title: Periventricular nodular heterotopia on prenatal ultrasound and magnetic resonance imaging.
abstract: OBJECTIVE
  To describe the prenatal ultrasound and magnetic resonance imaging (MRI) findings suggestive of periventricular nodular heterotopia (PNH).
  
  
  METHODS
  This retrospective case series included fetuses referred to our institution for brain MRI between 2007 and 2012, which were diagnosed with PNH and confirmed by postnatal MRI or autopsy. The type of PNH, associated ventriculomegaly and associated malformations are reported.
  
  
  RESULTS
  We included 11 fetuses (nine female, two male) with a mean gestational age at diagnosis of 31 (range, 23-34) weeks. PNH lesions were small and diffuse (n = 7), large and multiple (n = 1) or single (n = 3). A targeted ultrasound examination performed before fetal MRI missed the diagnosis in four cases (one diffuse and three single); a further ultrasound examination performed after MRI diagnosed PNH in two of these four cases. Ventriculomegaly was present in six cases (four unilateral and two bilateral). PNH appeared in all cases as nodules of intermediate echogenicity protruding into the ventricular lumen. In all cases of diffuse PNH, the frontal horns and bodies of the lateral ventricles appeared square in shape on coronal view, with irregular borders on axial view. Associated cerebral malformations were observed in seven cases and included corpus callosal agenesis (n = 4, with additional malformations in two) and retrocerebellar cyst (n = 3). Extracerebral malformations were also present in two cases. Maternal MRI was performed in five of the six cases of isolated small and diffuse PNH in female fetuses, and demonstrated PNH in two of these.
  
  
  CONCLUSIONS
  PNH is underdiagnosed at prenatal ultrasound, even on targeted scans. Irregular ventricular borders on axial view and irregular square-shaped lateral ventricles on coronal view are suggestive of PNH at prenatal ultrasound.
authors.affiliation: Service de Radiologie, Hôpital Trousseau, Hôpitaux Universitaires de l'Est Parisien (APHP), Université Pierre et Marie Curie, Paris VI, France. eleonore.blondiaux@trs.aphp.fr
authors.forename: E
authors.initials: E
authors.lastname: Blondiaux
authors.forename: C
authors.initials: C
authors.lastname: Sileo
authors.forename: C
authors.initials: C
authors.lastname: Nahama-Allouche
authors.forename: M L
authors.initials: ML
authors.lastname: Moutard
authors.forename: A
authors.initials: A
authors.lastname: Gelot
authors.forename: J M
authors.initials: JM
authors.lastname: Jouannic
authors.forename: H
authors.initials: H
authors.lastname: Ducou le Pointe
authors.forename: C
authors.initials: C
authors.lastname: Garel
mesh_terms: D001344:Autopsy; D002552:Cerebral Ventricles / Q000002:abnormalities; D057210:Delayed Diagnosis; D005260:Female; D064448:Filamins / Q000235:genetics; D005865:Gestational Age; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009154:Mutation / Q000235:genetics; D054091:Periventricular Nodular Heterotopia / Q000175:diagnosis* / Q000235:genetics; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods
chemical_list: C578663:FLNA protein, human; D064448:Filamins