CV Junction Meningioma MRI

A 40 y o female with progressive lower limb weakness. 

On admission MRI Brain and Cervical spine screening done.

This MRI sagittal T2w images and Post contrast fat sat T1w images shows an extra axial solid signal intensity lesion, iso intense on T2w images at foramen magnum causing foramen magnum stenosis and significant cord compression. Intense homogeneous enhancement of lesion on post contrast with dural tailing.

Imaging diagnosis : CV Junction / Foramen Magnum Meningioma.

Dense calcified 'Involuted sclerotic' / 'Psammomatous' Meningioma MRI

Non contrast CT

MRI T1, FLAIR, T2, Dwi, T2*GRE

Non contrast CT shows a left frontal ovoid well demarcated mass at the floor of anterior cranial fossa, isodense to bone. On MRI, lesion show uniform low signals on all pulse sequences including T2*GRE implies to dense calcification. Marked perilesional vasogenic odema in adjacent left frontal lobe white matter on FLAIR.
MR Spectroscopy, going to be non contributory in this case as lesion is densely calcified.


Histopathology report: 

Description of finding: The resected specimen consist of an irregular, firm, bosselated, tan-white nodule with an attached dura mater on one side. The specimen fixed in buffered 10% formaldehyde and decalcified. Paraffin-embedded sections stained with H n E stain. The tissue consisted primarily of densely packed hyalinized collagen bundles. Major portion virtually acellular, occasional small nests of uniform meningothelial cells. Few areas of whorllike arranged collagen fibers.

- 'Psammomatous' variety of Meningioma.

Dense calcified Meningioma

Syn: 'Involuted sclerotic' Meningioma, 'Psammomatous' Meningioma.

Involuted sclerotic meningioma is a distinct subtype of benign meningioma that lack the classic appearance and manifestation of typical meningothelial meningiomas.
A classic meningioma on CT is a relatively hyper attenuating, extra axial mass broad based to Dura with a smooth or lobulated outline that enhances homogeneously on post contrast study. Most common histopathological variety of typical meningioma is fibrous meningioma shows parallel and interlacing bundles of spindle-like cells embedded in a matrix of collagen and reticulin on Histopathology.
Whereas a sclerotic meningiomas demonstrate whorl formation around sclerotic vessels, with tumor cells demonstrating glial fibrillary acidic protein expression. Due to dense calcification these masses are iso dense to bony calvarium on CT, contrast enhanced studies are non contributory as enhancement if any is difficult to interpret in the back ground of dense calcification. On MRI, lesion is low signal intensity on all pulse sequences, poor or partial enhancement on post contrast. Dural tailing on post contrast and focal hyperostosis of adjacent bony calvarium of a typical meningioma are absent.

Differential diagnosis for an extra axial calcified mass at the cerebral convexity without dural tailing or bone reaction should include osteoma.

Similar case: Psamomatous-meningioma

Reference : Best Cases from the AFIP Involuted Sclerotic Meningioma, Radiographics.

Meningioma MR Spectroscopy

MR Spectroscopy is a noninvasive method for bio chemical evaluation of intra canial mass lesions in vivo. Meningioma has specific spectral pattern which can help in differentiating meningioma a most common non glial tumour from Glioma.

The common pattern found in meningioma is average or slightly high Cho peak is more common than very high levels of Cho. Choline reflects membrane turnover and correlates with malignancy.
Absent or very low NAA implies to non neuronal origin of mass.
Very low or absent Cr.
Variable amounts of lactate.
Most important, double or tipple peaks of Ala centered at 1.47 ppm which inverts on the long TE sequence (Reference AJNR 20:882–885, May 1999)

In this case a well circumscribed extra axial dura based lobulated mass in right parietal region along inter hemisphere fissure on right side of the falx. Punctate T2 flow void of vessels seen at the interphase of mass and adjacent compressed right parietal lobe support extra axial location of mass. Mass is isointense to cortical grey matter. Few t2 hyperintense foci of perilesional odema in adjacent compressed brain parenchyma best depicted on flair.
On sigle voxel MR Spectroscopy performed with 2x2cm voxel placed over the mass in right parietal region with water suppression of 98%. No intra venous contrast given.
Spectral waveform obtained at short TE of 35 ms from right to left;
Triple peaks from 1.2 to 1.6ppm corresponds to alanine.
No peak of NAA at 2.01ppm
No peak of Cr at 3.02ppm
Choline peak at 3.2ppm
Manitol peak at 3.8ppm, manitol is used as part of treatment to reduce cerebral odema.

Imagingwise diagnosis: Falcine Meningioma.

Related post : Multiple intracranial meningiomas