Theoretical and experimental investigation of the relationship among SAR, tissues and radio frequencies in MRI

The specific absorption rates (SAR) of three tissues (muscle, brain, bone) are investigated both theoretically and experimentally for MRI at the first time. Finite difference time domain (FDTD) analysis is used to simulate the average SAR of three tissues at three magnetic field strengths (0.5 T, 1.5 T, 3T). Simulations show that the SAR of muscle, brain and bone increase 7.49 folds, 10.87 folds and 12.92 folds respectively when the magnetic field strength increases from 0.5 T to 3 T. Experiments are carried out to measure SRAS of different phantoms which simulate the three human tissues at 1.5T and 3T. The experiment results agree with the simulation data very well and within only 11% difference.