Evaluation of an optical electric field sensor for measurement of specific absorption rate (SAR) during magnetic resonance imaging

This paper examines the measurement of the specific absorption rate (SAR) of radio frequency energy during magnetic resonance imaging using an optical electric field sensor (OEFS). The sensor was used to measure SAR in a simple phantom during a 3-Tesla MRI scan and the results compared to computer simulations and also those obtained through temperature measurements. Good agreement is demonstrated. The optical electric field sensor has much higher sensitivity for SAR measurement than thermometers and the measurements are much quicker. The application of this technology allows the spatial distributions of SAR within phantoms during MRI to be measured.