Prenatal MRI of neck masses with special focus on the evaluation of foetal airway

Background: Prenatal magnetic resonance imaging is the best tool to visualize foetal airway. Objective: To evaluate the performance of MRI in the assessment of foetal airway status in the presence of a neck mass. Materials and methods: Two paediatric radiologists with 12- and 2-year experience in foetal imaging retrospectively analysed 23 foetal MRI examinations, performed between 2001 and 2016, after a second-level ultrasound suspicious for presence of a neck mass. Postnatal imaging, postoperative report, histology, autopsy, and clinical outcomes were the reference standard to calculate sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of prenatal MRI in detecting airway patency. We used the Cohen к statistics to estimate the interobserver agreement. We also assessed MRI performance in the diagnosis of the mass nature. Results: We obtained data about postnatal airway status in 19 of 23 patients; prenatal MRI demonstrated a sensitivity of 9/9 [100%, 95% confidence interval (CI) 66–100%], specificity 8/10 (80%, 44–98%), accuracy 17/19 (89%, 67–99%), PPV 9/11 (82%, 48–98%), and NPV 8/8 (100%, 63–100%); the interobserver agreement was perfect. Prenatal MRI correctly identified 21 of 23 masses (к = 0.858); the interobserver agreement was almost perfect (к = 0.851). Conclusion: Prenatal MRI demonstrated high accuracy in assessing foetal airway status and diagnosing mass nature, allowing proper delivery planning.