High-Precision Temperature Measurement System for Magnetic Resonance Imaging

To determine the compliance of an implantable medical device with the safety requirements in magnetic resonance imaging, an experimental assessment of the heating of this device during a study is necessary. The use of traditional methods, such as thermocouple measurements or radiation thermometry, is difficult in the conditions of a magnetic resonance imaging room. A spectrometric system for measuring temperature in conditions of a magnetic resonance imaging room is proposed. The developed system has a sensitivity of 0.01°C and an error of 0.1% in the range of 10–50°C. The temperature sensors used in the system are Fabry–Perot interferometers. The design of the sensors and the method of calibration are described. The system was tested in determining the heating of two passive implants during the study in a magnetic resonance imager with a magnetic field induction of 1.5 T. The compliance of the developed system with the recommendations adopted in magnetic resonance imaging for evaluating the heating of implantable medical devices is demonstrated. The temperature value obtained is comparable with the value found during testing of this implant according to ASTM F 2182. The presented measuring system can be used to assess the magnetic resonance compatibility of implantable medical devices, to develop scanning protocols for patients with metal structures, as well as to confirm or refi ne mathematical models of heat transfer.