Role of prenatal magnetic resonance imaging in fetuses with isolated anomalies of the corpus callosum: a multinational study.

OBJECTIVES To assess the role of fetal magnetic resonance imaging (MRI) in detecting associated anomalies in fetuses presenting with isolated corpus callosum (CC) anomalies at multiplanar ultrasound (US) evaluation of fetal brain (neurosonography). METHODS Multicentre, retrospective, cohort study involving 14 fetal medicine centres in Italy, United Kingdom, Portugal, Canada, Austria and Spain. Inclusion criteria were fetuses with an apparently isolated CC anomaly, defined as an anomaly of the CC with normal karyotype and no other additional central nervous system (CNS) or extra-CNS abnormalities detected at expert US including multiplanar neurosonography. The primary outcome was to report the rate of additional CNS abnormalities detected exclusively at fetal magnetic resonance imaging (MRI) within two weeks from neurosonography; the secondary aims were to estimate the rate of additional abnormalities according to type of CC abnormalities [complete, (cACC) or partial (pACC) agenesis of the corpus callosum], and the rate of additional anomalies detected only at post-natal imaging or at post-mortem examination. RESULTS Two-hundred and sixty-nine fetuses with a sonographic prenatal diagnosis of apparently isolated CC anomalies (207 with cACC and 62 with pACC), were included in the analysis. Additional structural anomalies of the CNS were detected exclusively at prenatal MRI in 11.2% (30/269) of cases, with malformations of cortical development representing the most common type of anomaly. When stratifying the analysis according to the type of anomaly, the rate of associated anomalies detected exclusively at MRI was 11.6% (24/207) in cACC and 9.7% (6/62) in pACC. At multivariate logistic regression analysis, only maternal BMI (OR: 1.07, 95% CI 1.0-1.1, p= 0.03) was independently associated with the likelihood of detecting associated anomalies at MRI. Finally, associated anomalies were detected exclusively at birth and missed at both types of prenatal imaging in 3.9% (8/205) of fetuses with isolated anomalies of the CC at prenatal imaging (both ultrasound and MRI). CONCLUSIONS In fetuses with isolated anomalies of the CC diagnosed at antenatal neurosonography, MRI can identify a small proportion of additional anomalies, mainly malformations of cortical development, not detected at ultrasound. This article is protected by copyright. All rights reserved.