ABSTRACT
Objective To research the influence of the thermoacoustic effect for the frequency of the magnetoacoustic signals in the magnetoacoustic tomography (MAT).Methods Some experiments were designed,and the magnetoacoustic signals and the thermoacoustic signals of several materials with different conductivities were analyzed and compared in the time domain and the frequency domain respectively,of which,copper and graphite were high-conductivity materials,and agar and pork were used as low-conductivity biological or similar tissue.Results The characteristics of the magnetoacoustic signals and the thermoacoustic signals of different materials were acquired.The results illustrated that there was a little drop in frequencies of acoustic signals of the materials with high conductivities while a big drop in frequencies of signals of the tissue-like materials comparing with the stimulant pulse.Furthermore,the main frequencies of acoustic signals were not accordant but much lower than the stimulant ones. Conclusion It is found that the thermoacoustic effect is related to the frequency of the acoustic signals. The drop in the center frequencies of the acoustic signals could be explained by the thermoacoustic effect of materials.The acoustic signals with lower main frequencies have the higher proportion of thermoacoustic signals.The studies could contributing to optimizing MAT method and improving MAT imaging quality.
ABSTRACT
Objective To explore the effect of the transcranial ultrasound stimulation(TUS)on transcranial magneto-acoustic stimulation(TMAS).Methods The healthy mice and Parkinson's disease(PD)mice were contrastively stimulated by TMAS and TUS.A TMAS group,a TUS group and a control group were established,and then the behavior and the electrophysiology results were analyzed and compared in the three groups. Results Both the chronic TMAS treatment and TUS treatment improved the motor ability and learning ability of the healthy mice and the PD mice. In addition, the TMAS-group mice showed better performances than the TUS-group mice and the ones in the control group.Conclusion TMAS has its effects promoted by TUS and mechanism explained in detail,which is actually a combined stimulation of coupling electric field and ultrasonic field.[Chinese Medical Equipment Journal,2018,39(5):17-21,49]