Evaluation of MRI RF probes utilizing infrared sensors

The magnetic resonance imaging (MRI) coil's radio frequency (RF) field distribution has a strong effect on image quality as well as specific absorption rate. In this paper, a method of probing a coil's RF field distribution over any unoccupied region of the coil is presented. This technique is based on the use of infrared sensing. The proposed method was implemented and tested on a high field RF volume coil operating at 340 MHz. Very good agreement was achieved between the infrared measurements and numerical data obtained utilizing an in-house three-dimensional finite-difference time-domain package. The results demonstrate that the proposed technique is practical, robust, and efficient in making accurate measurements of the electric field distributions in loaded and unloaded MRI coils.