Parallel Transmission Effect on RF-induced Local SAR of Face Mask during 3T MRI

Since face masks may help slow the spread of diseases, a patient may wear a face mask for an MRI exam during the COVID-19 pandemic. However, metal parts, like nose or face clips within the mask, may burn the patient during an MRI. In this numerical study, we investigated the two-channel RF shimming effect on the RF-induced local SAR of a face mask with a metal strip. With the parallel transmission RF field exposure to the virtual adult male model with a face mask, the RF-induced local SAR
1g
is calculated for each excitation condition. Under the exposure limit of a whole-body averaged SAR of 2 W/kg and head averaged SAR of 3.2 W/kg, the peak SAR
1g
is 178 W/kg and 62 W/kg occurs at the nose touching the metal strip. The SAR
1g
value is higher on the skin area close to the metal strip than at other locations. The metal strip within the face mask could cause a potential RF-induced heating hazard.