Objective: To evaluate MR contribution to prenatal diagnosis and prognosis of corpus callosum agenesis suspected by ultrasound and to ascertain how and when this examination should be included part in prenatal management of such malformation.
Patients and methods: During a six-year period from January 1st 1994 and December 31st 2000, fifteen patients (and fifteen fetuses) were referred to our fetal medicine unit with suspicion of corpus callosum agenesis on prenatal ultrasound. Cerebral MRI was performed in all cases to confirm prenatal diagnosis. In our study, prenatal MRI examinations were retrospectively studied and compared with neuropathological examinations (n=8) or postnatal imaging (n=6).
Results: Corpus callosum agenesis were either complete (n=13) or partial (n=1). All were visible on prenatal MRI but only six on prenatal ultrasound. In one case, ultrasound suspicion of corpus callosum agenesis was ruled-out (false positive on prenatal ultrasound) by fetal cerebral MRI. In five cases corpus callosum agenesis was an isolated finding whereas in 12 cases associated malformations were encountered (cerebral n=7 or extra-cerebral n=5). MR depicted 7 of the 12 associated neurologic abnormalities.
Conclusion: Prenatal MRI is a valuable complementary technique for either diagnosis of corpus callosum agenesis and depiction of associated neurologic abnormalities. Superiority of MR on prenatal sonography and its help in post-mortem examination of the brain (help in the choice of the pathologic technique and localisation of the samples) makes it essential even when pregnancy termination is considered.