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.
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.
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.
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.
Frequently Asked Questions
What does EU-TIRADS 5 mean and should I be worried?
EU-TIRADS 5 means at least one high-risk ultrasound feature was identified, such as an irregular shape or margin, microcalcifications, or markedly hypoechoic appearance. The malignancy risk ranges from 26 to 87 percent. FNA biopsy is recommended for EU-TIRADS 5 nodules 1.0 cm or larger. Prompt evaluation is important but many EU5 nodules are still benign.
Can I use the EU-TIRADS calculator if my report is from a European hospital?
Yes. The EU-TIRADS calculator implements the European Thyroid Association 2017 classification, which is the standard system used across most European institutions. Select the ultrasound pattern described in your report and enter the nodule size.
How do I know which TI-RADS system my radiologist used?
Check the report for the specific label. If it says ACR TI-RADS or TR1 through TR5 with point totals, the ACR system was used. If it says EU-TIRADS or EU1 through EU5 with pattern descriptions, the European system was used. If unclear, ask your radiologist which system they applied.