Temperature stress for patients during routine magnetic resonance imaging.

Purpose: To determine energy exposure and temperature changes in routine ma gnetic resonance imaging practice. Materials and Methods: Body core and ski n temperatures were compared in 155 persons (143 patients, 12 volunteers) u ndergoing routine magnetic resonance examinations with a 1.5T field-strengt h magnetic resonance tomography unit using a fluoroptic temperature measure ment system. Results: Average applied energy was 0.3 W/kg for whole body an d 1.92 W/kg for spatially localized SAR. The maximum whole-body SAR was 1.4 3 W/kg spatially localized. Body core temperatures differed from those of t he control group by a median 0.1 degrees C and only a few patients (16.8%) exceeded the limit (+/- 0.5 %) at which regulatory mechanisms set in. All p atients remained within the normal physiological circadian temperature rang e (+/- 1 degrees C). Skin temperature rose a median 0.49 degrees C, with a maximal increase of 5.31 degrees C, which may be considered to be within th e limits of physiological temperature change. Conclusions: Clinically relev ant warming of the body is unlikely in routine magnetic resonance imaging p ractice.