BI-RADS 3 Classification Does Not Apply to Thyroid Ultrasound
BI-RADS (Breast Imaging Reporting and Data System) is a classification system exclusively designed for breast imaging and should never be used for thyroid ultrasound evaluation. 1
Correct Thyroid Nodule Classification System
For thyroid nodules, you must use TI-RADS (Thyroid Imaging Reporting and Data System), not BI-RADS:
TI-RADS 3 (Mildly Suspicious) Management
For TI-RADS 3 thyroid nodules:
- Fine needle aspiration (FNA) is recommended only if the nodule measures ≥1.5 cm 2
- For nodules <1.5 cm classified as TI-RADS 3, surveillance without FNA is appropriate when high-risk clinical factors are absent 3
- Follow-up ultrasound should be performed in 6-12 months for smaller TI-RADS 3 nodules 2
Initial Workup Algorithm
When evaluating any thyroid nodule:
- Obtain dedicated high-resolution thyroid ultrasound with central neck evaluation 3
- Measure TSH to assess thyroid function 3, 4
- Apply complete TI-RADS risk stratification assessing composition (solid vs cystic), echogenicity, margins, shape, and calcification patterns 4
High-Risk Clinical Factors That Lower FNA Threshold
Consider FNA for nodules <1.5 cm if any of these are present: 3
- History of head and neck irradiation
- Family history of thyroid cancer
- Age <15 years
- Male gender
- Suspicious cervical lymphadenopathy
Critical Pitfall to Avoid
Do not confuse BI-RADS (breast) with TI-RADS (thyroid) - these are completely separate classification systems for different organs. BI-RADS category 3 indicates "probably benign" breast findings with <2% malignancy risk requiring short-term breast imaging follow-up 1, but this terminology and framework do not translate to thyroid evaluation.