What is the best initial screening test for brain aneurysms (cerebral aneurysms) in individuals with a family history of brain aneurysms?

Best Screening Test for Brain Aneurysms in Individuals with Family History

MRA head is the ideal initial screening test for individuals with a family history of brain aneurysms due to its high sensitivity, lack of radiation exposure, and noninvasive nature. 1, 2

Evidence-Based Screening Approach

First-Line Screening Test

• MRA head without contrast is recommended as the first-line screening test with:
  • Pooled sensitivity of 95% and specificity of 89% 1
  • No radiation exposure, making it suitable for repeated screenings 2
  • Ability to obtain diagnostic information without IV contrast 1
  • Particularly effective when performed on 3T scanners, which increases diagnostic accuracy for aneurysms <5mm in size 1, 2

Alternative First-Line Option

• CTA head with IV contrast can be considered if MRA is unavailable or contraindicated:
  • High sensitivity (>90%) for aneurysm detection 1
  • Fast acquisition time 2
  • Better for detecting aneurysms adjacent to bony structures 1
  • Limitations include radiation exposure and decreased sensitivity for aneurysms <3mm 1

Who Should Be Screened

• Individuals with ≥2 first-degree relatives with intracranial aneurysms or subarachnoid hemorrhage 1
• Patients with autosomal dominant polycystic kidney disease (ADPKD), especially those with a first-degree relative with history of aneurysm 1
• Higher risk in families with history of hypertension, smoking, and female sex 1

Screening Protocol

• Begin screening at age 16-18 years 3
• Continue screening until age 65-70 years 3
• After initial negative screen, repeat screening every 5 years 3
• Even after two negative screens, continued surveillance is warranted as de-novo aneurysms can develop 3

Limitations and Pitfalls

• MRA limitations:

  • Decreased sensitivity for aneurysms <3mm (45% of missed aneurysms in studies were <3mm) 1
  • Vessel loops and infundibular origins can lead to false-positives 1, 2
  • May require confirmation with DSA if findings are equivocal 1

• CTA limitations:

  • Radiation exposure limits repeated use 2
  • Decreased sensitivity for aneurysms adjacent to osseous structures 1
  • Less effective for aneurysms <3mm 1

Risk Factors for Positive Screening

• Smoking (odds ratio 2.7) 3
• History of previous aneurysms (odds ratio 3.9) 3
• Familial history of aneurysms (odds ratio 3.5) 3

Important Considerations

• The yield of screening remains substantial even after more than 10 years of follow-up and two initial negative screens 3
• Aneurysms have been identified in 5% of individuals screened before age 30 years 3
• Risk of rupture is not completely eliminated with screening, as de-novo aneurysms can develop and rupture between screening intervals 3
• Digital Subtraction Angiography (DSA) remains the reference standard but is not recommended for initial screening due to its invasive nature and potential complications 1

Follow-up of Detected Aneurysms

• For untreated aneurysms, follow-up with the same imaging modality on which the aneurysm was initially found 1
• For treated aneurysms, MRA is superior for coiled aneurysms while CTA is superior for clipped aneurysms 1

By implementing this evidence-based screening approach, the morbidity and mortality associated with aneurysmal subarachnoid hemorrhage can be significantly reduced in high-risk individuals with a family history of brain aneurysms.