Electromagnetic field distribution and developed losses inside a finite cylinder and sphere under MRI conditions

The control of the thermal losses dissipated inside the human body during magnetic resonance imaging (MRI) is very important, since it is directly related to patient safety. The authors give the exact solution to the problem of the electromagnetic energy dissipation and distribution inside a conductive sphere and a finite conductive cylinder, considered as the closest models to the human anatomy. The high-frequency alternating magnetic field is produced by a current loop. Numerical results are given for alternating fields from 6 to 100 MHz and various excitation geometries. The results, which take into account the magnetic field inhomogeneities and the finite dimensions of the conductive models, apply not only to the MRI experiments but also to any similar eddy-current problem.