Temperature Changes in the Brain due to External Heat Sources: an MR Thermometry Study

Motivation: RF-induced temperature rise is considered a safety risk for MRI. Goal(s): To study temperature changes in the brain due to (generally considered safe) heat or cool pads placed on a subject's forehead for comparison to RF-induced temperature elevations. Approach: Using the Projection onto Dipole Fields method, susceptibility and drift induced field changes are separated from temperature effects to enable assessment of temperature rise in the brain. Results: Up to 2.5 °C temperature rise was measured at the brain edge in 2 volunteers. Similarly, a 2.0 °C decrease was observed at the brain edge when a coolpad was placed on the forehead. Impact: RF-induced temperature changes in the brain can be considered modest compared to temperatures induced by (generally considered safe) external heating/cooling sources. The temperature increase due to a heatpad on the forehead is much larger than previously measured RF-induced temperature increases.