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LOCAL AND GLOBAL THERMOREGULATORY RESPONSES TO MRI ELECTROMAGNETIC FIELDS
Citation:
Gordon, C. LOCAL AND GLOBAL THERMOREGULATORY RESPONSES TO MRI ELECTROMAGNETIC FIELDS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/D-91/228 (NTIS PB91242941), 1991.
Description:
Current U.S. exposure guidelines restrict core temperature (Tc) from increasing over 1.0 degrees C and skin temperature (Tsk) from exceeding 40 degrees C during MR. mall number of studies suggest that these limits are not reached in most clinical scans. AR's of < 0.4 W/kg have little effect on thermoregulation. AR's of 0.4 to -2.0 W/kg elicit significant elevations in Tc and Tsk, but the temperature elevations are relatively safe. n SAR of 4.0 W/kg cause a 0.3 degrees C increase in Tc and 3.0 degrees C increase in 20 min of MR. ormation of "hot spots" is expected to be of little concern; however, there is little known on thermal homeostasis in the CNS of humans during MRI. tudies in anesthetized sheep suggest that significant warming of the brain occurs during a head scan. ssues remaining to be answered include potential problems of perceiving RF-induced thermal injury, role of compromised thermoregulatory function, and vulnerability of susceptible tissues and organs such as the CNS, cornea, and scrotum.