MR Spectroscopy in Meningioma

MR spectroscopy may provide additional information in cases in which the differential diagnosis
of tumors by neuroimaging is difficult. Cho reflects membrane turnover, correlates with malignancy in astrocytic tumors, and forms high peaks in meningioma. The most common proton spectrum found in meningiomas is a high Cho peak with low or absent NAA and Cr and variable amounts of lactate. Most important, an unusually high ratio of Ala to Cr has been found in meningiomas because of the high Ala and low Cr content, and this is a relatively specific finding for meningioma. Alanine is seen as doublet centered at 1.47 ppm and inverts on the long-TE sequence.

Reference- AJNR Am J Neuroradiol 20:882–885, May 1999

Intraventricular Meningioma-MRI

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.