Variability in antenatal prognostication of congenital diaphragmatic hernia by magnetic resonance imaging across the North American Fetal Therapy Network (NAFTNet)

Objective: To evaluate the variability in magnetic resonance imaging (MRI)-based parameters used for fetal lung volume estimation in the prediction of pulmonary hypoplasia and the degree of liver herniation in cases of antenatally diagnosed left congenital diaphragmatic hernia (CDH) across North American Fetal Therapy Network (NAFTNet) centers. Methods: In this study, 14 NAFTNet radiologists reviewed MRI exams of 15 cases of left CDH of variable severity, eight of which had liver herniation confirmed at surgery. Images were obtained at a median gestational age of 29.3 (range, 25.0-37.6) weeks, between 2020 and 2022. All participants were asked to rate image quality using a scale of 1-4 (where 1 represents excellent quality and 4 represents poor quality (unable to perform measurements)) and to determine the observed-to-expected total fetal lung volume (o/e-TFLV) using the formulae of Rypens et al. and Meyers et al., the percent predicted lung volume (PPLV), the presence or absence of liver herniation and the percentage of liver herniation (%LH). Fleiss' κ was used to assess inter-rater agreement for image-quality ratings. Concordance between participants was evaluated by determining a coefficient of variation (CV), with CV < 30 defined as acceptable. Additionally, the variation of individual participant's assessment of a case from the group average was also assessed. Data were also evaluated by center case volume, for which high volume was indicated by ≥ 15 CDH cases/year and low volume was indicated by < 15 CDH cases/year managed prenatally. Results: Overall, there was acceptable concordance for o/e-TFLV among reviewers using the formula of either Rypens et al. or Meyers et al. (median CV, 24 (interquartile range (IQR), 19-34)). Slightly lower but acceptable concordance was noted for PPLV (median CV, 26 (IQR, 18-42)). For the determination of liver herniation, most participants agreed with the final diagnosis at surgery in 14/15 cases; however, concordance was lowest among reviewers for the quantification of %LH (median CV, 46 (IQR, 44-53)). Among the three MRI exams rated as being of poor quality by the majority of participants, CV was higher for o/e-TFLV (median CV, 39) and PPLV (median CV, 43), indicating poor concordance among reviewers. No significant difference was noted in concordance among reviewers for the assessment of lung volume and liver herniation based on a center's CDH volume. Conclusion: Noticeable variability with acceptable agreement was noted for o/e-TFLV, PPLV and determination of liver herniation between NAFTNet radiologists from 14 centers in cases of left CDH. However, significant heterogeneity was noted for %LH. Concordance among reviewers was similar, irrespective of center case volume, highlighting the need for standardization of imaging protocols and CDH prognostication by MRI. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.