A system for determining field of ablation is disclosed. The system includes a power source configured to generate electromagnetic energy and an energy applicator coupled to the power source. The energy applicator is configured to be inserted into tissue and to provide electromagnetic energy to a target volume. The system also includes an imaging apparatus configured to generate a uniform magnetic field and at least one variable magnetic field around the tissue. The imaging apparatus obtains an image of a field of ablation within the target volume in response to a trace RF pulse supplied by the power source through the energy applicator to the target volume simultaneously with an excitation RF pulse generated by the imaging apparatus and the at least one variable magnetic field.
