EXTRA-AXIAL MASSES( TYPICAL MENINGIOMA )

BY:

DR. HASSAN ALQARNIR1 RADIOLOGY RESIDENT

SAUDI BOARD

Top Differential Diagnoses

• Meningioma• Dural metastasis• Granuloma (TB, sarcoid)• Idiopathic hypertrophic pachymeningitis• Extramedullary hematopoiesis• Hemangioma, dura/venous sinuses

MeningiomaHyperostosis, cortical irregularity, calcification

Metastases, MeningealMultiple > solitary lesionsOften known extracranial primary neoplasm

Tuberculosis• Abnormal CXR, lab values• Travel history to endemic areas,

immunocompromised

Hypertrophic Pachymeningitis• localised inflammatory thickening of

the dura

Extramedullary HematopoiesisPatients with chronic anemia or marrow depletionMultiple > solitary

Diagnosis :

Meningioma

Meningioma • Most common extra-axial neoplasm of adults and accounts for 15% of

all intracranial neoplasms, second only to gliomas in overall prevalence.

• The peak age of presentation is 50 to 60 years. For both intracranial (2:1) and intraspinal (4:1) meningiomas,

• Females are more commonly affected.

• Because the tumor is hormonally sensitive, it may increase in size during pregnancy.

• Multiple tumors (up to 9% of all cases) are associated with neurofibromatosis.

Pathology

• Arises from arachnoid cap cells with some probable contribution from dural fi broblasts and pial cells.

• It is believed that intraventricular meningiomas arise from arachnoidal cap cell rests buried within the choroid plexus.

Clinical Presentation

• Most common signs/symptoms– < 10% of all meningiomas are symptomatic– Symptoms depend on tumor site• Convexity/parasagittal = seizures, hemiparesis• Basisphenoid, diaphragma sellae = visual field defects• Cavernous sinus = cranial nerve deficit(s)• Frontal = anosmia

Imaging Features• Best diagnostic clue

– Dural-based enhancing mass → cortical buckling, trapped CSF/vessels in "cleft" between tumor and brain

• Location– Supratentorial (90%)

• Parasagittal/convexity (45%), sphenoid ridge (15-20%)• Olfactory groove (5-10%), parasellar (5-10%)• Other (5%): Intraventricular, optic nerve sheath (ONSM), pineal region• Rare: Intraparenchymal without dural attachment

– Infratentorial (8-10%): CPA most common– Extradural (mostly intraosseous, calvaria) > 2%– Extracranial (head/neck)

• Most common: Paranasal sinuses• Less common: Nasal cavity, parotid, skin

– Multiple meningiomas: Seen in 1-9% of cases

CT Findings • NECT

– Sharply circumscribed smooth mass abutting dura• Hyperdense (70-75%), isodense (25%)

– Hypodense (1-5%), fat density (rare lipoblastic subtype)• Calcified (20-25%)

– Can be diffuse, focal, sand-like ("psammomatous")– "Sunburst," globular, rim patterns– Calcification correlates with slow growth in asymptomatic meningiomas

• Necrosis, cysts, hemorrhage (8-23%)– Trapped CSF pools, cysts in adjacent brain common– Peritumoral hypodense vasogenic edema (60%)– Bone CT

• Hyperostosis, irregular cortex, ↑ vascular markings

• CECT– > 90% enhance homogeneously, intensely

• CTA– May be helpful prior to DSA, embolization– Delineates arterial supply, venous drainage

Axial CECT in a 26-year-old pregnant woman with sudden visual loss shows an enhancing suprasellar mass (white solid arrow).

Axial CECT in a patient with primary optic nerve sheath meningioma shows marked enhancement along the left optic nerve, described as a "tram-track" sign (black solid arrow).

Axial CECT shows multiple well-delineated, right-sided extraaxial masses (white solid arrow) that were moderately hyperdense on NECT (not shown) and enhance strongly.

MR Findings• T1WI

– Typically iso- to slightly hypointense with cortex– Necrosis, cysts, hemorrhage (8-23%)– Look for gray matter "buckling"

• T2WI– Variable ("sunburst" pattern may be evident)– 8-23% of intratumoral cysts (common; can be almost microcystic),

hemorrhage (rare)– Best sequence for

• Visualizing CSF/vascular cleft between tumor, brain (80%)• Identifying vascular flow voids (80%)• Predicting "hard" meningioma at surgery (hypointense)

• FLAIR– Hyperintense peritumoral edema, dural tail

• DWI– DWI, ADC maps for TM variable in appearance– Lower ADC in MM and AM compared to TM

• T1WI C+– > 95% enhance homogeneously, intensely– Dural tail (35-80% of cases) nonspecific

• Other neoplasms (schwannoma, adenoma, metastases), nonneoplastic dural-based masses

– En plaque: Sessile thickened enhancing dura• MRV

– Evaluate sinus involvement• MRS

– Elevated levels of alanine at short TE• Triplet-like spectral pattern at 1.3-1.5 ppm (overlapping of Ala, Lac)• Elevated Glx alfa/glutathione

Angiographic Findings

– "Sunburst" or radial appearance• Dural vessels supply lesion core• Pial vessels may be parasitized, supply periphery

– Prolonged vascular "stain"– Venous phase vital to evaluate sinus involvement

Thank you