SAR and temperature changes in the leg due to an RF decoupling coil at frequencies between 64 and 213 MHz.
Specific absorption rate (SAR) due to a butterfly surface coil in a realistic model of the leg was calculated for frequencies 64 < or = v < or = 213 MHz. The resulting temperature distribution and temperature changes (deltaT) were found using the bioheat transfer equation. To compare results at different frequencies, the minimum B-field within the coil's footprint in the plane parallel to the coil but displaced 50 mm from it was kept constant. To achieve the same minimum B-field as that associated with operation at 64 MHz that was compliant with safety guidelines (peak SAR in 1 cm3 of tissue of 2.3 W/kg), it was predicted that SAR would exceed recommended levels when v > or = 149 MHz. The corresponding maximum deltaT at 64, 128, and 213 MHz were 0.3, 1.3, and 5.0 degrees C, respectively.
Hand
J W
JW
Department of Imaging, Imperial College School of Medicine, Hammersmith Hospital, London, United Kingdom. j.hand@ic.ac.uk
Lagendijk
J J
JJ
Hajnal
J V
JV
Lau
R W
RW
Young
I R
IR
D000042:Absorption; D001833:Body Temperature Regulation / Q000502:physiology*; D004574:Electromagnetic Fields; D006358:Hot Temperature; D006801:Humans; D007866:Leg / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000098:blood supply; D019047:Phantoms, Imaging; D000078702:Radiofrequency Therapy; D012680:Sensitivity and Specificity; D013817:Thermography