Myocardial motion tracking method integrating local-to-global deformation for echocardiography

Abstract

Automated tracking of left ventricle (VL) border is required for the quantitative analysis of echocardiography. Commonly, after an initial contour of LV border is traced at one or two frame from the entire cardiac cycle, LV contour tracking is performed over the remaining frames. Among a variety of tracking techniques, optical flow method is the most widely used for motion estimation of moving objects. However, it is often difficulty for the optical flow method to automatically track the motion of LV border in sequential echocardiography data due to some reasons such as ultrasound artifacts, dropout or shadowing phenomena of cardiac walls. The tracking errors caused by those image limitations bring the tracking point out of the endocardial border, result in distorted LV contours and provide incorrect LV assessments. The proposed method is designed to deal with this shape distortion problem by integrating local optical flow motion and global deformation into a variational framework. The proposed descent method controls the individual tracking points to flow the local motions of a specific speckle pattern, while their overall motions are confined to the global motion constraint being approximately an affine transform of the initial tracking points. Preliminary results show that the proposed method achieves better overall performance than conventional methods.