The local power deposited in a tissue is proportional to the tissue conductivity and the
square of the local electric field produced by the radiofrequency transmission system. The electric fields increase approximately linearly with the main magnetic field strength. Therefore, if the magnetic field strength is doubled—for example, from 1.5 T to 3.0 T—the SAR will increase by a factor of approximately four if other parameters are kept equal. As field strengths increase, techniques for estimating and managing the SAR will become more critical for patient safety.