Evaluation of twin fetal exposure to radiofrequency field during magnetic resonance imaging.

This article focuses on assessing radiofrequency (RF) exposure during magnetic resonance imaging (MRI) in twin pregnancies by developing two whole-body pregnant models at 31 and 32 gestational weeks (GWs) using MRI data and a hybrid modeling technique. Simulations of RF exposure at 1.5 and 3.0 Tesla (T) MRI showed that fetal peak local specific absorption rate averaged over 10 g tissue (pSAR10g) can vary by about 35% due to differences in fetal position and weight, with larger fetuses and certain positions leading to higher exposure. Although twin fetuses were not significantly more exposed than singletons overall, some cases (e.g., 31 GW fetuses at 1.5 T) exceeded recommended exposure limits, highlighting the need for individualized assessment of MRI sequences in twin pregnancies. The study also noted that maternal whole-body SAR was higher than fetal SAR and emphasized the importance of further research using anatomically accurate twin-fetal models across various gestational stages.