Research And Implementation Of Ultrasonic Elastography

Elastic imaging technology is important in the diagnosis and detection of diseases by providing the data of tissue elastic modulus.Prior to the application of this technology in clinical practice,doctors generally use palpation method to detect the changes of tissue hardness,which has the disadvantages of subjective,poor repeatability,shallow diagnosis and so on,which is not conducive to the diagnosis and treatment of some diseases.Elastography to compensate for the lack of traditional imaging techniques,combined with ultrasound imaging can provide morphological information and flexible information organization,which provides a new method for disease examination and diagnosis.At present,ultrasound elastography becomes hotspot of medical imaging.The main research object of this paper is the static or quasi-static ultrasound elastography.The first part is the one-dimensional displacement and strain estimation.Displacement estimation can be divided into displacement estimation based on time domain and frequency domain,its core is calculating displacement of before and after the corresponding RF signal window.Before computing,RF signal has to be preprocessed by time domain extension and the amplitude frequency characteristic to improve signal window correlation.Finally,after displacement estimation Caiman filtering,the strain estimation is obtained by using convolution operator.On the basis of optical flow method,this paper proposes an estimation method based on two-dimensional strain vector field estimation.It uses the fingerprint information of envelope peak as feature point optical flow tracking,to reduce the error and realize two-dimensional displacement estimation.The corresponding strain estimation results are obtained by designing a specific convolution operator to realize the fast difference calculation of two-dimensional displacement field.The third part is the design and analysis of experiments,described how to generate simulated ultrasound RF signals by finite element analysis software COMSOL and field simulation software FIELD ?.Then validate the algorithm with four different models.Compared with the one-dimensional displacement estimation,pretreatment before two-dimensional correlation calculation of displacement can effectively improve the calculation speed and accuracy.