4 month old female, ex-32 weeker, with history of hypothalamic, tectal and fourth ventricle masses and congenital hydrocephalus for follow up. There is interval resolution of pneumocephalus within the frontal horns and the previously identified post-surgical changes. There is a right frontal approach ventriculostomy catheter placement, with tip near the foramen of Monro just to the right of midline. There is significant interval decrease in dilatation of the lateral ventricles. The third and lateral ventricles appear normal in size. There is interval decrease in the prominence of subarachnoid space along the medial occipital lobes bilaterally. There is mild prominence of the subarachnoid spaces along the bilateral frontal lobes. There are foci of susceptibility artifact in the ventricles, particularly the occipital horns and right temporal horn.There is interval enlargement in T2 hypointense mass along the right lateral aspect of the vermis (image 20, series 901) with associated subtle diffusion restriction, which measures approximately 18 x 15 mm, previously 11 x 7 mm. There is no associated enhancement. There is again distortion of the contour of the posterior right cerebellum, with asymmetric prominence of the extra-axial space posteriorly.There is redemonstration of a subtle mass along the ventral aspect of the lower tectum resulting in aqueductal obstruction. This lesion measures 7 mm in AP dimension, previously 6 mm, likely without significant interval change allowing for differences in technique. There is no corresponding enhancement. The previously seen small thumb-like soft tissue mass just anterior and superior to the mammillary bodies projecting into the third ventricle along the floor is not as well delineated due to the resolved third ventricle dilatation, but is grossly similar to the prior study. There is also no corresponding enhancement in this location.
1. Redemonstration of previously identified hypothalamic region, tectal, and vermian masses with interval enlargement in the vermian mass, but grossly stable size of the hypothalamic region and tectal masses. No corresponding enhancement.2. Right frontal approach ventriculostomy catheter, which is unchanged in position. Interval decrease in size of the lateral ventricles with normal size of the third ventricle. Fourth ventricle remains partially effaced and aqueduct obstructed.3. Focal prominence of extra-axial space posterior to the right cerebellum, which may relate to right cerebellar dysplasia and/or mega cisterna magna vs. retrocerebellar cyst. 