terican

Last verified · v1.0

Calculator · health

Acr Ti Rads Calculator (Thyroid Nodule Risk Stratification)

Stratify thyroid nodule malignancy risk with the ACR TI-RADS calculator. Enter ultrasound features to receive a TR1–TR5 score and size-based biopsy recommendations.

FreeInstantNo signupOpen source

Inputs

TI-RADS Total Score (TR1=0, TR2=2, TR3=3, TR4=4-6, TR5≥7)

—

Explain my result

0/3 free

Get a plain-English breakdown of your result with practical next steps.

TI-RADS Total Score (TR1=0, TR2=2, TR3=3, TR4=4-6, TR5≥7)—points

The formula

How the
result is
computed.

ACR TI-RADS Calculator: Thyroid Nodule Risk Stratification

The ACR TI-RADS calculator (Thyroid Imaging Reporting and Data System) provides a standardized, evidence-based method for stratifying malignancy risk in thyroid nodules identified on ultrasound. Published by the American College of Radiology in 2017 and refined through subsequent multicenter validation studies, TI-RADS assigns numerical point values across five distinct ultrasound feature categories. The cumulative score maps to one of five risk levels — TR1 through TR5 — each paired with specific management recommendations that depend on nodule size. This approach replaces subjective, ad-hoc biopsy decisions with reproducible, threshold-driven clinical guidance.

The TI-RADS Scoring Formula

The total TI-RADS score is the arithmetic sum of five category scores:

TI-RADS Score = Pcomp + Pecho + Pshape + Pmargin + ∑Pfoci

The first four categories each contribute the point value of their single dominant feature. The fifth category — echogenic foci — is additive: a nodule may simultaneously display macrocalcifications, rim calcifications, and punctate foci, and all applicable values are summed independently.

Category 1 — Composition (Pcomp)

Composition describes the internal architecture of the nodule. Purely cystic and spongiform nodules carry zero risk points; increasingly solid nodules carry higher scores.

  • Cystic or almost completely cystic: 0 pts
  • Spongiform (>50% microcystic spaces): 0 pts
  • Mixed cystic and solid: 1 pt
  • Solid or almost completely solid: 2 pts

Category 2 — Echogenicity (Pecho)

Echogenicity compares the nodule’s brightness to surrounding thyroid parenchyma. Lower echogenicity correlates with higher malignancy probability.

  • Anechoic: 0 pts
  • Hyperechoic or isoechoic: 1 pt
  • Hypoechoic: 2 pts
  • Very hypoechoic (darker than adjacent strap muscles): 3 pts

Category 3 — Shape (Pshape)

Shape is assessed on the transverse plane, measured parallel to the skin surface. A taller-than-wide orientation indicates growth perpendicular to tissue planes, a feature strongly associated with malignancy.

  • Wider-than-tall: 0 pts
  • Taller-than-wide: 3 pts

Category 4 — Margin (Pmargin)

Margin characterizes the nodule border. Lobulated or irregular margins suggest infiltrative growth, while extra-thyroidal extension signals locally aggressive disease.

  • Smooth: 0 pts
  • Ill-defined: 0 pts
  • Lobulated or irregular: 2 pts
  • Extra-thyroidal extension: 3 pts

Category 5 — Echogenic Foci (∑Pfoci)

Echogenic foci reflect calcification patterns and psammomatous deposits. Because multiple foci types can coexist, their point values accumulate additively.

  • None or large comet-tail artifacts: 0 pts
  • Macrocalcifications (coarse foci with posterior acoustic shadowing): +1 pt
  • Peripheral (rim) calcifications (complete or incomplete marginal calcifications): +2 pts
  • Punctate echogenic foci without posterior shadow (psammoma body surrogates): +3 pts

TI-RADS Risk Categories and FNA Thresholds

Total scores translate directly into risk categories, each carrying size-based biopsy thresholds:

  • TR1 (0 pts) — Benign: No FNA or ultrasound follow-up required.
  • TR2 (2 pts) — Not Suspicious: No FNA or follow-up required.
  • TR3 (3 pts) — Mildly Suspicious: FNA if nodule measures ≥2.5 cm; follow-up if ≥1.5 cm.
  • TR4 (4–6 pts) — Moderately Suspicious: FNA if ≥1.5 cm; follow-up if ≥1.0 cm.
  • TR5 (≥7 pts) — Highly Suspicious: FNA if ≥1.0 cm; follow-up if ≥0.5 cm.

Worked Example

Consider a solid (2 pts), hypoechoic (2 pts), taller-than-wide (3 pts) nodule with irregular margins (2 pts), punctate echogenic foci (3 pts), and macrocalcifications (1 pt):

Score = 2 + 2 + 3 + 2 + 3 + 1 = 13 pts → TR5 (Highly Suspicious)

At 1.1 cm, this nodule exceeds the TR5 FNA threshold of ≥1.0 cm and warrants fine-needle aspiration. By contrast, a mixed cystic-solid (1 pt), isoechoic (1 pt), wider-than-tall (0 pts), smooth-margin (0 pts) nodule with no foci (0 pts) scores 2 pts → TR2 and requires no further workup regardless of size.

Comparison with Other Thyroid Ultrasound Systems

ACR TI-RADS is one of several thyroid ultrasound risk stratification systems alongside the American Thyroid Association (ATA) guidelines and Korean TI-RADS (K-TIRADS). ACR TI-RADS is distinguished by its granular 5-category additive point system and explicit separate scoring of each echogenic foci subtype. Clinicians transitioning from EU-TIRADS or ATA classifications should note that ACR TI-RADS assigns its highest echogenicity risk to nodules classified as very hypoechoic (3 pts), a finer distinction absent in some older frameworks.

Evidence Base and Validation

A comprehensive systematic review published in PubMed Central (PMC10607290) evaluated ACR TI-RADS across multiple cohorts and reported pooled sensitivity of approximately 78–87% and specificity of 57–74% for differentiating malignant from benign nodules. The system reduces unnecessary FNA by 37–54% compared to older size-only approaches. Structured reporting templates and integrated size-threshold guidance are available through Harvard MEEI’s TI-RADS Reporting Tool. Applied consistently, ACR TI-RADS reduces inter-observer variability and concentrates finite biopsy resources on nodules with the highest malignancy probability.

Reference

Frequently asked questions

What is the TI-RADS calculator and who should use it?
The TI-RADS calculator is a point-based risk stratification tool that assigns malignancy categories (TR1–TR5) to thyroid nodules based on five ultrasound features: composition, echogenicity, shape, margin, and echogenic foci. Radiologists, endocrinologists, and thyroid surgeons use it to standardize biopsy decisions, reduce unnecessary fine-needle aspiration procedures in low-risk nodules, and ensure consistent reporting across clinical sites.
What TI-RADS score indicates that a biopsy is needed?
Biopsy thresholds depend on both the TI-RADS category and nodule size. TR3 nodules (3 pts) warrant FNA at ≥2.5 cm. TR4 nodules (4–6 pts) require FNA at ≥1.5 cm. TR5 nodules (≥7 pts) need FNA at ≥1.0 cm. TR1 and TR2 nodules do not require FNA regardless of size, preventing unnecessary procedures in the majority of incidentally detected thyroid nodules seen on imaging.
How are punctate echogenic foci scored in TI-RADS?
Punctate echogenic foci — tiny bright spots without posterior acoustic shadowing — earn 3 points, the highest value within the echogenic foci category. They are considered surrogates for psammoma bodies, calcific deposits characteristically associated with papillary thyroid carcinoma. Because echogenic foci points are additive, a nodule displaying both punctate foci (3 pts) and peripheral rim calcifications (2 pts) accumulates 5 points from that single category alone.
What is the difference between TR4 and TR5 thyroid nodules?
TR4 nodules score 4–6 points and are classified as moderately suspicious, with estimated malignancy rates of roughly 5–20% depending on the study population. TR5 nodules score 7 or more points and are highly suspicious, with malignancy rates often exceeding 35%. The FNA size threshold also differs: 1.5 cm for TR4 versus 1.0 cm for TR5, reflecting the greater clinical urgency of histological evaluation in the higher-risk group.
How accurate is the ACR TI-RADS system for detecting thyroid cancer?
A systematic review published in PubMed Central (PMC10607290) reports ACR TI-RADS achieves pooled sensitivity of approximately 78–87% and specificity of 57–74% across multicenter cohorts. The system reduces unnecessary FNA procedures by 37–54% compared to size-only protocols. No single ultrasound feature provides diagnostic certainty; TI-RADS combines five independent predictors — including shape, echogenicity, and echogenic foci — to maximize both sensitivity and specificity simultaneously.
Can TI-RADS be used for nodules in patients with prior thyroid cancer or radiation exposure?
ACR guidelines recommend applying standard TI-RADS scoring even in high-risk patients — those with prior thyroid cancer history, childhood radiation exposure, or familial syndromes — but clinicians should consider lowering the FNA size threshold by one category in these populations. A TR3 nodule in a high-risk patient may warrant biopsy at 1.5 cm rather than 2.5 cm. The calculator provides the baseline risk score; individual clinical context should always inform the final management decision.