Abstract
BACKGROUND: Pulsed radiofrequency (RF) magnetic fields, required to produce magnetic resonance imaging (MRI) signals from tissue during the MRI procedure have been shown to heat tissues. OBJECTIVES: To investigate the relationship between body temperature rise and the RF power deposited during routine clinical MRI procedures, and to determine the correlation between this effect and the body's physiological response. PATIENTS AND METHODS: We investigated 69 patients from the Korean national cancer center to identify the main factors that contribute to an increase in body temperature (external factors and the body's response) during a clinical brain MRI. A routine protocol sequence of MRI scans (1.5 T and 3.0 T) was performed. The patient's tympanic temperature was recorded before and immediately after the MRI procedure and compared with changes in variables related to the body's physiological response to heat. RESULTS: Our investigation of the physiological response to RF heating indicated a link between increasing age and body temperature. A higher increase in body temperature was observed in older patients after a 3.0-T MRI (r = 0.07, P = 0.29 for 1.5-T MRI; r = 0.45, P = 0.002 for 3.0-T MRI). The relationship between age and body heat was related to the heart rate (HR) and changes in HR during the MRI procedure; a higher RF power combined with a reduction in HR resulted in an increase in body temperature. CONCLUSION: A higher magnetic field strength and a decrease in the HR resulted in an increase in body temperature during the MRI procedure.