ACR TI-RADS (Thyroid Imaging Reporting and Data System) is a point-based ultrasound system that stratifies a thyroid nodule into one of five risk levels, TR1 (benign) to TR5 (highly suspicious), and pairs each level with a size threshold to decide between no action, follow-up ultrasound, or fine-needle aspiration (FNA). This guide covers what each score means, the scoring chart, malignancy risk, size thresholds, what happens after FNA, and a ready-to-use reporting template.
Calculate a score in seconds: use the ACR TI-RADS calculator (also available in Español and Português), then read on to interpret and report it.
What does a TI-RADS score mean?
The TI-RADS level tells you how suspicious a nodule looks on ultrasound and, together with its size, what to do next. It is a risk-stratification tool, not a diagnosis — only cytology (FNA) or histology confirms cancer. Here is what each level means in plain terms, with the malignancy rates validated on 3,422 nodules in the 2018 ACR TI-RADS analysis.
| Level | Points | What it means | Approx. cancer risk | What happens next |
|---|---|---|---|---|
| TR1 | 0 | Benign | 0.3% | No FNA, no follow-up |
| TR2 | 2 | Not suspicious | 1.5% | No FNA, no follow-up |
| TR3 | 3 | Mildly suspicious | 4.8% | FNA if ≥2.5 cm; follow up if ≥1.5 cm |
| TR4 | 4–6 | Moderately suspicious | 9.1% | FNA if ≥1.5 cm; follow up if ≥1 cm |
| TR5 | ≥7 | Highly suspicious | 35% | FNA if ≥1 cm; follow up if ≥0.5 cm |
So a TI-RADS 2 result is reassuring (about 1 in 65 chance of cancer and no biopsy needed), whereas a TI-RADS 5 result carries roughly a 1-in-3 malignancy risk and usually warrants FNA once it reaches 1 cm. A TI-RADS 4 nodule is intermediate — most turn out benign, but the ~9% cancer risk is high enough to biopsy larger nodules.
How the TI-RADS score is calculated
Assess the nodule in five feature categories. Pick one feature each from composition, echogenicity, shape and margin, and add points for all echogenic foci that apply. Sum the points to get the level.
| Category | Feature | Points |
|---|---|---|
| Composition | Cystic or almost completely cystic | 0 |
| Spongiform* | 0 | |
| Mixed cystic and solid | 1 | |
| Solid or almost completely 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 | 0 |
| Ill-defined | 0 | |
| Lobulated or irregular | 2 | |
| Extrathyroidal extension | 3 | |
| Echogenic foci (add all that apply) | None | 0 |
| Large comet-tail artifact# | 0 | |
| Macrocalcifications | 1 | |
| Peripheral (rim) calcifications | 2 | |
| Punctate echogenic foci$ | 3 |
*Spongiform = predominantly (>50%) small cystic spaces. #Large comet-tail artifact = echogenic focus with V-shaped echoes >1 mm deep. $Punctate echogenic foci are non-shadowing.
Because a nodule that is even mixed cystic-and-solid (1 point) will always gain at least one more point for the echogenicity of its solid component, the lowest score any lesion other than a purely cystic/spongiform TR1 can reach is 2 points — which is why there is no “1-point” category.
FNA and follow-up: size thresholds
The level alone does not decide the biopsy — size does too. FNA is reserved for nodules large enough that a missed cancer would matter, which spares patients unnecessary biopsies of tiny nodules.
| Level | FNA if maximum diameter | Follow-up ultrasound if | Follow-up schedule |
|---|---|---|---|
| TR1 / TR2 | Not recommended | Not recommended | — |
| TR3 | ≥2.5 cm | 1.5–2.4 cm | 1, 3, 5 years |
| TR4 | ≥1.5 cm | 1–1.4 cm | 1, 2, 3, 5 years |
| TR5 | ≥1 cm | 0.5–0.9 cm | Annually for 5 years |
Key rules: nodules <5 mm need no FNA even if TR5. If multiple nodules are present, biopsy the two highest-scoring nodules (not the two largest), and follow no more than four. Report no more than four nodules in total.
Sonographic features explained
- Composition — how solid the nodule is. Cystic and spongiform nodules are almost always benign; solid nodules score highest.
- Echogenicity — brightness of the solid component versus normal thyroid. Marked hypoechogenicity (darker than strap muscle) is the most suspicious.
- Shape — measured on the transverse image. Taller-than-wide (anteroposterior > transverse) suggests infiltrative growth.
- Margin — lobulated/irregular margins and extrathyroidal extension raise concern; a smooth or ill-defined margin does not.
- Echogenic foci — punctate echogenic foci (possible psammomatous microcalcification) are the most worrisome; large comet-tail artifacts are benign colloid.
Not part of the lexicon: Doppler vascularity does not separate benign from malignant (though flow does exclude debris or haemorrhage), a peripheral “halo” is non-specific, and elastography is not included. Benign descriptors such as the uniformly hyperechoic “white knight” and the “giraffe hide” pattern are also outside the scoring system.
Suspicious cervical lymph nodes (biopsy if seen): rounded/globular shape, loss of the echogenic hilum, peripheral rather than hilar flow, cystic change, and punctate echogenic foci.
What counts as nodule growth?
On follow-up, interval enlargement is significant if there is a >20% increase in at least two dimensions with a minimum 2 mm increase, OR a >50% increase in volume. Compare with the oldest available prior study, not just the most recent. If the TI-RADS level rises between scans, repeat the ultrasound the following year.
After FNA: the Bethesda System (2023, 3rd edition)
TI-RADS ends at the decision to biopsy. Once FNA is done, the cytology is reported with the Bethesda System for Reporting Thyroid Cytopathology, whose third edition (2023) gives every case one of six named categories, updated malignancy risks, and management guidance. Knowing these categories lets you close the loop between your ultrasound report and the pathology result.
| Category | Diagnosis | Approx. risk of malignancy | Usual management |
|---|---|---|---|
| I | Nondiagnostic | ~13% (5–20%) | Repeat US-guided FNA |
| II | Benign | ~4% (2–7%) | Clinical and sonographic follow-up |
| III | Atypia of undetermined significance (AUS) | ~22% (13–30%) | Repeat FNA, molecular testing or lobectomy |
| IV | Follicular neoplasm | ~30% (23–34%) | Molecular testing or diagnostic lobectomy |
| V | Suspicious for malignancy | ~74% (67–83%) | Surgery (lobectomy or thyroidectomy) |
| VI | Malignant | ~97% | Surgery |
The 2023 edition uses a single name per category, aligns terminology with the 2022 WHO Classification of Thyroid Neoplasms, splits AUS into “nuclear atypia” and “other,” and adds chapters on molecular testing (e.g., Afirma, ThyroSeq) and imaging. Reported risks vary with whether NIFTP is counted as malignant.
TI-RADS vs other risk-stratification systems
ACR TI-RADS is one of several ultrasound systems. Comparative studies show broadly similar cancer-detection performance; the ACR system’s additive, size-adjusted design is aimed particularly at reducing unnecessary FNA of low-risk nodules.
| System | Type | Categories |
|---|---|---|
| ACR TI-RADS (2017) | Additive point score | TR1–TR5 |
| EU-TIRADS (2017) | Pattern-based | 1–5 |
| K-TIRADS (2016/2021) | Pattern-based | 1–5 |
| ATA guidelines (2015) | Pattern-based | 5 sonographic patterns |
Thyroid ultrasound reporting template (TI-RADS)
A structured template keeps reports consistent and makes scoring auditable:
INDICATION: TECHNIQUE: Ultrasound of the thyroid and adjacent soft tissues. FINDINGS Thyroid size / echotexture: Estimated number of nodules >=1 cm: Nodule #[1-4] Location: [right / left / isthmus]; [upper / mid / lower] Size: __ x __ x __ cm (three orthogonal planes) Composition: [cystic 0 / spongiform 0 / mixed 1 / solid 2] Echogenicity: [anechoic 0 / hyper- or isoechoic 1 / hypoechoic 2 / very hypoechoic 3] Shape: [wider-than-tall 0 / taller-than-wide 3] Margin: [smooth 0 / ill-defined 0 / lobulated-irregular 2 / ETE 3] Echogenic foci: [none 0 / comet-tail 0 / macro 1 / peripheral 2 / punctate 3] TI-RADS points: __ Level: [TR1-TR5] Recommendation: [no follow-up / follow-up US in __ / US-guided FNA] IMPRESSION: [Summary + TI-RADS level and management of the highest-scoring nodule(s)]
Downloadable aids: sonographer’s worksheet, TI-RADS atlas, and the reporting template.
Test yourself: TI-RADS scoring examples
Score each nodule, then check with the TI-RADS calculator.
Example 1 — what is the TI-RADS level?
Show answer
Solid 2 + hypoechoic 2 + wider-than-tall 0 + smooth margin 0 + punctate echogenic foci 3 = 7 points → TR5 (highly suspicious), malignancy risk ~35%.
Example 2 — what is the TI-RADS level?
Show answer
Solid 2 + hypoechoic 2 + wider-than-tall 0 + ill-defined margin 0 + no echogenic foci 0 = 4 points → TR4 (moderately suspicious), malignancy risk ~9%.
Example 3 — what is the TI-RADS level?
Show answer
Mixed cystic and solid 1 + hypoechoic 2 + wider-than-tall 0 + ill-defined margin 0 + punctate echogenic foci 3 = 6 points → TR4 (moderately suspicious), malignancy risk ~9%.
Example 4 — what is the TI-RADS level?
Show answer
Solid 2 + isoechoic 1 + wider-than-tall 0 + smooth margin 0 + no echogenic foci 0 = 3 points → TR3 (mildly suspicious), malignancy risk ~4.8%.
Frequently asked questions
What does a TI-RADS score mean?
A TI-RADS score is an ultrasound risk level from TR1 (benign) to TR5 (highly suspicious) that estimates how likely a thyroid nodule is to be cancer and guides whether it needs a biopsy or follow-up. It is a risk estimate, not a diagnosis.
What is a TI-RADS 2 (TR2) nodule?
A TR2 nodule scores 2 points and is “not suspicious,” with an approximate malignancy risk of 1.5%. No FNA or follow-up ultrasound is recommended.
What is a TI-RADS 4 (TR4) nodule? Is it cancer?
A TR4 nodule scores 4 to 6 points and is “moderately suspicious,” with about a 9% chance of malignancy — so most TR4 nodules are benign. FNA is recommended when it measures 1.5 cm or larger.
What is a TI-RADS 5 (TR5) nodule?
A TR5 nodule scores 7 points or more and is “highly suspicious,” with roughly a 35% malignancy risk. FNA is recommended once it reaches 1 cm.
When does a thyroid nodule need FNA on ACR TI-RADS?
FNA size thresholds are: TR3 at 2.5 cm or larger, TR4 at 1.5 cm or larger, and TR5 at 1 cm or larger. TR1 and TR2 nodules are not biopsied, and nodules under 5 mm are not biopsied regardless of level.
What is the difference between TI-RADS and Bethesda?
TI-RADS grades the nodule on ultrasound to decide whether to biopsy it. The Bethesda System grades the FNA cytology afterwards into six categories with their own malignancy risks. TI-RADS is imaging; Bethesda is pathology.
References
- Tessler FN, Middleton WD, Grant EG, et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee. J Am Coll Radiol. 2017;14(5):587-595. PMID: 28372962.
- Tessler FN, Middleton WD, Grant EG. Thyroid Imaging Reporting and Data System (TI-RADS): A User’s Guide. Radiology. 2018;287(1):29-36. PMID: 29558300.
- Hoang JK, Middleton WD, Farjat AE, et al. Reduction in Thyroid Nodule Biopsies and Improved Accuracy with ACR TI-RADS. Radiology. 2018;287(1):185-193. PMID: 29498593.
- Middleton WD, Teefey SA, Reading CC, et al. Comparison of Performance Characteristics of ACR TI-RADS, K-TIRADS, and ATA Guidelines. AJR Am J Roentgenol. 2018;210(5):1148-1154. PMID: 29629797.
- Grant EG, Tessler FN, Hoang JK, 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. PMID: 26419308.
- Tappouni RR, Itri JN, McQueen TS, et al. ACR TI-RADS: Pitfalls, Solutions, and Future Directions. RadioGraphics. 2019;39(7):2040-2052. PMID: 31603734.
- Ali SZ, Baloch ZW, Cochand-Priollet B, et al. The 2023 Bethesda System for Reporting Thyroid Cytopathology. Thyroid. 2023;33(9):1039-1044. PMID: 37427847.
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