Numerical analysis of time-varied radio frequency induced heating on and near an implant during magnetic resonance imaging

We numerically investigated volume loss density and temperature rise generated due to presence of a titanium rod placed in an ASTM F2182-11a high permittivity medium which was excited by radio frequency (RF) 64 MHz plane waves. 3-D electromagnetic and thermal co-simulations were performed for continuous wave and time-varied excitations. If time variable RF excitation that reaches the limit set by the short duration specific absorption rate limit and the implant thermal time constant is comparable to or less than 10s, RF induced heating on and near an implant during magnetic resonance imaging can be up to factor of 2 higher than RF induced heating caused by continuous RF excitation reaches the limit set by whole body specific absorption rate limit defined by IEC 60601-2-33. If the thermal time constant is significantly longer than 10 s, continuous wave excitation results in a reliable assessment of the maximum temperature rise.