Centred on the posterior third ventricle in the midline, inseparable from the pineal, is a 31 x 21 x 21 cystic mass with a fluid/fluid level with supernatant effect with blood product in the dependent portion, and T1 hyperintense anterior compartment. Thickened septations lie within the cyst, and do not enhance. Apart from some subtle capsule enhancement, there is no definite enhancing component.
The mass causes compression of the cerebral aqueduct-the degree of hydrocephalus has been decreased by placing a right ventricular shunt catheter since the earlier CT scan. The third ventricle anterior to the mass is distended and contains water density CSF. The vein of Galen and internal cerebral veins are displaced superiorly.
No other intracranial mass lesions, or abnormal enhancement is shown.