Research On Low Intensity Focused Ultrasound-Based Electrical-Elastic Dual-Mode Measurement Method

Electrical and mechanical properties of biological tissues are important functional indicators closely related to pathological conditions,which are of great value for the early diagnosis of diseases.A low intensity focused ultrasound-based electrical-elastic dual-mode measurement method is proposed.The acoustic radiation force pulse(ARFI)imaging method and the acousto-electric tomography(AET)method are optimized.Using the same low-intensity focused ultrasound excitation,these two imaging methods are combined to detect the functional indicators of biological tissues.The main research of this paper is as follows.(1)Optimization of ARFI imaging method.The relationship between mechanical properties of the medium and the displacement response at the lateral position of the focal depth is constructed.An ARFI imaging method using the maximum displacement at the lateral position is proposed to reconstruct the elastic property distribution of the medium.The simulation and experimental results show that this method can increase the range of ARFI under a single ultrasound excitation,and reduce the impact of the ultrasonic heating effect induced by focused ultrasound on the tissue.(2)Proposal and optimization of non-invasive AET method.The electrical response of biological tissues caused by acousto-electric effects and the resulting acousto-electric signals are analyzed.A non-invasive AET method is preliminarily studied and designed.Aiming at reducing artifacts in imaging results caused by the distribution characteristics of electric field in the measurement field,a sensitivity matrix compensation method based on Geselowitz’s theory is established to solve the problem that the acousto-electric signal generated near the electrodes is too large and then optimize the imaging quality.(3)An electrical-elastic dual-mode measurement method is proposed.Through the mechanical responses and acousto-electric effects generated by the same low-intensity focused ultrasound excitation,the displacement and electrical characteristic changes are induced in the measured biological tissue,and the elastic as well as electrical parameters at the same position of the biological tissue are obtained simultaneously.The dual-mode imaging result is calculated by the weighted average fusion algorithm.Compared with the single-mode imaging results,the imaging results of the electrical-elastic dual-mode imaging method can obtain the distribution of the measured tissue more comprehensively.