Meningiomas are dural-based,
well-circumscribed tumors which sometimes displace and compress the spinal cord.
Spinal meningiomas are mostly found in the thoracic spine (80%),
followed by cervical spine.
Location in the lumbar spine is the rarest.
They are most commonly located posterolaterally,
except in cervical spine where they are usually anterolaterally/anteriorly placed.
They are best depicted on magnetic resonance imaging (MRI) with the intravenous injection of gadolinium-based contrast agent.
The main protocol at our department is T1-weighted images (T1-WI),
T2-weighted images (T2-WI) and post-contrast T1-weighted images in axial and sagittal planes.
Meningiomas appear isointense/slightly hypointese to grey matter on T1-WI,
isointense/slightly hyperdense to grey matter on T2-WI,
with homogenous post-contrast enhancement.
'Dural tail' sign is often seen.
When calcified,
they show low signal on all sequences and low contrast-enhancement.
Rare malignant variants have variable appearance.
Other imaging modalities are less sensitive for meningioma imaging.
If MRI cannot be performed,
contrast-enhanced computed tomography (CT) is the modality of choice as it shows meningiomas as vividly homogenously enhancing lesions.
Non-contrast-enhanced CT is less sensitive for depicting spinal meningeomas as they appear isodense or slightly hyperdense to grey matter.
Sensitivity increases if they contain calcifications or if there is hyperostosis of underlying bone.
Meningiomas are rarely seen on plain films unless they have calcifications,
an indirect sign can also be bone erosions or localized widening of the spinal canal.
Spinal meningioma primary differential diagnosis are spinal schwannomas and neurofibromas.
Those tumors do not show signs of calcification,
they are more commonly placed anteriorly and they tend to be multiple.
Schwannomas and neurofibromas may have low-enhancing central areas on contrast-enhanced images,
they do not have the 'dural tail' sign or the broad dural base and are more commonly forming the dumbbell apperance with the widening of neural foramina.
Nerve sheath tumors are usually hyperintense to the spinal cord on T2-WI,
whereas meningiomas usually are isointense or slightly hyperintense to the spinal cord on T2-WI.