基于方向Snake模型的心脏磁共振图像左心室内外膜分割

针对心脏磁共振图像(MRI)左心室内膜与外膜边缘方向不同的特点，提出一种基于曲线演化框架的方向主动轮廓模型进行左心室内外膜分割。曲线演化方程中包含基于图像边缘与区域灰度特征的混合几何流。几何流中的边缘信息项由经Fast Marching方法扩展后的动态方向梯度矢量流场（DDGVF）构成，用以引导曲线向具有不同方向的目标边缘运动，而区域灰度信息项则由Chan-Vese (CV)模型构成，用以防止曲线在演化过程中受其他边缘成分的影响而发生泄漏。最终的曲线演化方程采用水平集方法求解。实验结果表明，所提方法能够较为准确地分割出心脏MRI图像中的左心室内外膜并具有较好的鲁棒性，对于实现基于心脏MRI图像的左心室心肌区域自动快速分割和心脏功能分析与评价具有一定的应用价值。

Endocardium and epicardium segmentation of left ventricle in cardiac magnetic resonance images based on directional Snake model

Concerning that the edges of the endocardium and epicardium of the left ventricle in the cardiac Magnetic Resonance Imaging(MRI) images have different directions,a new directional active contour model in curve evolution framework was proposed for segmentation of endocardium and epicardium of the left ventricle.The curve evolution equation included a hybrid geometric flow with edge and region gray characteristics that were obtained from the image itself.The edge-based term in the geometric flow borrowed from extended Dynamic Directional Gradient Vector Flow(DDGVF) with fast marching method was utilized to guide the curve evolution towards the object boundaries with different direction.The region-based term borrowed from Chan-Vese(CV) model was utilized to prevent the curve from leakage under the influence of other edge components.The final curve evolution equation was dealt with level set method.The experimental results for gray and cardiac MRI images show that the proposed method can get better segmentation effects.It has certain application value for realizing myocardium auto-segmentation,evaluation and analysis of heart function based on cardiac MRI images.