Brain magnetic resonance imaging increases core body temperature in sedated children.

An increasing number of children now undergo magnetic resonance imaging (MRI) under sedation. MRI requires a cool environment. Because children have a larger surface area to body weight ratio than adults and because active warming devices are not MRI compatible, hypothermia as a result of passive heat loss is a risk. Absorption of radiofrequency radiation generated by the scanning process, however, may partially offset this heat loss. To determine the effect of absorbed radiofrequency radiation on body temperature during MRI, we measured pre-MRI and post-MRI tympanic temperatures in 30 children who underwent brain MRI while sedated with chloral hydrate and covered with a hospital gown and blanket. The mean (+/- sd) age was 14.9 +/- 8.6 mo, and weight was 9.8 +/- 2.8 kg. During an average scan duration of 42 +/- 13 min, mean tympanic temperatures increased 0.5 degrees C from 36.9 degrees C +/- 0.4 degrees C to 37.4 degrees C +/- 0.3 degrees C; (95% CI difference, 0.3 degrees C to 0.7 degrees C; P < 0.001). Our findings suggest that children sedated with chloral hydrate for brain MRI did not become hypothermic but rather had increased body temperature despite minimal barriers to heat loss and no active warming. These results imply that aggressive measures to prevent passive heat loss during MRI studies may not be needed in all patients.