What is an angiogram?

What is an Angiogram?

An angiogram is a diagnostic imaging procedure that uses contrast material and specialized X-ray technology to visualize blood vessels, providing detailed images of the vascular system to detect abnormalities such as stenosis, aneurysms, or occlusions. 1

Types of Angiography

Conventional (Catheter) Angiography

• Considered the "gold standard" for vascular imaging 1
• Involves catheter insertion and direct injection of contrast material into blood vessels
• Highest spatial resolution for detecting small vessel abnormalities
• Allows for simultaneous therapeutic intervention
• Disadvantages:
  • Invasive procedure with 0.2-0.3% risk of major adverse events
  • Requires skilled personnel and specialized equipment
  • Exposes patients to ionizing radiation
  • Only visualizes the arterial lumen, not vessel walls 1

CT Angiography (CTA)

• Uses CT scanner with timed contrast injection
• Requires thin-section acquisition timed to coincide with peak arterial enhancement
• Allows 3D reconstructions and reformatting of images
• Can detect bleeding rates as low as 0.3 mL/min 1
• Less invasive than conventional angiography

Magnetic Resonance Angiography (MRA)

• Can be performed using time-of-flight or phase-contrast techniques 2, 3
• No exposure to ionizing radiation
• Can be combined with other MR techniques to assess cardiac function and structure
• Limitations for detecting subtle vascular injuries 1, 4
• Particularly useful when contrast agents present high risk 4

Clinical Applications

Cardiac Angiography

• Evaluates coronary arteries for stenosis, occlusion, or anomalies
• Assesses cardiac function and valve competency 5
• Often combined with intravascular imaging for specific lesion subsets (left main, proximal LAD, in-stent restenosis, calcified arteries) 1

Cerebral Angiography

• Critical assessment of intracranial aneurysms
• Analysis includes aneurysm morphology, neck-to-dome ratio measurements, parent vessel relationships 1
• Can be combined with intraoperative tools like indocyanine green video angiography during surgical procedures 1

Pulmonary Angiography

• "Gold standard" test for defining pulmonary vascular anatomy 5
• Used to identify chronic thromboembolic obstruction, determine surgical accessibility, and rule out other diagnostic possibilities
• In pulmonary angiography, thrombi appear as unusual filling defects, pouches, webs, or bands 5

Retinal Angiography

• Fluorescein or indocyanine green angiography demonstrates alterations in arterial and choroidal flow patterns 5
• Documents extent of retinal vasculature involvement
• Helps differentiate origin and extent of retinal artery occlusions 5

Advantages and Limitations

Advantages

• Provides high-resolution images of blood vessels
• Can detect bleeding as slow as 0.3-0.5 mL/min 1
• Non-invasive options (CTA, MRA) available for screening or initial evaluation
• Allows for therapeutic intervention during the same procedure (conventional angiography)

Limitations

• Conventional angiography is invasive with potential complications
• Exposure to ionizing radiation (conventional and CT angiography)
• Potential adverse reactions to contrast agents
• Limited ability to assess surrounding structures in conventional angiography 5

Potential Pitfalls in Interpretation

• Underestimating stenosis severity due to diffuse disease
• Misinterpreting overlapping vessels as stenosis
• Failing to recognize eccentric lesions
• Not accounting for vessel foreshortening in measurements 1
• False-negative results may occur when the false lumen is not opacified or when the intimal flap is not displayed in profile 5

Angiography remains an essential diagnostic tool in modern medicine, with the specific modality chosen based on the clinical context, suspected pathology, and patient-specific factors. While conventional angiography remains the gold standard for many applications, non-invasive techniques like CTA and MRA continue to advance and provide valuable alternatives in many clinical scenarios.