Angiography

Angiography refers to any imaging modality which visualises arteries. Angiography can be performed with CT, MR, or with fluoroscopy.

Conventional angiography

Conventional angiography, sometimes called simply angiography, is the oldest form of angiography. A catheter is inserted into a vessel, through which contrast is ejected. Fluoroscopy is used to capture the movement of contrast through the vessel. This technique is used in invasive coronary angiography.

Digital subtraction angiography

Digital subtraction angiography (DSA) is a modern form of invasive angiography. It's performed similarly as conventional angiography. The digital subtraction part occurs when the computer digitally subtracts the image of before the contrast was applied from the image after the contrast was applied. As such, structures which were identical before and after contrast application is removed from the image, leaving only the structures which weren't identical, which are the blood vessels as contrast passes through.

DSA is the gold standard for the diagnosis of intracranial aneurysms.

CT angiography

CT angiography (CTA) refers to using a CT scan and iodine contrast to visualise arteries. CT angiography is widely used and possibly the most frequently used angiographic technique.

Indications

• Pulmonary embolism - called CT pulmonary angiography
• Coronary artery disease - called coronary CT angiography
• Ischaemic stroke
• Renal artery stenosis
• Peripheral artery disease

MR angiography

MR angiography (MRA) refers to using an MR scan to visualise arteries. This can be achieved with gadolinium contrast, or without, due to some modern MR techniques. The earliest MR technique to allow for non-contrast angiography was time of flight (TOF), but nowadays many other techniques exist as well.

MR angiography is usually used instead of CT angiography when it's important to avoid ionising radiation or iodinated contrast material, for example in case of pregnancy and children.‎