The short answer
ACR TI-RADS gives points for five ultrasound features of a thyroid nodule. The point total sets a level from TR1 to TR5, and the level plus the nodule's size decides between biopsy, repeat scans, or neither.
TI-RADS was built to cut down on biopsies of nodules that turn out to be harmless, not to find every cancer.
The level on its own is only half a recommendation; the nodule's largest measurement supplies the other half.
More than one TI-RADS exists, so it is worth asking which system produced the number on your report.
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The full explanation.
An adding-up system, not a verdict
TI-RADS stands for Thyroid Imaging Reporting and Data System. The version used across much of the United States is ACR TI-RADS, published by the American College of Radiology in 2017.
It works like a scorecard. The radiologist looks at a nodule, awards points for what they see, adds the points, and reads off a level.
Nothing in that process involves a diagnosis. The whole system runs on the appearance of an image.
The five things being scored
Every ACR TI-RADS score is built from the same five feature groups, with the points fixed in advance:
- Composition — cystic or spongiform 0, mixed cystic and solid 1, solid 2
- Echogenicity — anechoic 0, hyperechoic or isoechoic 1, hypoechoic 2, very hypoechoic 3
- Shape — wider than tall 0, taller than wide 3
- Margin — smooth or ill-defined 0, lobulated or irregular 2, spread outside the thyroid 3
- Echogenic foci — none or large comet-tail artifacts 0, macrocalcifications 1, rim calcifications 2, punctate specks 3
When a feature cannot be judged, the chart tells the radiologist which value to assume. An undetermined composition is treated as solid, and undetermined echogenicity as isoechoic.
The total becomes a level
| Points | Level |
|---|---|
| 0 | TR1 |
| 2 | TR2 |
| 3 | TR3 |
| 4 to 6 | TR4 |
| 7 or more | TR5 |
The bands are not equal. TR1, TR2 and TR3 each cover a single total, while TR4 spans three and TR5 has no upper limit.
Size supplies the other half
A level on its own is not a recommendation. ACR pairs each level with size thresholds, and the pairing is the actual output of the system:
| Level | Aspiration | Follow-up ultrasound |
|---|---|---|
| TR1 | None | None |
| TR2 | None | None |
| TR3 | 2.5 cm or more | 1.5 to 2.4 cm, at 1, 3 and 5 years |
| TR4 | 1.5 cm or more | 1.0 to 1.4 cm, at 1, 2, 3 and 5 years |
| TR5 | 1.0 cm or more | 0.5 to 0.9 cm, every year for 5 years |
Read the bottom row carefully. Even the highest level recommends nothing at all below 0.5 cm. That is a design choice, not an oversight.
What the system was built to reduce
The ACR is direct about the problem it set out to solve. Thyroid nodules are very common, most are benign, and many are biopsied to find the small number that are not.
ACR convened committees in 2012 with three tasks: advise on nodules found by accident, agree a shared vocabulary for describing them, and build a risk system on top of that vocabulary. The first two arrived in 2015 and TI-RADS followed in 2017.
A later review by members of the same committee reported that ACR TI-RADS has higher specificity than other risk systems, and reduces unnecessary biopsies of benign nodules by between 19.9% and 46.5% compared with them.
The system is measured by how many needless procedures it avoids, not only by what it finds.
Where TI-RADS is weakest
Three honest limits are worth carrying into an appointment.
First, the features are judged by eye. The same committee's review names reducing variation between readers as an ongoing challenge.
Second, the trade-off is real. One multicenter series of 3,422 nodules included 352 cancers. Risk rose steadily from TR1 to TR5, as the chart intends. A later analysis of that same series found 40 of those cancers sat in the group the chart sends for neither aspiration nor follow-up, and 16 of the 40 measured 1 cm or more.
Third, TI-RADS is not one thing. Korean and European groups publish their own versions, and the American Thyroid Association has separate guidance. A number without a system name is ambiguous.
When a report gives no level
Plenty of thyroid ultrasound reports still describe nodules in words alone. That is not a failing, but it does leave you with more to ask:
- Which system, if any, was used?
- What size is the nodule, in its largest dimension?
- Which specific features were described?
- Is there an earlier scan to compare against?
- Who decides whether a needle sample is needed, and when?
Related reading
The most common level is covered in What Does TI-RADS 4 Mean. For what comes next, see Thyroid Nodule on Ultrasound: What Now and What Does Bethesda Category Mean on a Thyroid Biopsy.
Sources
- American College of Radiology — TI-RADS
- ACR TI-RADS diagnostic ultrasound reporting template
- Tessler FN et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee. J Am Coll Radiol. 2017
- Hoang JK, Middleton WD, Tessler FN. Update on ACR TI-RADS: Successes, Challenges, and Future Directions. AJR Am J Roentgenol. 2021
- Middleton WD et al. Multiinstitutional Analysis of Thyroid Nodule Risk Stratification Using the ACR TI-RADS. AJR Am J Roentgenol. 2017
- Middleton WD et al. Analysis of Malignant Thyroid Nodules That Do Not Meet ACR TI-RADS Criteria for Fine-Needle Aspiration. AJR Am J Roentgenol. 2021
Words to know
Tap any term to see what it means.
Common questions
Does a TI-RADS level tell me if I have thyroid cancer?
No. It is a structured estimate of risk from an ultrasound image. Only cells taken by fine-needle aspiration and read by a pathologist can say what a nodule is.
Why does the report say no follow-up for a suspicious-sounding nodule?
Because size counts. Even at TR5, the ACR chart recommends neither aspiration nor follow-up below 0.5 cm. Small nodules are common and mostly harmless.
Is every TI-RADS the same?
No. ACR TI-RADS is one of several systems, alongside ones from Korean and European groups and separate guidance from the American Thyroid Association. They use different points and thresholds.
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Sources last checked: 2026-07-21 what this meansLast updated: 2026-08-10Next planned review: 2027-07-21
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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