameters of hemodynamic study is essential to help clinical research and diagnosis of cerebrovascular disease.A cardiac cycle was numerically simulated by meshing blood flow parameters and setting the relevant boundary conditions in the local cerebrovascular region of interest and the stenosis,and the effects of different time points under normal conditions and at narrow time Blood flow velocity,wall pressure and wall shear stress three dynamic parameters.