Measuring AC magnetic field distribution using MRI

Electric currents are applied to body in numerous applications in medicine, such as electrical impedance tomography, cardiac defibrillators, electrocautery and some treatment methods in physiotherapy. If the magnetic field within a region is measured, the currents generating these fields can be calculated using the curl operator. In this study, magnetic fields generated by AC currents injected into a phantom are measured using MRI. A pulse sequence that is originally designed for mapping static magnetic field is used. AC currents in the form of burst sine waves are applied synchronously with the pulse sequence. Results show that this method can be used in applications where the frequency of the currents is in the audio range and the amplitude is a few milliamperes or larger depending on SNR