Beyond fetal magnetic resonance diagnosis of corpus callosum agenesis

Background Corpus callosum agenesis (CCA) is a midline congenital anomaly. Routine prenatal 2D ultrasonography (2D US) can suggest CCA. A definitive diagnosis and identification of more subtle associated neurological or non-neurological abnormalities are difficult to be detected by prenatal 2D US; therefore, a further study by fetal magnetic resonance imaging (MRI) is needed. This study highlights the role and evaluates the diagnostic value of fetal MRI in the diagnosis of CCA and identifying the associated anomalies, which is a prognostic of the postnatal developmental outcome. Results Out of 27 fetuses that were suspected to have CCA on prenatal US, fetal MRI diagnosed 25/27 fetuses (92.5%) with CCA, while the last 2/27 (7.5%) were ruled out; being false positive (FP) on prenatal US, they had normal corpus callosum (CC). Cases diagnosed as CCA were either complete 77.7% (n = 21) or partial agenesis 14.8% (n = 4). They were classified as followed: Only 5/25 (18.5%) had isolated CCA, while the majority 20/25 (74%) of CCA were complex form associated with other anomalies (most of them 14 cases (70%) associated with other neurological anomalies, while 4 cases (20%) associated with other non-neurological anomalies, and last 2 cases (10%) were having both anomalies). The diagnostic performance of fetal MRI in diagnosis of CCA was as follows: sensitivity 100%, specificity 67%, positive predictive value (PPV) 96%, negative predictive value (NPV) 100%, and accuracy 96.3%. The sensitivity of the detection of associated neurological abnormalities was 100% by fetal MRI for 75% by 2D US. Conclusion The prevalence of the complex CCA is higher than the isolated form. Fetal MRI is a valuable adjunctive complementary imaging to prenatal 2D US with high diagnostic performance in the diagnosis of fetuses with CCA. It confirms the diagnosis, assesses the extent of agenesis, and detects coexisting anomalies, which is a prognostic of the postnatal developmental outcome.