This is a free online calculator to estimate the risk of thyroid cancer (and the need for fine needle biopsy of thyroid nodules). It is based on the Thyroid Imaging Reporting and Data System (TI-RADS) endorsed by the American College of Radiology (ACR). The tool is intended for health care professionals only.
Enter relevant data on thyroid nodule composition, echogenicity, shape, margin and echogenic foci to generate the ACR-TIRADS level with associated recommendations.
Interpretation of results
TIRADS (TR) levels (total number of points):
- TR1 nodule is Benign (0 pts)
- TR2 nodule is Not Suspicious (2 pts)
- TR3 nodule is Mildly Suspicious (3 pts)
- TR4 nodule is Moderately Suspicious (4-6 pts)
- TR5 nodule is Highly Suspicious (≥7 pts)
TI-RADS Score Management Guidelines
ACR TI-RADS Score | Malignancy Risk | Plan |
0 | TR1 – Benign | FNAB is not indicated |
1 – 2 | TR2 – Not suspicious | FNAB is not indicated |
3 | TR3 – Mildly Suspicious | FNA if ≥ 2.5 cmFollow if ≥ 1.5 cm |
4 – 6 | TR4 – Moderately Suspicious | FNA if ≥ 1.5 cmFollow if ≥ 1 cm |
≥ 7 | TR5 – Highly Suspicious | FNA if ≥ 1 cm Follow if ≥ 0.5 cm |
FNAB : Fine Needle Aspiration Biopsy
Timing of Follow-Up Sonograms
The optimal timing for follow-up imaging of nodules that do not meet criteria for FNA is not standardized. Current guidelines recommend the following:
- TR5 lesions: Annual sonograms for up to 5 years.
- TR4 lesions: Imaging at 1, 2, 3, and 5 years.
- TR3 lesions: Follow-up at 1, 3, and 5 years.
If no size changes are observed during the 5-year period, imaging may be discontinued, reflecting benign behavior. For nodules that enlarge significantly but remain below FNA criteria, continued follow-up beyond 5 years may be required, though specific guidelines for such cases are lacking. If a nodule’s ACR TI-RADS (Thyroid Imaging Reporting and Data System) level increases, follow-up imaging should be scheduled within 1 year, regardless of its initial classification.
Number of Nodules to Biopsy
To minimize unnecessary procedures and patient discomfort, FNA biopsy should be limited to the two nodules with the highest suspicion based on imaging features. This approach balances the need for thorough evaluation with patient safety and comfort.
This comprehensive assessment framework ensures a systematic approach to evaluating thyroid nodules, prioritizing patient safety while optimizing diagnostic accuracy.
A Guide to Evaluating Thyroid nodules.
Composition
Thyroid nodules exhibit varying levels of risk based on their internal structure. Nodules that are cystic or predominantly cystic, including those classified as spongiform with multiple small cystic spaces, are generally considered benign. Conversely, nodules with solid components require careful evaluation, particularly when these components exhibit suspicious characteristics such as irregular margins, hypoechogenicity, or calcifications.
The recommended terminology for thyroid nodule composition is as follows:
- Cystic: Refers to nodules that are entirely fluid-filled.
- Predominantly cystic: Indicates nodules where the soft tissue component comprises less than 50% of the total volume.
- Predominantly solid: Refers to nodules where the soft tissue component accounts for more than 50% of the volume.
- Solid: Describes nodules that are almost entirely solid, with only a few tiny cystic spaces present.
- Spongiform: Composed of numerous small cystic spaces

Echogenicity
The echogenicity of a nodule is assessed by comparing its reflectivity to the adjacent thyroid tissue. For most nodules, this comparison provides an important clue to their nature.
Echogenicity is categorized into four levels, each compared to the surrounding tissue:
- Hyperechoic: Reflectivity is higher than that of the thyroid parenchyma.
- Isoechoic: Reflectivity is similar to the thyroid parenchyma.
- Hypoechoic: Reflectivity is lower than the thyroid parenchyma.
- Very hypoechoic: Reflectivity is lower than the neck musculature.
These distinctions provide a standardized framework for evaluating and describing nodule characteristics on ultrasound.

Shape
The shape of a nodule is a critical parameter in risk stratification. A nodule that is “taller-than-wide,” as measured in the axial plane (height exceeding width), is a highly specific indicator of malignancy. This characteristic often suggests aggressive growth patterns that warrant further diagnostic evaluation, including fine-needle aspiration (FNA) biopsy.

Margins
Nodule margins provide significant diagnostic insight. Smooth, well-defined margins are generally associated with benign lesions. In contrast, ill-defined or irregular margins, particularly those with protrusions, spicules, or lobulations, should raise suspicion for malignancy. Nodules that extend beyond the thyroid capsule or invade surrounding structures are especially concerning and suggest the possibility of invasive malignancy.
There are various margin descriptions
- Smooth: Found in spherical or elliptical nodules with well-defined, clear edges.
- Irregular: Characterized by spiculated, jagged, or sharp angles, often with protrusions extending into the surrounding parenchyma.
- Lobulated: Features rounded protrusions extending into the surrounding parenchyma.
- Ill-defined: Margins that cannot be clearly delineated, making it difficult to define the nodule’s boundary.
- Halo: A dark border surrounding the nodule, which may be complete or incomplete.
- Extrathyroidal extension: Occurs when the nodule has breached the thyroid capsule, extending into adjacent tissues.

Echogenic Foci
The presence and type of echogenic foci within a nodule influence its risk assessment. Punctate echogenic foci (microcalcifications) within solid components are particularly worrisome, as they are associated with papillary thyroid carcinoma. Larger coarse calcifications or peripheral eggshell calcifications may be seen in both benign and malignant nodules and should be interpreted in the context of other ultrasound features.
Various descriptions for echogenic foci
- Punctate echogenic foci: Small, “dot-like” structures measuring less than 1 mm in size.
- Macrocalcifications: Larger calcifications capable of producing a posterior acoustic shadow on ultrasound.
- Peripheral calcifications: Calcifications that encircle the majority of the nodule’s outer edge.
- Comet-tail artifacts: Reverberation artifacts appearing as triangular-shaped echoes.

Papillary Thyroid Microcarcinomas (PTMCs)
Routine biopsy is generally not recommended for nodules smaller than 1 cm, including PTMCs, unless specific clinical circumstances justify intervention. Exceptions may include cases where there is active surveillance, planned ablation, or consideration of surgical procedures such as lobectomy. Clinical judgment and patient-specific factors are essential in deciding management strategies for these small lesions.
Measurement and Documentation
Accurate measurement and thorough documentation of nodule size and location are essential for tracking changes over time. Measurements should include three dimensions (height, width, and depth) and should be recorded consistently to enable reliable comparison during follow-up assessments.
Definition of Growth
Growth is defined as a 20% or greater increase in at least two dimensions of the nodule, with a minimum size increase of 2 mm, or a 50% or greater increase in the nodule’s volume. Significant growth is an indicator for reevaluation and may necessitate a change in management strategy.

Limitations/Caveats
- A normal thyroid gland is brighter (hyperechoic) than the strap muscles (hypoechoic) on ultrasound. By comparing the brightness of the nodule to surrounding thyroid parenchyma, a thyroid nodule may be categorized as anechoic, hypoechoic, isoechoic, or hyperechoic.
- Anechoic, which correlates to 0 points on the ACR-TIRADS risk calculator, refers to a classic fluid-filled cyst. On the other hand, Very Hypoechoic is indicative of possible malignancy and refers to a nodule with an echogenicity lower than that of the overlying strap muscles.
- Classic pseudo-nodules seen in the setting of Hashimoto’s thyroiditis should not be classified as multiple hypoechoic and hyperechoic nodules. This background of multiple areas of variable echogenicity noted on thyroid ultrasound is sometimes referred to as Giraffe Skin Pattern. Furthermore, a uniform hyperechoic focus can be seen in a gland affected by Hashimoto’s thyroiditis. This is often described as a white knight nodule and is completely benign.
Reference(s)
Tessler FN, Middleton WD et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee. J Am Coll Radiol. 2017 May;14(5):587-595.