Brain imaging

Techniques that provide pictures of the brain; they are used to detect injury or disease and include X-rays, angiography, CT scanning, MRI, PET (positron emission tomography) scanning, and SPECT (single photon emission CT). X-ray films can show changes in the skull caused by a fracture or, rarely, by a brain tumour or aneurysm. Angiography shows up the blood vessels in the brain, and is used to investigate subarachnoid haemorrhage, aneurysms, abnormalities of the blood vessels, and other circulatory disorders. CT scanning gives images of the brain substance; it gives clear pictures of the ventricles (fluid-filled cavities) and can reveal tumours, blood clots, strokes, aneurysms, and abscesses. MRI is especially helpful in showing tumours of the posterior fossa (back of the skull). PET and SPECT scanning are specialized forms of radionuclide scanning that use small amounts of radioactive material to give information about brain function as well as structure. They enable blood flow and metabolic activity in the brain to be measured. Ultrasound scanning is used only in premature or very young babies since ultrasound waves cannot penetrate the bones of a mature skull.