Learn ACR TI-RADS scoring step by step using composition, echogenicity, shape, margin, and echogenic foci, with a report example and common pitfalls.
ACR TI-RADS is a scoring system used to describe thyroid nodules consistently according to their ultrasound features, categorize the level of suspicion for malignancy, and apply size-based biopsy and follow-up thresholds in a standardized manner. It adds the points assigned under five imaging headings: composition, echogenicity, shape, margin, and echogenic foci.
This article is intended for education. Patient management should be based on the current ACR document, the clinical context, prior examinations, and institutional protocols.
Thyroid nodules are extremely common, and most are benign. When a report includes only a single feature such as “hypoechoic nodule,” the referring clinician may have difficulty understanding the nodule's overall risk profile and the recommended next step. ACR TI-RADS aims to help different readers describe the same nodule using more consistent language.
The system separates three tasks:
The category is not a pathologic diagnosis. “TR5” does not confirm malignancy; it indicates that the imaging features are highly suspicious.
First, make sure that the finding is a discrete nodule. Pseudonodular areas in thyroiditis, heterogeneous parenchyma alone, and non-mass-like foci may lead to unnecessary scoring. Measure the nodule in three orthogonal dimensions and record the largest diameter. When prior imaging is available, compare measurements in the same plane and with similar caliper placement.
Composition describes the relative proportion of cystic and solid components. The general ACR scoring approach is:
A few small cystic spaces do not make a nodule spongiform. The predominant portion of the nodule should contain numerous small cystic spaces. In a mixed nodule, assess echogenicity using the solid component.
Echogenicity is compared with the surrounding thyroid parenchyma and, when needed, the strap muscles:
A “very hypoechoic” nodule is expected to be less echogenic than the strap muscles. Gain settings and diffuse parenchymal hypoechogenicity in thyroiditis may affect this assessment.
This feature is assessed in the transverse plane using measurements parallel and perpendicular to the ultrasound beam. Slightly oblique caliper placement may incorrectly produce a taller-than-wide result.
An ill-defined margin is not the same as an irregular margin. With an ill-defined margin, the transition between the nodule and thyroid parenchyma cannot be clearly identified. An irregular margin shows angulation, notching, or spiculated extensions. Extrathyroidal extension is not simply contact with the capsule; there should be convincing evidence of invasion into adjacent tissues.
More than one applicable feature may be scored under this heading:
Distinguish colloid foci that may produce a small comet-tail artifact from true punctate echogenic foci. Automatically labeling every bright focus within a nodule as “microcalcification” increases false-positive scoring.
| Total points | ACR TI-RADS category | Brief meaning |
|---|---|---|
| 0 | TR1 | Benign |
| 2 | TR2 | Not suspicious |
| 3 | TR3 | Mildly suspicious |
| 4–6 | TR4 | Moderately suspicious |
| 7 or more | TR5 | Highly suspicious |
In the assessment chart published by the ACR, the biopsy thresholds are summarized as 2.5 cm for TR3, 1.5 cm for TR4, and 1.0 cm for TR5. Ultrasound follow-up thresholds are lower: 1.5 cm for TR3, 1.0 cm for TR4, and 0.5 cm for TR5. Routine FNA is not recommended for TR1 or TR2 nodules. These thresholds are not substitutes for clinical judgment; age, symptoms, risk history, lymph nodes, prior cytology, and the overall clinical context must also be considered.
Findings: A 16 × 12 × 11 mm nodule in the mid right lobe that is solid, hypoechoic, wider-than-tall, smoothly marginated, and contains no punctate echogenic foci.
Because the largest diameter is 1.6 cm, FNA may be considered in accordance with official thresholds and the clinical context.
In the mid right thyroid lobe, there is a 16 × 12 × 11 mm solid hypoechoic nodule that is wider-than-tall in the transverse plane, has smooth margins, and contains no suspicious echogenic foci. The ACR TI-RADS score is 4, corresponding to category TR4. Given the size criterion, ultrasound-guided fine-needle aspiration may be considered.
Writing only “TR4” in the report is not sufficient. Explicitly documenting the features allows the score to be audited and makes it easier to understand which component has changed on follow-up.
Including every nodule in detail may reduce report readability. The ACR approach prioritizes nodules with the highest score and those that generate a management recommendation. The largest nodule is not always the most suspicious. Numbering nodules that require biopsy or follow-up and recording laterality and segment location helps streamline the workflow.
Assess echogenicity using the solid component.
Poor definition alone is not irregularity.
Distinguish colloid artifact, macrocalcification, and true punctate foci.
Two nodules in the same TR category may receive different recommendations if their sizes differ.
ACR TI-RADS does not independently define the entire management pathway for nodules with prior cytology. Cytology, clinical guidelines, and previous results should be considered together.
Before signing the report, ask these five questions:
No. TR4 indicates that the ultrasound features are moderately suspicious. It is not a definitive diagnosis.
The category is primarily based on morphology. Size change may affect the follow-up decision, but the category should not be reduced automatically without reassessing the morphology.
No. Suspicious cervical lymph nodes are assessed separately and may substantially affect patient management.
This content is educational and is not patient-specific medical advice. Every phrase, template, classification result, and recommendation must be verified and adapted by a physician using the complete examination, clinical context, current guidelines, and institutional protocol.
Use the relevant RadPhrases calculator, then verify the result against the official guideline and the complete examination.
Apply the classification or measurement steps from this guide in an interactive tool.
