 There is redemonstration of significant prominence of extra-axial space along the cerebral hemispheres bilaterally. This is most notable anteriorly along the right frontal lobe, where there is suggestion of a more focal collection with differential flow characteristics with respect to a more superficial thin subdural collection. The more superficial collection which is subtly FLAIR hyperintense with respect to CSF again measures up to 6-7 mm in greatest thickness, with the oval area of CSF signal intensity measuring approximately 3.6 x 5.6 cm in greatest axial dimensions x 3.7 cm CC. Overall, this collection appears progressed since prior CT exams, with more comparable comparison on sagittal imaging where it currently measures up to 3.6 cm in greatest thickness on 401/21, compared to previous 3.1 cm on 8/29/2016 and 3.2 cm on 9/9/2016. There remains moderate mass effect upon the underlying parenchyma with focal concavity of the frontal lobe on the sagittal images.On the left, for ease of reference as the subarachnoid vessels are visualized at this level on the previous noncontrast CT exams better defining the subdural collection margins, the left lateral subdural collection measures up to 14 mm in greatest thickness on 501/16, compared to previous 6 mm. This collection is also slightly greater than CSF signal intensity on FLAIR imaging, with only subtle flattening of the left frontal lobe parenchyma. There is trace midline shift to the right measuring 2 mm. There is redemonstration of moderate dilatation of the lateral and third ventricles, although similar in caliber to the more recent CT exams. Previously, third ventricle measured 6 mm transverse, and it now measures 14 mm transverse. The fourth ventricle is normal size. Sagittal images do not demonstrate any significant posterior fossa crowding, although patency of the cerebral aqueduct cannot be confirmed on this exam.The previously seen bilateral frontal periventricular CSF signal intensity cysts are again seen, nearly resolved on the left, but increased size on the right compared to the more remote MRI. The right-sided cyst now measures 1.6 cm AP x 1.5 cm CC, compared to previous 1.2 x 0.8 cm. There remains mild flattening of the lateral aspect of the right frontal horn. Previous abnormal signal with susceptibility along the supracerebellar cistern is no longer appreciated, consistent with resolved blood products.There is a minimal residual cavum septum pellucidum et vergae. The basal cisterns remain patent. There is no diffusion abnormality. Myelination appears relatively appropriate for corrected age except for slight decreased prominence of intrinsic T1 signal along the anterior aspect of the anterior limb of the internal capsules.Normal flow-voids are demonstrated in the major intracranial vascular structures. The midline structures and craniocervical junction are within normal limits.There is redemonstration of a midline fluid-filled cleft palate. There is diffuse fluid opacification of mastoid air cells and middle ears. There is suggestion of hypertelorism.
1. Compared to more recent CT imaging, there has been slight interval progression of the right-sided extra-axial collection, with more focal oval component along the anterior right frontal lobe resulting in moderate mass effect. This is of CSF signal intensity although with differential flow characteristics the remainder of the right-sided collection, and most likely represents an acquired arachnoid cyst.2. No significant interval change in the more superficial component of the subdural collection, slightly greater than CSF signal intensity on FLAIR images.3. Interval increased size of left lateral subdural collection, also slightly greater than CSF on FLAIR imaging.4. Essentially near resolved left and increased size of right frontal periventricular cysts which are favored to represent a benign entity such as connatal or subependymal cyst.5. Redemonstration of moderate dilatation of lateral and third ventricles which is progressed since the remote prior MRI. Normal sized fourth ventricle. Consideration could be made for CSF flow imaging to evaluate patency of the cerebral aqueduct.6. Interval resolution of previously seen blood products along the supracerebellar cistern.