Brain CT quickly assesses the brain tissue, its membranes, ventricles, blood vessels and skull bones. It is the method of choice after a head injury, when a stroke or bleed is suspected, and when MRI is contraindicated.
- Duration5 min; with contrast 20–30 min
- Contrastif indicated
- Preparationnone (fasting if contrast is used)
- Report20 min – 1 hour
What it shows
- Recent and old haemorrhages
- Ischaemic and haemorrhagic stroke
- Effects of injury: brain contusion and swelling, midline shift, skull fractures
- Benign and malignant tumours, metastases
- Cysts, hydrocephalus
- Aneurysms and arteriovenous malformations (with contrast)
- Inflammation: encephalitis, abscess
- Developmental anomalies, including encephalocele
When it is recommended
- Head injury
- Suspected stroke or bleed, including telling ischaemia from haemorrhage
- Headache, dizziness, speech or movement problems, episodes of loss of consciousness
- Seizures that start suddenly with no obvious cause
- Suspected brain tumour or metastases
- Ongoing symptoms with normal or inconclusive results of other tests
- Contraindications to MRI (pacemaker, metal implants, insulin pump)
Preparation
- If contrast is planned, come on an empty stomach.
Good to know
- MRI is usually better for subtle changes in brain tissue; CT is preferred for injury, acute disturbances of cerebral blood flow and assessing the skull bones.
- Brain vessels can only be assessed on CT with IV contrast; a detailed vessel study is a separate examination, CT angiography of the brain vessels.
General information about CT — safety, contraindications, contrast and what to expect — is on the CT page.