Measurement of left ventricular global longitudinal strain using optical flow in 3-D echocardiography

Abstract

Quantitative analysis of cardiac functions using 3-D echocardiography is the most widely used technique to diagnose the dilated cardiomyopathy (DCMP). In particular, the left ventricular global longitudinal strain (GLS) is considered as a superior parameter to the traditional ejection fraction. To track the inner left ventricle (LV) wall accurately even in the case of large displacement, we adopt an improved optical flow method. In Horn and Schunck's model, optical flow can be obtained under the grey value constancy assumption with smoothness constraints. In our model, the ability to find large displacements is improved by the coarse-to-fine strategy with forward-backward consistency test. Finally, the inner LV wall is tracked along the flow accurately with reinitialization technique and the GLS is calculated with this node point displacements. In this thesis, we implement the improved Horn and Schunck's algorithm with the coarse-to-fine strategy and the GLS calculation algorithm with the reinitialization technique based on the level set method. We also verify the results for four human heart ultrasound images to diagnose DCMP.