An intraventricular location is relatively rare, accounting for only 2 % of meningiomas, with 80% of these in the lateral ventricles. Despite this, intraventricular meningioma is the most common trigonal mass in the adult. They are thought to form via the infolding of meningeal tissue during the formation of the choroid plexus. Nonenhanced CT typically demonstrates an iso- to hyperdense lesion. Calcification is seen in 20% of cases, with a psammomatous pattern (diffuse, sand-like appearance) most common. Circular, globular, or radial calcification may also be seen. On MRI, lesions are typically hypo- to isointense on T1-weighted images and iso- to hyperintense on T2-weighted images. Lesions classically show intense uniform enhancement on both CT and MR images after injection of contrast media due to their lack of blood-brain barrier.
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