Prenatal MR Findings of the Middle Interhemispheric Variant of Holoprosencephaly
Steven B. Pulitzerd,
Erin M. Simona,
Timothy M. Crombleholmeb and
Jeffrey A. Goldenc
a Department of Radiology, Childrens Hospital of Philadelphia, Philadelphia, PA
b Department of Pediatric General and Thoracic Surgery and Center for Fetal Diagnosis and Treatment, Childrens Hospital of Philadelphia, Philadelphia, PA
c Department of Pathology, Childrens Hospital of Philadelphia, Philadelphia, PA
d Department of Radiology, Mount Sinai School of Medicine, New York, NY

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FIG 1. Fetal MR images obtained at 22 weeks gestation.
A, Sagittal half-Fourier single-shot turbo spin-echo (HASTE) (TR/TE/NA, 1000/95/1) image obtained through the midline reveals the dorsal cyst and cleft formed by communication of the sylvian fissures over the vertex. Herniation of the stomach into the chest is also apparent.
B, Coronal HASTE image obtained through the midportion of the brain depicts the lack of separation of the hemispheres and absent interhemispheric fissure more dorsally.
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FIG 2. Gross specimens obtained from the stillborn female neonate.
A, Frontal view of the brain shows a clear interhemispheric fissure extending to the rostral aspect of the frontal lobes. An abnormal transverse fissure can be seen extending into the dorsal midline of both hemispheres (arrowheads).
B, Coronal section at the level of the third ventricle demonstrates bilaterally symmetric, separated basal forebrain structures (hypothalamus, basal ganglia, and anterior thalamus). In contrast, the cerebral hemispheres are continuous across the dorsal midline with a mass of white matter and cerebral cortex crossing the dorsal midline with no clear corpus callosum.
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