What are the indications for MRI (Magnetic Resonance Imaging) breast screening?

MRI Breast Screening Indications

MRI breast screening should be performed annually for women with genetics-based increased risk (including BRCA mutation carriers and their untested first-degree relatives), those with prior chest radiation therapy before age 30, and those with a calculated lifetime risk of 20% or more. 1

High-Risk Populations Requiring Annual MRI Screening

Genetic Risk Factors

• BRCA1/BRCA2 mutation carriers:
  • Begin MRI screening at age 25
  • Add annual mammography at age 30 1
  • For BRCA1 carriers under 40, mammography adds minimal benefit when MRI is used regularly 1
  • For BRCA2 carriers, mammography remains important at all ages 1

Radiation Exposure History

• Prior chest/mantle radiation therapy:
  • Begin MRI screening at age 25 or 8 years after completion of radiation therapy, whichever is later 1
  • Applicable to those who received radiation before age 30 1
  • Cancer risk increases substantially approximately 8 years after therapy 1

Risk Assessment Based

• Lifetime risk ≥20% based on risk assessment models 1
• Untested first-degree relatives of known BRCA mutation carriers 1

Additional Indications for MRI Screening

Personal History of Breast Cancer

• Women with personal histories of breast cancer and dense breast tissue 1
• Women diagnosed with breast cancer before age 50 1
• MRI sensitivity in this population is 85% versus 23% for mammography 1
• Cancer detection rates with MRI range from 10-29 cancers/1,000 in this population 1

Other High-Risk Conditions

• Lobular Carcinoma In Situ (LCIS):
  • MRI increases cancer detection to levels similar to other high-risk populations 1
• Atypical hyperplasia:
  • Consider MRI, especially if other risk factors are present 1

Performance of MRI in Screening

• Sensitivity of MRI ranges from 71-100% versus 16-40% for mammography in high-risk populations 1
• In BRCA mutation carriers, MRI sensitivity is 77-91% compared to 33-40% for mammography 1
• Specificity of MRI ranges from 81-97% 1
• False positive rates are higher with MRI compared to mammography, especially in initial (prevalent) screening rounds 2

Important Considerations for Implementation

Technical Requirements

• Dedicated breast coil
• Radiologists experienced in breast MRI interpretation
• Capability to perform MRI-guided needle sampling/wire localization 1

Age-Related Considerations

• Below age 50, the number of mammographic examinations needed to find an MRI-occult cancer is approximately 1427 3
• Women over 50 years without BRCA mutations may have slightly more benefit from adding mammography, but also experience more false positives 3

Clinical Outcomes

• 97% of incident cancers detected through MRI screening in BRCA carriers are Stage 0 or 1 4
• Long-term follow-up shows very low distant recurrence rates for cancers detected through MRI screening 4

Common Pitfalls and Caveats

1. False positives: MRI has a higher false-positive rate than mammography, which can lead to unnecessary biopsies and patient anxiety
2. Availability and expertise: High-quality breast MRI requires specialized equipment and experienced radiologists
3. Cost implications: MRI is significantly more expensive than mammography
4. Gadolinium concerns: Contrast-enhanced MRI requires gadolinium, which has potential safety concerns in certain populations

MRI breast screening should be targeted to women at significantly elevated risk of breast cancer, as the evidence does not support its use in average-risk women.