Introduction to CT scans

A CT scan, or computed tomography scan, is an imaging test that uses X-rays and computer processing to create detailed cross-sectional pictures of the body. It is quick, precise, and widely used in emergency and inpatient settings because it can rapidly detect conditions such as bleeding, fractures, and organ injury.

In interventional neuroradiology, CT is particularly important for assessing conditions affecting the brain and blood vessels, such as haemorrhage or stroke, and in the evaluation of cerebral aneurysms. CT angiography (CTA) involves the injection of intravenous contrast dye to highlight arteries and veins, allowing clinicians to detect aneurysms, vessel narrowing, or arteriovenous malformations with high accuracy. It is often the first-line vascular imaging technique because it is fast, widely available, and non-invasive.

Compared with MRI, CT is usually preferred in urgent cases, such as suspected aneurysmal subarachnoid haemorrhage or acute stroke, because it can be performed rapidly and is excellent at showing fresh blood. MRI, by contrast, offers greater detail of soft tissue and vessel walls without radiation but takes longer, is less available in emergencies, and is more affected by patient movement.

CT scanning has clear advantages: it is quick, precise, and excellent for detecting bleeding and vascular pathology with CTA. Its disadvantages include the use of ionising radiation and the possibility of artefacts, particularly when metal devices such as coils or stents have already been placed, which can obscure detail in follow-up imaging.