The Research On Magneto-Acousto-Electrical Tomography(MAET) Based On Linearly Frequency-Modulated(LFM) Excitation

The physiological and pathological changes of human tissues can lead to the change of electrical properties of tissues.Therefore,developing functional imaging methods that measure electrical properties,which provides information for early diagnosis of diseases,has important clinical significance.This thesis researches on the method of Magneto-Acousto-Electrical Tomography(MAET).MAET is a multi-modal and functional imaging method,has the advantages of ultrasonic excitation and electromagnetic detection imaging mode,can obtain the conductivity information of the tissue,so it has good clinical application prospects.This thesis studies the MAET from three aspects:the theoretical and methodology research,the experimental platform construction and experimental studies on phantoms.In the theoretical and method research part,this thesis studies the imaging method based on Linearly Frequency-Modulated(LFM)excitation.In order to reduce the influence of focusing position on the imaging effect in the ultrasonic excitation process,this thesis proposes a multi-focus excitation imaging method,which theoretically improves the existing methods.In the construction of experimental platform part,this thesis constructs the imaging experiment platform based on Verasonics open platform as the core of the ultrasonic.Verasonics can collect,process and display the MAET signal,which has full flexibility and extensibility.In the experimental research part,this thesis verifies the principle of imaging and the feasibility of the experimental platform through copper experiments.Then some experimental research on different shapes and conductivity of phantom,which detects conductivity.This thesis also experiments on multi focus imaging method of excitation,and studies this imaging method to improve of imaging effect.In this thesis,the position information of the conductivity changing interface and the image of the conductivity can be obtained by using the MAET based on LFM excitation.The use of multi focus method to excite the phantom,effectively solves the influence of the focus location on the conductivity boundary signal-to-noise ratio,and obtains the high signal-to-noise ratio of the MAET signal and higher resolution conductivity image.In the last part of this thesis,an analysis on the application prospects of the MAET based on LFM excitation and a summary of all the work related to this thesis are provided.Some research for the future work are discussed.