Magnetic resonance microwave absorption imaging: initial experimental results in phantoms

We have used phase contrast magnetic resonance gradients to image small displacements induced by a pulsed 434 MHz microwave field. Thermoelastic expansions, which are related to the tissues' local microwave absorption properties and the applied microwave field distribution are encoded into the phase of MR images. The imaging principles are applicable to other irradiation sources. Initial efforts to develop the signal generation and control necessary for synchronous pulsed microwave power deposition and MR image acquisition have been successful. Preliminary results suggest that MR phase accumulation associated with microwave power deposition in a localized absorber has been observed.