Brain tumour. Magnetic resonance imaging (MRI) scan of a coronal section of the brain of a 47-year-old patient with a large meningioma brain tumour (white, centre left). Meningiomas (meningeal tumours) are slow-growing benign (non-cancerous) brain tumours that form on the meninges, the membranous layers surrounding the brain and spinal chord. This meningioma has been calcified (hardened by the deposition of mineral salts). It affects the right parasellar region of the patient's brain, and originates from the right posterior clinoid process (PCP) of the sphenoid bone. Although meningiomas rarely turn cancerous, they can still cause significant symptoms due to the pressure that their growth puts on the brain beneath it. The exact symptoms depend on the area of the brain affected, and this patient experiences vision problems. This is a T1-weighted MRI scan under gadolinium injection.