Application Research On 2D Speckle Tracking Echocardiography Imaging Technologies

2D Speckle Tracking Echocardiogram (2D STE) is a new technique for quantitative evaluation of cardiac function. It can obtain the movement characteristics of myocardium within a cardiac cycle by tracking and analysising speckles, which are the intrinsic properties of ultrasound images. It can achieve strain and strain rate imaging accurately, and be significant for quantitative analysis of the left ventricular (LV) twist. Speckle can be used as a marker for tracking myocardial movement due to its stability and uniqueness. Two key items of this technology are accurate speckle tracking and calculation method of strain, strain rate, LV twist and other parameters.Considering the two technical links mentioned above, this thesis focuses on the following two parts:firstly, we introduce the basic principle of 2D STE, mainly including the cause of speckles, speckle tracking feasibility and application, speckle tracking method, etc. Then we present methods of quantitative analysis of strain and strain rate imaging and LV twist. And verify the validity of the methods by simulation experiment and preliminary clinical application.Ultrasound can form stable and unique speckle patterns when acrossing the random distribution of scattered particles in the cardiac tissue. The tracking of speckles can obtain the characteristic and parameters of the motion region of myocardial, so as to provide help for further quantitative analysis for myocardial motion. This thesis uses the RATracking method which is proposed by our laboratory to track speckles. In this method, we use block matching algorithm, which includes diamond-search method and sum-of-absolute-differences method, etc. The stability and reliability of this method can meet the needs of clinical application. And lay the foundation for the second part of this thesis.2D STE strain and strain rate imaging can quantitatively evaluate myocardial function. The strain of myocardial includes longitudinal strain, radial strain and circumferential strain. The thesis independently achieves the calculation of longitudinal and circumferential strain and improves the calculation method of radial strain, combines with the latest initial document of technology standards of 2D STE and verifies the validity of the methods by simulation experiment and preliminary clinical application.The ability of relaxing and contracting of myocardial fibers can be demonstrated through the LV twist. This thesis presents a new method for quantitatively analysising LV twist, based on the preliminary work of the laboratory, and verifies the validity of the methods by simulation experiment and preliminary clinical application.