Female, 17 years old, 31 weeks gestational age with IUGR and suspicion for absence of the septum pellucidum on US. The cavum septum pellucidum is present, as is the corpus callosum.Cavitation with mild ex vacuo expansion of the left lateral ventricular atrium is seen. In addition, the margins of the left atrium are rimmed with a band of abnormal signal which is T1 hyperintense, T2/gradient-echo hypointense, and hyperintense on DWI. Similar periventricular signal abnormality is also seen but to a lesser degree elsewhere around the lateral ventricles, particularly along the right occipital and temporal horns. In addition, the right anterior temporal horn is either dilated or cystically cavitated. The third and fourth ventricles are within normal limits for size. The cerebral aqueduct is patent. In fact, the lateral ventricles are not frankly dilated except for those areas of cavitary/cystic expansion discussed above. The cerebellar vermis and hemispheres are hypoplastic. The inferior outflow pathway of the fourth ventricle is widened. The right cerebellar hemisphere is somewhat more truncated than the left with thin T2/gradient hypointense rimming along its inferior surface.Pattern of sulcation is appropriate for the presumed gestational age. No definite evidence of any cortical clefting, dysplasia or other migrational anomaly is seen.The fetal spleen appears to be somewhat enlarged, though this is difficult to assess with accuracy as images were tailored for evaluation of the brain.Maternal findings include a subjective paucity of amniotic fluid. Also noted is mild prominence of the maternal renal collecting system which can be physiologic.
1.The cavum septum pellucidum and corpus callosum are identified and appear within normal limits.2.A pattern of largely periventricular abnormalities is identified including areas of cavitation and/or cystic dilatation. Associated periventricular signal abnormality is suggestive of the presence of necrosis and blood product with or without calcification.3.The posterior fossa structures are hypoplastic and, in addition, there are findings to suggest tissue injury and loss within the right cerebellar hemisphere. Prominence of the inferior fourth ventricular outflow pathway may reflect inferior vermian hypoplasia, less likely a mild Dandy-Walker spectrum variant.4.The above findings, and particularly the periventricular abnormalities, in the context of an otherwise normally formed brain, suggest an acquired process. Congenital infection could produce all of the imaging findings noted above. CMV would be the favored agent given the pattern, though other infectious agents are not excluded. Alternately, these abnormalities could be primarily ischemic in nature.