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Project Summary

Medical imaging modalities use different physical properties of living tissues for imaging, such as X-ray attenuation coefficient (Computerized Tomography), proton density (Magnetic Resonance Imaging), and ultrasonic reflection coefficient (Ultrasound Imaging). Electrical properties of a body tissue (conductivity and permittivity) are of great importance for medical imaging, due to a number of reasons:

  1. These properties can vary greatly among tissues; the size of different tissues/organs can be observed.
  2. The impedance of a diseased tissue changes; therefore impedance change is an indication for a disease.
  3. Tissue impedance imaging provides better contrast as compared to the other imaging modalities.
  4. Impedance is a frequency dependent parameter; hence, it is possible to obtain several different images of the same object by means of the impedance imaging.

In this project, the aim is to develop a hybrid imaging system to image the electrical impedance of tissues. To obtain impedance images, several methodologies have been proposed:

  1. Current injection via the electrodes placed on the surface of the body.
  2. Current induction via alternating magnetic field.
  3. Current induction via acoustic waves inside the static magnetic field.

The third method is based on the Lorentz fields, which is created by acoustic vibrations generated by ultrasonic transducers placed on the surface of the tissues placed in static magnetic fields. The source of electric fields propagate in the conductive body with the ultrasonic propagation velocity. In this project, the third method will be investigated using a new measurement technique. The electrodes attached on the tissues can sense the velocity-current density. In this project, we propose to use magnetic field measurements using the coils encircling the body.