Neuroradiology

Glioblastoma multiforme

primitive, infiltrating astrocytoma representing the most malignant grading within the spectrum of neuroglial tumours, characterized by the presence of mitoses, necrosis, vascular proliferation, nuclear and cytoplasmic pleomorphism. Less malignant types are anaplastic astrocytoma and astrocytoma.

Glioblastoma is the most common supratentorial neoplasm of the adult and constitutes approximately 15-20% of all intracranial tumours and nearly half of the cerebral gliomas.

Its peak incidence is in the sixth decade and there is a 3/2 male to female ratio.

Clinical signs and symptoms are related to location and size. Seizures, focal neurological deficits, aphasia and progressive signs of raised intracranial pressure may be found. The prognosis is poor with a median survival of approximately 12 months.

The most common locations are the frontal and temporal lobes but more than one lobe can be involved; a characteristic location is in the corpus callosum with a "butterfly" bihemispheric spread in the white matter. Leptomeningeal and dural involvement is quite common when the tumour is cortical or superficial and meningeal dissemination via the CSF is not uncommon.

The tumour is usually diagnosed when it has reached the size of a well delineated large mass with necrosis, extensive white matter oedema and, occasionally, haemorrhages; in the early phases of its growth the tumour may simply be manifested as a slight modification of the white matter signal on MR.

Radiologically, the CT and MR scans show the typical inhomogeneous "multiforme" appearance that gives the name to the lesion. Usually, a central hypodensity surrounded by an irregular isodense highly enhancing rim is found. Diffuse hypodensity of the surrounding white matter with the appearance of vasogenic oedema is almost invariably on associated feature.

On MR (Fig.1) the same inhomogeneous appearance is found with T1 hypointensity and T2 isohyperintensity, with possible paramagnetic effects due to previous haemorrhages of different ages. Prominent vessels with flow void may be found; nonhomogeneous enhancement is marked and the associated signs of mass effect with herniations are seen.

Angiography, when performed, shows newly formed abnormal vessels with fistulae and early draining veins that may sometimes resemble an arteriovenous malformation. A marked tumour blush is also present.

GS

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Fig.1

a, b. MR, T2-weighted and proton density-weighted images. Hyperintense haemorrhagic butterfly glioblastoma occupies the anterior third of the corpus callosum extending bilaterally towards the white matter of the frontal lobes. c, d. MR, T1-weighted coronal images, without and with gadolinium injection. Enhancement of the periphery of the tumour and of the ventricular ependyma.
Glioblastoma multiforme, Fig.1 (a)
Glioblastoma multiforme, Fig.1 (b)
Glioblastoma multiforme, Fig.1 (c)
Glioblastoma multiforme, Fig.1 (d)