Research On The Method And Application Of Multi-point Time-sharing Excitation Shear Wave Ultrasonic Elastography

Ultrasound elastography plays an important role in medical detection.It can detect the elasticity of soft tissue qualitatively and quantitatively through non-invasive way.And it provides important basis for clinical diagnosis of several diseases by real-time,rapid and high-resolution imaging.The credibility and error of elastic information reflected in elastic imaging depend on the quality of shear wave push-catch,which is an important part of elastic imaging technology.In this paper,based on the principle of plane wave coherent compound,for the problem of the complex control excitation effect the quality of elastic imaging and the problem of broadening of shear wave in multi angle space compound imaging during capturing,to solve the problem,shear wave time-sharing excitation is proposed and the captured shear wave is coherently compounded.The complex excitation mode and capture mode are divided into time and the equivalent work is done at the data processing.We have done the following research:(1)The time-sharing excitation and coherent compound shear wave can achieve any angle with smaller step compared with SSI.It solved the problem of image quality caused by complex control of excitation and increase the application range of traditional shear wave.Using this method,the tail shadow problem caused by compound plane wave when catching shear wave is solved by divided each angle plane wave in slow time.At the same time for the diffusion of shear wave excited by acoustic radiation force,the direction of wave-front propagation is not agreement with the direction of the reconstruction.In this method,the wave-front is parallel to wave source moving direction and propagation agree with the reconstruction direction to avoid errors.(2)In this paper,we combine the dynamic aperture technology with the time-sharing excitation method by using fewer elements in the near field and using more elements in the far field to discuss the influence of different dynamic aperture methods on the excitation beam.The method of changing number of array elements with the focus depth and the method of changing array elements by finite F-number is compared.And it is shown that,the method of finite F-number has better excitation beam.(3)The method is combined with the deflection focusing to open up new approach.In the detection of anisotropic soft tissue elasticity characteristics,according to the mechanical rotation sound transmission path problem,in this paper,time-sharing excitation method is proposed to enhance the amplitude of steered shear waves.This method provides a technical method for using multi angle shear wave anisotropy detection.Theoretical and experimental results show that the shear wave-front synthesized by this method is clear and scanning range is large,which is good application value for improving the imaging quality and detection efficiency of shear wave elastography.