Characteristics

• Neoplastic causes: Brain metastases are the most common neoplastic intracerebral lesion. They are found in up to 24% of all patients that die from cancer, and represent 20–30% of all brain tumours in adults.

• Infective causes: For example, cerebral abscesses, granulomata.

• Vascular causes: Multiple lesions of varying age are seen in multi-infarct dementia.

• Inflammatory causes: Demyelinating plaques can be seen as multiple low density lesions on CT, predominantly in the periventricular deep white matter.

• Traumatic causes: Contusions are frequently multiple after head trauma.

Clinical features

• Depends on the underlying pathology.

• See solitary lesions.

Radiological features

• Contrast is taken up in tumours, inflammatory granulation tissue or areas of damage to the blood–brain barrier. Melanoma and adenocarcinoma metastases may appear hyperdense prior to contrast.

• Calcification in malignant tumours is uncommon but, if present, suggests an adenocarcinoma. Calcification following granulomatous infection in not uncommon.

• Haemorrhage into metastases occurs infrequently, and when present suggests hypervascular tumours such as melanoma or hypernephroma.

• A follow-up CT performed two weeks after a traumatic event makes multiple contusions more conspicuous.