Does Magnetic Resonance Angiography (MRA) use gadolinium as a contrast agent?

Does MRA Use Gadolinium?

Yes, contrast-enhanced MRA (Magnetic Resonance Angiography) typically uses gadolinium-based contrast agents to enhance vascular visualization, though non-contrast MRA techniques are also available. 1

Types of MRA Techniques

Contrast-Enhanced MRA

• Contrast-enhanced MRA is performed with gadolinium, which acts as a paramagnetic contrast agent that:
  • Shortens T1 relaxation time of blood
  • Creates very bright signal intensity in T1-weighted images
  • Provides excellent visualization of the renal arteries and abdominal vasculature 1
  • Offers sensitivities of 90-100% and specificities of 76-94% for detecting renal artery stenosis 1

Non-Contrast MRA Techniques

• Alternative non-gadolinium MRA techniques include:
  • Time-of-flight (TOF) techniques
  • Phase contrast (PC) imaging
  • Steady-state free precession (SSFP) sequences
  • Balanced SSFP (bSSFP) sequences that utilize inherent contrast between blood pool and vessel wall 1

Advantages of Gadolinium-Enhanced MRA

• Higher signal-to-noise ratios compared to non-contrast techniques
• Robustness regardless of blood flow patterns or velocities
• Faster image acquisition allowing evaluation of larger anatomic segments
• Fewer flow-related artifacts compared to older techniques 1
• Less nephrotoxic than iodinated contrast used in CT angiography 1
• Very low rate of allergic reactions (serious reactions <0.01%) 1

Clinical Applications

• Gadolinium-enhanced MRA has widely replaced conventional X-ray angiography for evaluation of:
  • Extracranial vessels
  • Thoracic vessels
  • Abdominal vessels
  • Peripheral vessels 1
• Particularly valuable in patients with impaired renal function who cannot receive iodinated contrast for CTA 1

Safety Considerations

• Gadolinium is cytotoxic alone but safe when combined with a chelating agent 1
• Risk of nephrogenic systemic fibrosis (NSF) in patients with:
  • Acute or chronic severe renal insufficiency (GFR <30 mL/min/1.73m²)
  • Acute renal insufficiency due to hepato-renal syndrome
  • Perioperative liver transplantation period 1
• For high-risk patients, macrocyclic GBCAs are preferred over linear GBCAs 2
• Risk stratification based on eGFR is recommended:
  • Low risk: eGFR >45 mL/min/1.73m²
  • Intermediate risk: eGFR 30-45 mL/min/1.73m²
  • High risk: eGFR <30 mL/min/1.73m² 2

Non-Contrast Alternatives

• For patients who cannot receive gadolinium, non-contrast MRA techniques are available:
  • ECG-gated and pulse-gated breath-hold non-contrast bSSFP-MRA
  • These techniques show good agreement with CTA for thoracic aortic measurements, though with somewhat poorer image quality 1

In summary, while gadolinium-based contrast agents are commonly used in MRA to enhance image quality and diagnostic accuracy, non-contrast MRA techniques are available and continue to improve for patients who cannot receive gadolinium.