European Thyroid Association · 2017

EU-TIRADS Calculator

Classify a thyroid nodule using the EU-TIRADS pattern-based system. Select the ultrasound pattern that best matches the nodule, enter its size, and get the category with a biopsy recommendation.

1Select the ultrasound pattern

Choose the single pattern that best describes the nodule. If any high-risk feature is present, select EU-TIRADS 5 regardless of other features.

No nodule found (normal examination)EU1

Pure cyst or entirely spongiformEU2

Oval, smooth, isoechoic or hyperechoic — no high-risk featuresEU3

Oval, smooth, mildly hypoechoic — no high-risk featuresEU4

At least one high-risk feature: irregular shape/margin, microcalcifications, or markedly hypoechoicEU5

2Nodule size

cm — maximum diameter

Malignancy risk

—

Select a pattern above

Recommendation

Select a pattern to see the recommendation.

Looking for the ACR system? Use the ACR TI-RADS Calculator instead.

Educational use only. This calculator implements the EU-TIRADS (2017) classification by the European Thyroid Association. It is not endorsed by the ETA and is not a substitute for professional clinical judgment. Full disclaimer.

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This calculator implements the EU-TIRADS classification system published by the European Thyroid Association (ETA) in 2017. Unlike the ACR TI-RADS point-based system, EU-TIRADS uses a pattern-based approach: select the ultrasound pattern that best matches the nodule, enter its size, and get the category with a biopsy or follow-up recommendation.

How EU-TIRADS Works

EU-TIRADS classifies thyroid nodules into five categories based on their overall ultrasound appearance rather than adding points from individual features. The presence of any single high-risk feature (irregular shape or margins, microcalcifications, or marked hypoechogenicity) is enough to classify a nodule as EU-TIRADS 5, regardless of other features.

EU-TIRADS Categories

Category	Pattern	Malignancy Risk	FNA Threshold
EU1	Normal (no nodule)	—	—
EU2	Benign (pure cyst, spongiform)	~0%	—
EU3	Low risk (oval, smooth, iso/hyperechoic)	2–4%	2.0 cm
EU4	Intermediate risk (mildly hypoechoic, oval, smooth)	6–17%	1.5 cm
EU5	High risk (any high-risk feature)	26–87%	1.0 cm

EU-TIRADS vs ACR TI-RADS

The key difference is methodology: ACR TI-RADS adds points from five independent features, while EU-TIRADS classifies by the dominant ultrasound pattern. Both are validated and widely used, but in different regions. EU-TIRADS is standard across Europe; ACR TI-RADS dominates in the United States. For a detailed comparison, see our EU-TIRADS vs ACR TI-RADS guide.

For clinicians
EU-TIRADS 5 is triggered by any single high-risk feature, making it more sensitive but less specific than ACR TR5 (which requires 7+ accumulated points). Consider this when comparing reports across systems or transferring patients internationally.

For patients
If your report uses EU-TIRADS categories, the logic is similar to ACR TI-RADS but the numbers are not directly interchangeable. Ask your doctor which system was used and what the recommended next step is for your specific nodule.

Source

Based on: Russ G, Bonnema SJ, Erdogan MF, et al. European Thyroid Association Guidelines for Ultrasound Malignancy Risk Stratification of Thyroid Nodules in Adults: The EU-TIRADS. Eur Thyroid J. 2017;6(5):225-237. This calculator is an independent educational reference and is not endorsed by the ETA.