Magnetically mediated thermoacoustic imaging（MMTAI） is a novel electrical impedance tomography for early detection of human diseases

which combines the advantages of high contrast of the classic electrical impedance tomography with the high spatial resolution of sonography. In order to verify the feasibility of magnetically mediated thermoacoustic imaging for biological tissues

the principle of magnetically mediated thermoacoustic imaging was studied and the experimental system was established. The study results demonstrate that when a microsecond width pulse magnetic field is applied to an object

the object absorbs Joule heating and causes heat expansion due to the effect of induced eddy current in the object. The ultrasonic signals are sent out

which involves the conductivity information of the object. Based on the theories of electromagnetic field and acoustic field

the calculation formula of acoustic source was deduced

which revealed the relationship between acoustic source and conductivity of the object. Thermoacoustic signals produced under the action of the magneto-thermos-acoustic multi fields were detected and analyzed to reconstruct the acoustic source distribution by time reversal algorithm. The gel phantom model with the mass fraction of 10% sodium chloride was placed in the microsecond width pulse magnetic field

which caused thermoacoustic signals. After the signals were detected by ultrasonic transducer with the center frequency of 1 MHz and amplified by 60 d B

the peak value of the signals was about 4 m V. The reconstructed thermoacoustic image using 100 sets of data

which were acquired by rotating the gel phantom

could reflect the conductivity distribution of the low conductivity gel phantom. The experiments verifiy that the method for low conductivity medium imaging possesses the feasibility

and provides a basis for its potential applications to imaging in biological tissues.