Breast Ultrasound Technique
Screening Ultrasound
Practical Limitations
- Not always covered by insurance
- Time-consuming: approximately 20 minutes
- Operator dependent (handheld)
Automated Whole Breast Ultrasound (AWBU)
- Not operator dependent once tech places breast in slight compression
- Less time-consuming
ACRIN 6666 Study — Key Data
- Incremental cancer detection with supplemental screening whole-breast US: 2–3 per 1000
- PPV3 is markedly low: 6–7% (many false positives)
- ACRIN found slightly higher number of cancers but their population was higher risk
- Recall rate: may be twice as high as screening mammo
- Biopsy rate: may be three times as high
Board Pearl
Can give a BI-RADS 0 for screening US (incomplete assessment) — this is different from diagnostic US.
Reporting Bilateral Screening US
- If completely negative: record one image per quadrant radial/antiradial + one retroareolar image
Scan Orientation
Preferred: Radial/Antiradial
- Aligned with ductal system (centripetal breast anatomy)
- Better suited to breast anatomy
- Preferred orientation for breast US
Alternative: Transverse/Longitudinal (Sagittal)
- Less suited to centripetal breast anatomy
- But familiar from body ultrasound imaging
Malignant Features on US
| Feature | Significance |
|---|---|
| Irregular shape | High suspicion |
| Spiculated/angular/microlobulated margin | High suspicion |
| Marked hypoechogenicity | High suspicion |
| Shadowing | High suspicion |
| Duct extension | High suspicion |
| Echogenic rim (include in measurements) | Represents desmoplastic reaction |
| Vertical orientation (taller than wide; NOT parallel) | High suspicion |
Board Pearl
The echogenic rim = desmoplastic reaction (fibrosis surrounding the tumor). It is included in the measurement of the mass because it represents part of the tumor’s biological extent. Malignant masses are “taller than wide” (vertical orientation, not parallel).
BI-RADS 3 on US (Probably Benign)
Descriptors that qualify for BI-RADS 3 assessment:
- Oval, parallel, circumscribed, hypoechoic, solid mass (likely fibroadenoma)
- Isolated complicated cyst with low-level echoes
- Microlobulated or oval mass composed entirely of microcysts (simple appearing)
US Study Requirements
Mandatory elements:
- Patient name, MRN (or DOB), date, name and location of facility
- Initials of individual performing exam (tech or doctor)
- Breast imaged, clock location, distance from nipple
- Object being imaged
- Transducer orientation
- Can include: depth of breast (retroareolar, anterior/middle/posterior, axillary tail, axilla)
Measurement: Find the largest dimension → measure that AND the perpendicular measurement → find the orthogonal third dimension. Record if palpable.
Spatial Compound Imaging
- Overlaps several different images taken at different angles into one image
- Reduces noise (speckle)
- Improves resolution at the center of the image
- Defines margins better
- But posterior features may become less apparent
Fluid Aspiration Pearls
When aspirating a lesion that looks cystic:
- If aspirate is non-bloody and lesion completely resolves → done
- If aspirate is bloody and lesion disappears → clip it and send fluid to cytology
- If aspirate is purulent → send to microbiology for culture and sensitivity; if lesion doesn’t disappear, need to core and clip it
- Green, yellow, or black fluid from a lesion that disappears → can be discarded (benign)