What Is Angiography?

Angiography is a medical imaging technique that produces visual representations of blood vessels, both arteries and veins, by introducing a contrast agent into the vascular system and capturing the resulting enhancement with X-ray, computed tomography, magnetic resonance, or ultrasound imaging. The term derives from the Greek words for vessel and to write, reflecting its essential purpose: creating a readable image of the vascular tree. Angiography is used to detect, characterize, and guide treatment of a wide range of vascular conditions including stenoses, occlusions, aneurysms, arteriovenous malformations, and tumors with abnormal vascularity.

The technique spans both diagnostic and interventional roles. In its diagnostic form, angiography maps the anatomy and patency of vessels. In its interventional form, the same catheter access used to inject contrast is extended to deliver balloons, stents, coils, or embolic agents directly to the target site, a practice broadly known as interventional radiology.

Imaging Technique

Conventional catheter-based angiography, or digital subtraction angiography (DSA), involves inserting a thin catheter into an artery or vein, threading it under fluoroscopic guidance to the region of interest, and injecting iodinated contrast medium while acquiring rapid-sequence X-ray images. A pre-injection mask image is digitally subtracted from the contrast-enhanced images, removing background bone and soft tissue and leaving only the opacified vasculature. According to Radiology Info, the patient education resource of the Radiological Society of North America, modern flat-panel detector systems achieve spatial resolutions below 0.2 mm, sufficient to depict small perforating arteries in the brain and coronary side branches. Radiation dose is managed through pulsed fluoroscopy, beam collimation, and real-time dose tracking, in compliance with the as-low-as-reasonably-achievable (ALARA) principle.

Types of Angiography

Several modality-specific and site-specific variants of angiography have developed around distinct clinical questions. Coronary angiography evaluates the coronary arteries for stenosis and is performed in catheterization laboratories before revascularization decisions. Cerebral angiography, performed through a femoral or radial approach with the catheter advanced into the carotid and vertebral arteries, is used to characterize intracranial aneurysms, arteriovenous malformations, and stroke-related occlusions. Pulmonary angiography maps the pulmonary vasculature and was historically used to diagnose pulmonary embolism before CT angiography became the standard method. CT angiography (CTA) and MR angiography (MRA) are less invasive alternatives that reconstruct vascular anatomy from volumetric scans; CTA uses iodinated contrast and ionizing radiation, while MRA commonly uses gadolinium contrast agents or exploits the magnetic properties of flowing blood without contrast. A technical summary of fluoroscopic angiography protocols is available through the NCBI Bookshelf StatPearls collection.

Diagnostic and Interventional Uses

Angiography provides both anatomical and functional information. Stenosis severity in coronary angiography is quantified by measuring the percent reduction in vessel diameter at the site of narrowing, often supplemented by fractional flow reserve measurements acquired with a pressure-sensing guidewire. In peripheral vascular disease, angiography maps the distribution of occlusive disease in the iliac, femoral, and tibial arteries to plan endovascular or surgical reconstruction. Neurointerventional teams use cerebral angiography to guide catheter-delivered coil packing and flow-diverting stent placement in intracranial aneurysm treatment. Oncological applications include tumor embolization, in which angiography identifies feeding vessels that are then selectively occluded to reduce blood supply. According to EuroIntervention's review of coronary fluoroscopy, conventional invasive angiography remains the foundation of modern catheter-based therapy despite the growth of non-invasive imaging alternatives.

Applications

Angiography has applications across a wide range of clinical specialties and research domains, including:

• Cardiology, for coronary artery disease diagnosis and guidance of percutaneous coronary intervention
• Neurology and neurosurgery, for cerebrovascular disease assessment and endovascular stroke treatment
• Oncology, for transarterial chemoembolization of liver tumors
• Peripheral vascular disease management, including limb salvage procedures
• Trauma surgery, for identifying and embolizing bleeding vessels following injury