Clinical question: History arachnoid cyst. Evaluate for change in size. Signs and symptoms: None surveillance imaging. Nonenhanced brain MRI:Examination demonstrates normal anatomical development of brain parenchyma.Unremarkable cerebral cortex, cortical sulci, ventricular system, CSF spaces and brain myelination for age.There is revisualization of a CSF signal intensity extra-axial fluid in the midline under the tentorium without appreciable change since prior head CT examination from 11-23-14. Finding is believed to represent a normal anatomical variation of CSF space however less likely possibility of a small arachnoid cyst cannot be entirely excluded. This finding on axial T2-weighted images measures at 10 x 12 mm in transaxial dimensions.There is normal visualization of signal void in major intracranial arterial branches.There is unremarkable signal intensity of intracranial venous sinuses.Unremarkable calvarium and soft tissues of the scalp.Unremarkable images through the orbits.
1.Unremarkable nonenhanced brain MRI.2.Stable 10 x 12 mm subtentorial midline CSF space prominence likely representing a normal anatomical variation. Remote possibility of a small arachnoid cyst cannot be entirely excluded. 