Temperature changes caused by MR imaging of the brain with a head coil.

Tissue heating caused by exposure to RF radiation is a primary safety concern in MR imaging. Therefore, to determine temperature changes caused by high field strength MR imaging of the brain with a head coil, we measured body and skin temperatures in 35 patients immediately before and after clinical MR imaging. MR imaging was performed with a 1.5 T MR system using a 28-cm, open-bore RF transmit/receive head coil specifically designed for examinations of the brain. The average body temperature was 36.6 +/- 0.2 degrees C before MR imaging and 36.6 +/- 0.2 degrees C immediately afterward (mean +/- SD, p = not significant). The average forehead skin temperature increased from 32.6 +/- 0.6 to 32.8 +/- 0.5 degrees C (p less than .01), and the average outer canthus skin temperature increased from 32.1 +/- 0.6 to 32.7 +/- 0.6 degrees C (p less than .01) after MR imaging. The highest skin temperature recorded was 34.2 degrees C, and the largest temperature change was +2.1 degrees There were no statistically significant changes in the average skin temperatures of the upper arm and hand. We conclude that patients undergoing MR imaging of the brain with a head coil at the RF radiation exposure we studied experience no significant changes in average body temperature and statistically significant increases in local (i.e., areas within the head coil) skin temperatures. The observed elevations in skin temperatures were physiologically inconsequential.