Evaluation of specific absorption rate and heating in children exposed to a 7T MRI head coil

This is the authors' abstract. We don't add key points for this paper.

PURPOSE: To evaluate specific absorption rate (SAR) and temperature distributions resulting from pediatric exposure to a 7T head coil. METHODS: Exposure from a 297-MHz birdcage head transmit coil (CP mode single-channel transmission) was simulated in several child models (ages 3-14, mass 13.9-50.4 kg) and one adult, using time-domain electromagnetic and thermal solvers. Position variability, age-related changes in dielectric properties, and differences in thermoregulation were also considered. RESULTS: was greater, but in most cases hdSAR remained the limiting quantity. For thermal simulations, if blood temperature is fixed (i.e., asserting good thermoregulation), maximum temperatures are compliant with International Electrotechnical Commission limits during 60-min exposure at the SAR limit. Introducing variable blood temperature leads to core temperature changes proportional to whole-body averaged SAR, exceeding guideline limits for all child models. CONCLUSIONS: Children experienced higher SAR than adults for the 297-MHz head transmit coil examined in this work. Thermal simulations suggest that core temperature changes could occur in smaller subjects, although experimental data are needed for validation.