Breast Imaging
What the exam tests
Breast imaging questions emphasize modality selection, BI-RADS lexicon and management, screening performance, and breast cancer staging. Expect mammography (including digital breast tomosynthesis), ultrasound, MRI, and image-guided biopsy.
Core rules
- Screening mammography is for asymptomatic patients; diagnostic mammography adds views and is used for symptoms or an abnormal screening result.
- BI-RADS 0 is incomplete; 1-2 benign; 3 probably benign (<2% malignancy) with short-interval follow-up; 4 suspicious (4A low, 4B moderate, 4C high); 5 highly suggestive (>95%); 6 known biopsy-proven malignancy.
- Suspicious calcifications include pleomorphic, linear, and fine-linear branching forms; segmental or linear distribution raises concern.
- Ultrasound is a first adjunct for a palpable mass or mammographic asymmetry, especially in younger patients. MRI screening is for high-risk patients, not average-risk screening.
Worked example
A 56-year-old woman has screening mammography showing a 1.5-cm group of pleomorphic calcifications in a segmental distribution in the upper outer quadrant, without an associated mass. Reasoning: pleomorphic morphology and segmental distribution are suspicious; BI-RADS 3 is inappropriate. The next step is stereotactic core biopsy with marker placement, and the lesion is categorized at least BI-RADS 4B, often 4C. If biopsy shows DCIS, surgical planning and margin assessment follow.
Traps
Calling a one-view asymmetry a mass without orthogonal views; assigning BI-RADS 3 to pleomorphic calcifications; assuming a negative ultrasound excludes calcification-based malignancy; and offering MRI screening to average-risk women.
Key points
- Use BI-RADS categories to drive management, not just describe findings.
- Pleomorphic or linear branching calcifications warrant tissue sampling.
- Tomosynthesis improves screening specificity but does not replace diagnostic workup.
- MRI is the most sensitive screening test in high-risk women.