What Not to Miss in Fetal Head and Neck MRI: A Pictorial Essay.

Fetal magnetic resonance imaging (MRI) is a safe method of in-utero evaluation of fetal anomalies and a valuable adjunct to prenatal ultrasound. The utilization of rapid sequences reduces the impact of fetal motion and allows for high contrast resolution of fetal structures. A thorough understanding of fetal anatomy and a systematic approach to MRI interpretation are essential for accurate diagnosis of fetal head and neck anomalies. A stepwise structural analysis of fetal head and neck structures includes the evaluation of the facial profile, including maxilla, mandible, nasal bones, and integrity of lip and palate, scalp integrity, skull morphology and proportions, and anatomy of the orbits, nasal passages, choanae, ears and neck (including visualization of the thyroid gland and airway). This approach allows for accurate and effective screening of fetal head and neck anomalies including cleft lip and palate, nasal bone abnormalities, micrognathia, craniosynostosis, skull defects, orbital anomalies, choanal atresia, ear abnormalities, goiter and head and neck masses. MRI assessment further optimizes perinatal management in cases of airway compromise by providing superior visualization of the airway column and its relationship with adjacent structures. This information helps predict a difficult airway and is essential for planning perinatal management and the delivery method, which may include EXIT (Ex-Utero-Intrapartum Treatment) procedure. Early diagnosis remains essential for parental shared decision-making, guiding counseling, and preparing families for the possible perinatal loss, limited life expectancy, or the need for supportive medical care.