What is the difference between an angiogram and angiography?

Angiogram vs Angiography: Understanding the Difference

An angiogram is the actual image or set of images produced during an angiography procedure, while angiography refers to the medical imaging technique or procedure itself that visualizes blood vessels using contrast agents.

Key Differences

Angiography

• Refers to the medical imaging procedure or technique
• Involves injecting contrast material into blood vessels
• Can be performed using different imaging modalities:
  • X-ray (conventional angiography)
  • CT (CT angiography/CTA)
  • MRI (MR angiography/MRA)
  • Ultrasound (Doppler ultrasound)

Angiogram

• The actual image or set of images produced during angiography
• The diagnostic result/output of the procedure
• Used by clinicians to evaluate vascular structures

Technical Aspects of Different Angiography Methods

Conventional X-ray Angiography

• Considered the "gold standard" for vascular imaging 1
• Involves catheter insertion and direct injection of contrast
• 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 1
  • Requires skilled personnel and specialized equipment
  • Exposes patient 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 1
• Requires 3D reconstructions and reformatting of images 1
• Can detect bleeding rates as low as 0.3 mL/min 1
• Advantages:
  • Less invasive than conventional angiography
  • Faster procedure time
  • Visualizes surrounding structures
• Disadvantages:
  • Higher radiation dose than conventional angiography 1
  • Limited resolution for vessels smaller than 2mm 2

MR Angiography (MRA)

• Uses magnetic resonance imaging with or without contrast
• Can be performed using time-of-flight or phase-contrast techniques 3
• No exposure to ionizing radiation
• Can be combined with other MR techniques to assess cardiac function, structure, and viability 1
• Disadvantages:
  • Time-consuming procedure
  • Limited for detecting subtle vascular injuries 1
  • Artifacts can affect image quality 4
  • Contraindicated in patients with certain implants

Clinical Applications

Coronary Artery Evaluation

• Conventional angiography remains the reference standard for coronary artery disease 1
• CTA is increasingly used for non-invasive coronary assessment
• MRA is developing but still has limitations for coronary imaging 1

Cerebrovascular Assessment

• CTA and MRA are both considered equivalent for cervical arterial injuries 1
• MRA without IV contrast may be limited by artifacts and resolution 1
• Conventional angiography remains the reference standard for detecting low-grade vascular injuries 1

Gastrointestinal Bleeding

• Angiography can detect GI bleeding at rates as low as 0.5 mL/min 1
• Allows for therapeutic intervention with transarterial embolization 1
• CTA can detect bleeding rates as slow as 0.3 mL/min 1

Important Considerations

When to Choose Conventional Angiography

• When therapeutic intervention might be needed simultaneously
• For detection of small vessel abnormalities
• When highest spatial resolution is required
• For definitive diagnosis when non-invasive methods are inconclusive 1

When to Choose Non-invasive Angiography (CTA/MRA)

• For initial screening or evaluation
• In patients with contraindications to invasive procedures
• When radiation exposure is a concern (MRA preferred)
• For follow-up evaluations of known vascular disease

Common Pitfalls

• Mistaking an angiogram (the image) for angiography (the procedure)
• Assuming all angiography methods provide equivalent information
• Underestimating the limitations of non-invasive techniques
• Failing to consider the clinical context when selecting the appropriate angiography method

By understanding the differences between an angiogram and angiography, clinicians can better communicate about vascular imaging and select the most appropriate diagnostic approach for their patients.