Effect of brain magnetic resonance imaging on body core temperature in sedated infants and children

Children undergoing magnetic resonance imaging (MRI) under sedation are at risk of hypo- or hyperthermia. The effect of brain MRI at differing magnetic field strengths on body core temperature in sedated infants and young children has not been reported previously. Two groups of 38 infants and children (aged 1 month to 6 yr 5 months) underwent brain MRI for different indications related to cerebral diseases, at 1.5 Tesla (T) and 3 T MRI units, respectively. All patients received deep sedation comprising midazolam, nalbuphine, and propofol. Pre-scan and post-scan temperatures were measured at the right tympanic and at rectal sites. No active warming devices were used during the procedures. Body core temperature measurements were similar between right tympanic and rectal site before and after the scans. After 1.5 T scans, the median (IQR) increase from pre-scan to post-scan tympanic temperature was 0.2 degrees C (0.1-0.3), and the median (IQR) rectal temperature increase was 0.2 degrees C (0-0.3) (P < 0.001). After 3 T scans, the median (IQR) tympanic temperature increase was 0.5 degrees C (0.4-0.7), and the median (IQR) rectal temperature increase was 0.5 degrees C (0.3-0.6) (P < 0.001). Body core temperature increased significantly during 1.5 and 3 T examinations; this increase was more profound during 3 T MRI. Patient heating occurred despite minimal efforts to reduce passive heat loss under sedation and without the use of warming devices.