RF induced temperature elevation near metallic wires in clinical magnetic resonance imaging

Heating of biological tissues along metallic wires placed in MRI scanner has become an important question with the development of interventional MRI. In order to assess thermal response to RF exposure during MR procedures, the temperature elevation was studied near metallic non-magnetic wires. All tests have been performed on a 1.5 T clinical scanner. The major issue is to insure patient safety against potential heating of tissues located in the metallic wire vicinity. Three experiments were conducted: the first investigate the wire diameter, the second the excitation angle, and the third, the temperature distribution along the wire. This study shows that the temperature decreases with the diameter wire. The temperature range increases quadratic with excitation angle. Heating has also been observed along the wire, and results indicate that heating peaks are located according to electrical length of the wire. In the close vicinity of the wire, an important heating (40 °C rise) has been observed. Electromagnetic simulations of experimental set up were made assuming a plane wave excitation with FEKO software. Correlations between measured and calculated values of electric field are presented.