TI-RADS in Radiology: Standardized Thyroid Nodule Risk Stratification

Introduction
The Thyroid Imaging Reporting and Data System (TI-RADS) is a standardized ultrasound-based classification system used to assess the malignancy risk of thyroid nodules. Developed by the American College of Radiology (ACR), TI-RADS assigns points based on ultrasound features, guiding clinicians on when to recommend fine needle aspiration (FNA) or follow-up.
It improves reporting consistency, facilitates clear communication between radiologists and clinicians, and reduces unnecessary biopsies.

TI-RADS Scoring Principle
Each thyroid nodule is evaluated across five ultrasound categories:

1. Composition
2. Echogenicity
3. Shape
4. Margin
5. Echogenic foci

Points from each category are summed to determine the TI-RADS level (TR1–TR5), which corresponds to malignancy risk.

TI-RADS Categories and Risk Stratification

TI-RADS Level	Points	Risk of Malignancy	Recommendation
TR1 – Benign	0	~0%	No FNA or follow-up
TR2 – Not Suspicious	2	~2%	No FNA
TR3 – Mildly Suspicious	3	~5%	FNA if ≥ 2.5 cm; follow-up if ≥ 1.5 cm
TR4 – Moderately Suspicious	4–6	~10–20%	FNA if ≥ 1.5 cm; follow-up if ≥ 1 cm
TR5 – Highly Suspicious	≥7	~35%+	FNA if ≥ 1 cm; follow-up if ≥ 0.5 cm

Ultrasound Feature Scoring

• Composition:
  • Cystic/spongiform: 0 points
  • Mixed cystic-solid: 1 point
  • Solid: 2 points
• Echogenicity:
  • Anechoic: 0
  • Isoechoic/hyperechoic: 1
  • Hypoechoic: 2
  • Very hypoechoic: 3
• Shape:
  • Wider-than-tall: 0
  • Taller-than-wide: 3
• Margins:
  • Smooth: 0
  • Ill-defined: 0
  • Lobulated/irregular: 2
  • Extra-thyroidal extension: 3
• Echogenic foci:
  • None/large comet-tail: 0
  • Macrocalcifications: 1
  • Peripheral (rim) calcifications: 2
  • Punctate echogenic foci: 3

Procedure in Practice

1. Perform a high-resolution thyroid ultrasound, evaluating both lobes and isthmus.
2. Assign scores for each category based on the most suspicious nodule feature.
3. Sum points to determine TI-RADS category.
4. Recommend follow-up interval or FNA as per guidelines.

Advantages of TI-RADS

• Standardizes reporting
• Improves interobserver agreement
• Reduces unnecessary FNAs
• Allows risk-based patient management

Limitations

• May under-call risk in rare aggressive variants (e.g., poorly differentiated carcinoma)
• Less validated in pediatric population
• Requires familiarity with scoring to avoid errors

Recent Updates & Future Directions

• AI-assisted ultrasound for automated TI-RADS scoring
• Integration with elastography to refine risk stratification
• Longitudinal tracking in follow-up to monitor nodule changes

Key Takeaways

• TI-RADS is an essential tool for thyroid nodule evaluation in radiology.
• Accurate scoring and adherence to biopsy criteria improve patient outcomes.
• Familiarity with ultrasound features is critical for correct classification.

References

1. Tessler FN, et al. ACR TI-RADS: An Ultrasound Risk Stratification System for Thyroid Nodules. Radiology. 2017;284(1):92–101.
2. Grant EG, et al. Thyroid Ultrasound Reporting Lexicon: White Paper of the ACR TI-RADS Committee. J Am Coll Radiol. 2015;12(12 Pt A):1272–1279.
3. Middleton WD, et al. Comparison of ACR TI-RADS and ATA Guidelines for Thyroid Nodule Risk Stratification. AJR Am J Roentgenol. 2018;210(5):1148–1154.