Can vertebral artery dissection be detected on MRI (Magnetic Resonance Imaging) brain without contrast?

Vertebral Artery Dissection Detection on MRI Brain Without Contrast

Vertebral artery dissection can be detected on MRI brain without contrast, but with limited sensitivity of approximately 60-77% compared to CTA's superior sensitivity of 100%. 1, 2

Diagnostic Capabilities of Non-Contrast MRI/MRA

• Non-contrast MRI brain has several limitations for vertebral artery dissection detection:

  • Lower sensitivity (60-77%) compared to CTA (100%) 1, 2
  • May overestimate stenosis severity in dissections 1
  • Inadequate anatomic definition for treatment planning 1

• MRI techniques that can help identify vertebral artery dissection without contrast:

  • Fat-saturated T1-weighted sequences (best for visualizing intramural hematomas) 1
  • 3D time-of-flight MRA sequences (for luminal assessment) 1
  • Flow-compensated gradient echo sequences 3

Imaging Findings of Vertebral Artery Dissection

When present on MRI/MRA, vertebral artery dissection may show:

• Stenosis (51% of cases) 2
• "String and pearls" appearance (48%) 2
• Arterial dilation (37%) 2
• Arterial occlusion (36%) 2
• Pseudoaneurysm, double lumen, or intimal flap (22% each) 2
• Mural hematoma (specific finding when present) 3

Optimal Imaging Protocol

For suspected vertebral artery dissection:

1. CTA head and neck with IV contrast is the preferred initial test (100% sensitivity) 1, 2
2. MRA with contrast is the second-best option (77% sensitivity) 1, 2
3. MRA without contrast is a reasonable alternative when contrast is contraindicated 4

Important Clinical Considerations

• The entire vertebral artery should be imaged from origin to basilar artery, as dissection can occur anywhere along its course 1
• Adding vessel wall imaging sequences may improve detection of nonstenotic arterial dissection 1
• Follow-up imaging can be performed with non-contrast MRA to avoid radiation exposure 4

Common Pitfalls

• Relying solely on non-contrast MRI/MRA may miss up to 40% of vertebral artery dissections 1, 2
• Non-specific radiographic signs predominate, with no single finding present in the majority of cases 2
• Technique and sequence selection significantly impact sensitivity 1
• Using low-field MRI systems may further reduce detection capability 4

For optimal diagnostic accuracy in suspected vertebral artery dissection, CTA with IV contrast remains the gold standard, but when radiation exposure is a concern or for follow-up imaging, MRA (ideally with contrast) is a reasonable alternative.