Breast Ultrasonography

USG Breast Basics - Probing Principles

• Indications:

  • Palpable lump (esp. < 40 yrs, pregnant/lactating).
  • Adjunct to mammography (dense breasts, lesion workup).
  • Intervention guidance (biopsy, aspiration).

• Probe: High-frequency linear array (7.5-15 MHz); ↑frequency = ↑resolution, ↓penetration.

• Technique:

  • Patient supine, ipsilateral arm raised.
  • Radial/Antiradial scanning (nipple as clock center).
  • Document: clock face, distance from nipple, depth, size.
  • Optimize: gain, Time Gain Compensation (TGC), focal zone, depth.

• Normal USG Anatomy (Superficial to Deep):

  • Skin → Subcutaneous fat → Mammary (glandular) zone (Cooper's ligaments echogenic) → Retromammary fat → Pectoralis muscle → Ribs (posterior acoustic shadowing).

⭐ Cooper's ligaments appear as echogenic, curvilinear structures providing breast support, well-visualized on USG.

BI-RADS USG - Lexicon Lowdown

Standardized system for reporting breast ultrasound findings, guiding management. Categories 0-6.

• Shape & Orientation:
  • Shape: Oval (often benign), Round, Irregular (suspicious).
  • Orientation: Parallel ("wider-than-tall" - often benign), Not parallel ("taller-than-wide" - suspicious).
• Margin:
  • Circumscribed (often benign).
  • Not circumscribed: Indistinct, Angular, Microlobulated, Spiculated (all suspicious).
• Echo Pattern & Posterior Features:
  • Echo Pattern: Anechoic, Hypoechoic, Isoechoic, Hyperechoic, Complex (cystic/solid).
  • Posterior Features: Enhancement (often benign), Shadowing (often suspicious), Combined, None.
• Calcifications & Associated Features:
  • Calcifications: Macrocalcifications; Microcalcifications (in mass/outside mass).
  • Associated Features: Duct changes, Skin changes (retraction/thickening), Edema, Vascularity (present/absent, location).

⭐ BI-RADS 3 lesions imply a <2% risk of malignancy; initial short-interval follow-up (e.g., 6 months) is crucial.

Benign Lesions USG - Friendly Phantoms

Benign lesions show non-suspicious USG features: (📌 Mnemonic: WOW - Wider than tall, Oval, Well-circumscribed). Typically oval/round shape, parallel orientation, and well-circumscribed margins. (BI-RADS USG)

• Simple Cyst (BI-RADS 2)
  • Anechoic, round/oval, circumscribed
  • Posterior acoustic enhancement
  • No internal vascularity
• Fibroadenoma (BI-RADS 2/3)
  • Commonest benign solid tumor.
  • Homogeneous, hypoechoic/isoechoic
  • Oval, circumscribed, parallel
  • Thin echogenic capsule; popcorn calcification (involuting)
• Lipoma (BI-RADS 2)
  • Isoechoic to fat/hyperechoic
  • Oval, circumscribed, compressible
• Galactocele
  • Variable echogenicity; fat-fluid level
  • Posterior enhancement
• Intramammary Lymph Node (BI-RADS 2)
  • Oval/reniform, hypoechoic cortex < 3mm
  • Echogenic fatty hilum

⭐ A "breast within a breast" USG appearance strongly suggests a hamartoma (fibroadenolipoma).

Malignant Lesions USG - Sinister Shadows

• Shape & Orientation: Irregular, not parallel to skin; taller-than-wide (AP diameter > transverse) highly suspicious.
• Margins: Spiculated (hallmark), angular, microlobulated, ill-defined.
• Echo Pattern: Marked hypoechogenicity (vs. fat), heterogeneous internal echoes.
• Posterior Acoustic Features: Shadowing ("sinister shadow") common; can be combined or rarely enhanced.
• Microcalcifications: Punctate echogenic foci, often without shadowing; suspicious if clustered/pleomorphic.
• Ductal Involvement: Extension into ducts, branch pattern.
• Vascularity (Doppler): Increased internal vascularity, penetrating vessels.
• Associated Signs: Thickened/retracted Cooper's ligaments, skin dimpling/retraction, lymphedema. Axillary node: cortical thickness >3mm, absent fatty hilum.

⭐ Taller-than-wide orientation is a strong predictor of malignancy, indicating growth across tissue planes rather than along them.

• Primary modality for women < 30 years, pregnant, or lactating.
• Key to differentiate cystic (anechoic, posterior enhancement) from solid masses.
• BI-RADS US standardizes reporting and malignancy risk assessment.
• "Taller-than-wide" shape is a highly suspicious sign of malignancy.
• Posterior acoustic shadowing often indicates malignancy; enhancement suggests benign.
• Essential for guiding interventions like biopsies and aspirations.
• Doppler US assesses vascularity, aiding characterization (benign vs. malignant).