Neoplasms of the Meninges James G. Smirniotopoulos, MD

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MR Signal and Meningioma Types • Most are Isointense to GM ‣ On both T1W & T2W • Hyperintense to GM on T1W ‣ “Lipoblastic” (Fatty) Meningioma ‣ Hemorrhage into Meningioma • Hypointense on T2W ‣ Fibroblastic ‣ Transitional • Hyperintense on T2W ‣ Meningothelial ‣ “Angioblastic” • Microcystic (“Humid”) Meningioma - Dural Tail [Figure 8] Dural tail: Histology [Figure 9] Figure 9 Dural Tail: Differential Diagnosis • Extraaxial Lesions ‣ Meningioma Most common lesion w/dural tail Most common lesions overall ‣ Schwannoma ‣ Hemangiopericytoma ‣ Sarcoidosis ‣ Dural Lymphoma and metastases ‣ Gumma (syphilis) • Intraaxial Lesions ‣ Pleomorphic Xanthoastrocytoma ‣ Superficial cerebral astrocytoma ‣ GBM (rare) Cavernous Sinus Meningioma [Figure 10] Figure 8 A, B, C & D Meningioma - Dural Tail. The upper right image shows branching hypointensities that may represent flow voids from tumor vessels. Dural Tail • Curvilinear enhancement • “Dural flair” • First reported w/meningioma • First reported to be neoplastic invasion • What is it REALLY? ‣ Thickening of the dura ‣ Vasocongestion of the dura ‣ Edema of the dura Figure 10 A & B Cavernous Sinus Meningioma with extensive dural enhancement along the tentorium. Meningioma CT & MR Features • Mass effect 88% 90% • Extraaxial Location 42% 70% • Broad Dural Attach. 74% 98% • Typical Dense./Intensity 92% 74% • Hyperostosis 10% 14% • Homogeneous 76% 76% • Enhancement 96%(78%) 96%(80%) (Homogeneous) • Meningeal. Enhance (tail) 2% 50% • “Capsule” 14% 68% Neuroradiology 1990;32:467-73. Neuroradiology 1291 Neoplasms of the Meninges
Other Locations for Meningioma • Intraventricular • Orbit ‣ Intraconal ‣ Periorbital • Nasal Cavity Intraventricular: ~ 5% [Figure 11] • Usually Adult • F > M • Usually Lateral Ventricle • Usually Trigone/Atrium • ALWAYS attached to Choroid Plexus • Vascular pedicle from choroid Figure 11 Figure 12 A & B Meningioma – Supplied by branches of the ECA, showing classic spoke-wheel vascularity. Intraventricular Meningioma. Figure 13 Optic Nerve Meningioma Meningioma Arterial Supply • External Carotid 85% • Internal Carotid 63% • Tumor Blush 95% Meningioma – Venous phase, showing persistent and dense tumor blush. Delayed Washout [Figure 14] Meningioma - Angiography – Transit Time [Figure 12] • Blush or Stain ‣ Early arterial ‣ Prominent in VENOUS phase ‣ Capillaries/sm. arterioles ‣ (Too small to see individually) • Venous Filling ‣ Characteristic if delayed ‣ May fill with or before Nl. veins Meningioma - Angiography – Long Transit Time [Figure 13] • Venous Filling (Stattin, 1996) ‣ 170 Meningiomas ‣ Delayed in 136 (80%) ‣ With Nl. vv. In 10 (6%) ‣ Earlier in 24 (14%) ‣ (8 in early arterial phase) • Leeds & Taveras (1969) ‣ EDV in 6/36 (16%) Figure 14 A to E MR Perfusion study, showing delayed washout from meningioma. Courtesy of Dra. Perla Salgado, Mexico City, Mexico. Neoplasms of the Meninges 1292 Neuroradiology
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Neoplasms of the Meninges James G. Smirniotopoulos, MD

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