Colloid cysts are smooth, round lesions of endodermal origin, typically located at the foramen of Munro in the anterior aspect of the third ventricle. They are usually filled with gelatinous material and cholesterol crystals. These cysts generally occur in adults and account for approximately 1% of all intracranial tumors. Symptoms include headaches, vertigo, memory deficits, diplopia, and behavioral disturbances.Due to the proteinaceous nature of its contents, a colloid cyst is typically hyperdense on T1-weighted magnetic resonance (MR) images.
Also note the arachnoid cyst behind the tectal plate