TIRADS Calculator & Report Generator

Evaluation of thyroid nodules on ultrasound using ACR's Thyroid Imaging Reporting & Data System (TI-RADS ™). The TIRADS calculator features images from ACR's atlas and is now equipped with a report generator!

TI-RADS (report)
1. How is the nodule's composition?
2. How is the nodule’s echogenicity? (Compared to the adjacent parenchyma)
3. How is the nodule's shape?
Note: Nodule's shape should be assessed on a transverse image with measurements parallel to the sound beam for height and perpendicular to the sound beam for width.
4. How are the margins?
5. Are there any additional features? Choose all that apply.
Large comet-tail artifacts = V-shaped, >1mm, in cystic components
Macrocalcifications = cause acoustic shadowing
Peripheral/rim calcifications = along margin, either complete or partial
Punctate echogenic foci = may have small comet-tail artifacts

TI-RADS Score:

→ No further follow-up is needed.
→ No further follow-up is needed.
Note: Spongiform, cystic, and almost completely cystic nodules always have a TI-RADS score of 1, irrespective of their other features.
→ No further follow-up is needed.
→ FNA if ≥ 2.5cm
→ Follow-up imaging if ≥ 1.5cm (in 1, 3, and 5 years)
→ FNA if ≥ 1.5cm
→ Follow-up imaging if ≥ 1cm (in 1, 2, 3, and 5 years)
→ FNA if ≥ 1cm
→ Follow-up imaging if ≥ 0.5cm (annually up to five years)
Answer all questions to calculate the final score
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More about the ACR TI-RADS Calculator

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This calculator is designed to assist radiologists and trainees in assessing thyroid nodule risk using the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS). This thyroid ultrasound scoring system provides a structured framework for evaluating nodules and estimating malignancy risk, making it a valuable tool for clinical decision-making. By combining sonographic features into a cumulative score, the calculator supports evidence-based recommendations for biopsy or surveillance and streamlines thyroid nodule risk assessment in everyday practice.

The clinical management of thyroid nodules has evolved significantly with the widespread adoption of the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS). Designed to address the high prevalence of incidental thyroid nodules detected in up to 68% of high-resolution ultrasound examinations and the associated potential for overdiagnosis, the TI-RADS calculator provides a standardized, quantitative framework for malignancy risk stratification.

Unlike European (EU-TIRADS) or Korean (K-TIRADS) systems which rely on pattern recognition, this thyroid ultrasound scoring tool utilizes a point-based methodology. This approach weights individual sonographic features based on their positive predictive value (PPV) for malignancy. By prioritizing high specificity, the thyroid nodule risk calculator aims to significantly reduce the volume of unnecessary fine-needle aspiration (FNA) biopsies of benign or indolent lesions while maintaining sensitivity for clinically significant disease.

This reference guide details the scoring mechanics, clinical interpretation, reporting nuances, and limitations essential for board-certified radiologists and trainees utilizing the TI-RADS calculator.

The Five Ultrasound Feature Categories

The TI-RADS risk assessment derives a cumulative score from five sonographic categories. Points are assigned based on the feature most suspicious for malignancy within each category. This weighted system ensures that high-risk features contribute disproportionately to the total score generated by the thyroid ultrasound scoring tool, accurately reflecting the increased probability of malignancy.

1. Composition
This category assesses the internal architecture of the nodule.

  • Cystic or almost completely cystic (0 points): These lesions are benign and require no further scoring.
  • Spongiform (0 points): Defined as composed of greater than 50% small cystic spaces, this appearance is highly specific for benignity.
  • Mixed cystic and solid (1 point): This applies regardless of the proportion of the solid component, provided it does not meet spongiform criteria.
  • Solid or almost completely solid (2 points): This feature carries a higher risk association. For scoring purposes, visual estimation of >95% solid is sufficient.

2. Echogenicity
Echogenicity is evaluated relative to the surrounding thyroid parenchyma and the anterior neck musculature. For mixed nodules, the score is based exclusively on the solid component.

  • Anechoic (0 points): Applies to cystic fluid.
  • Hyperechoic or Isoechoic (1 point): Increased or similar echogenicity relative to the thyroid parenchyma.
  • Hypoechoic (2 points): Less echogenic than thyroid parenchyma.
  • Very Hypoechoic (3 points): Less echogenic than the adjacent strap muscles. This is a specific indicator of malignancy and carries significant weight in the TI-RADS calculator.

3. Shape
Shape is assessed exclusively in the transverse (axial) plane.

  • Wider-than-tall (0 points): The anteroposterior diameter is less than or equal to the transverse diameter (parallel orientation).
  • Taller-than-wide (3 points): The anteroposterior diameter exceeds the transverse diameter (non-parallel orientation). This feature reflects centrifugal growth against tissue planes and is a strong independent predictor of malignancy.

4. Margin
This category evaluates the interface between the nodule and the surrounding tissue.

  • Smooth (0 points): Uninterrupted, well-defined border.
  • Ill-defined (0 points): The border merges imperceptibly with the thyroid parenchyma. It is critical to distinguish this from an infiltrative margin; ill-defined margins in isolation are generally benign.
  • Lobulated or Irregular (2 points): Spiculated or jagged edges, or protrusions into the parenchyma.
  • Extrathyroidal Extension (3 points): Frank invasion into adjacent soft tissue or vascular structures. Mere bulging of the capsule does not qualify as extension.

5. Echogenic Foci
Unlike other categories where a single feature is selected, multiple features can be selected in this category, and their points are additive.

  • None or Large Comet-tail Artifacts (0 points): V-shaped artifacts >1 mm in depth are typically associated with colloid and benignity.
  • Macrocalcifications (1 point): Coarse calcifications with posterior acoustic shadowing.
  • Peripheral (Rim) Calcifications (2 points): Calcification along the nodule margin. These should be scrutinized carefully, as complete shadowing may obscure central malignant components.
  • Punctate Echogenic Foci (3 points): These correspond to psammomatous calcifications associated with papillary thyroid carcinoma. They are smaller than macrocalcifications and lack the deep V-shaped tail of colloid artifacts.

Clinical Interpretation: TR Categories and Management with the TI-RADS Calculator

The sum of points determines the TI-RADS (TR) level. This TI-RADS risk assessment score correlates with malignancy risk and dictates size-based management thresholds.

A defining characteristic of the ACR TI-RADS is the intentional use of higher size thresholds for biopsy compared to other international guidelines. This shift is largely driven by the reclassification of Noninvasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP). Recognizing NIFTP as an indolent lesion, the ACR established these thresholds to minimize the overtreatment of non-threatening neoplasms, prioritizing clinical significance over mere detection.

Table: ACR TI-RADS TR categories and management recommendations using the TI-RADS calculator
CategoryPointsMalignancy RiskManagement
TR1: Benign0< 0.3%No FNA required.
TR2: Not Suspicious2~1.5%No FNA required.
TR3: Mildly Suspicious3~4.8%FNA if ≥ 2.5 cm
Follow-up US if ≥ 1.5 cm
TR4: Moderately Suspicious4-6~9.1%FNA if ≥ 1.5 cm
Follow-up US if ≥ 1.0 cm
TR5: Highly Suspicious≥ 7~35%FNA if ≥ 1.0 cm
Follow-up US if ≥ 0.5 cm

Global Context: Comparison with EU-TIRADS and K-TIRADS

While all major risk stratification systems aim to identify thyroid malignancy, they differ fundamentally in their approach and clinical goals.

  • Methodology: The TI-RADS calculator employs a point-based system, where specific features are weighted and summed. In contrast, EU-TIRADS (European) and K-TIRADS (Korean) utilize pattern-based systems, where nodules are matched to visual templates or patterns.
  • Sensitivity vs. Specificity: The ACR system is optimized for specificity. By setting higher biopsy size thresholds and requiring substantial sonographic evidence to escalate risk, the thyroid nodule risk calculator results in the highest percentage of avoided biopsies among the major guidelines. Conversely, K-TIRADS and EU-TIRADS generally prioritize sensitivity, leading to higher detection rates but a concomitant increase in biopsies of benign nodules.
  • The "Blind Spot": Radiologists should be aware that the high specificity of the TI-RADS risk assessment creates a potential "blind spot" for small (1.0-1.5 cm), solid, hyperechoic nodules. These are classified as TR3 and would not undergo biopsy until reaching 2.5 cm under ACR guidelines, whereas other systems might recommend earlier intervention.

Limitations and Pitfalls

Interobserver Variability
While the thyroid ultrasound scoring tool provides a structured lexicon, the subjective nature of ultrasound interpretation introduces variability. While agreement on final biopsy recommendations is generally substantial, concordance for specific features varies:

  • Margins: This remains a primary source of discordance. Differentiating between "ill-defined" (0 points) and "lobulated/irregular" (2 points) can be challenging. The lack of strict quantitative criteria for what constitutes a "lobulation" necessitates careful judgment.
  • Shape: While "taller-than-wide" is a specific marker, assessing round nodules (where the ratio approaches 1:1) can lead to variability in scoring. Consistent measurement in the transverse plane is required to mitigate this.

Pathology Correlation: PTC vs. FTC
The diagnostic performance of the TI-RADS calculator is strongest for the classical variant of papillary thyroid cancer (PTC), which typically displays high-risk features like microcalcifications and hypoechogenicity. Sensitivity decreases for follicular thyroid carcinoma (FTC) and the follicular variant of PTC. These subtypes frequently present as encapsulated, isoechoic, or hyperechoic nodules which result in lower TR scores (TR3 or TR4), potentially leading to surveillance rather than immediate biopsy despite malignancy.

Special Clinical Scenarios

  • Multinodular Goiter: In patients with multinodular goiter, assessing every nodule is impractical. To maintain efficiency, the ACR recommends reporting the four most suspicious nodules, not necessarily the largest. FNA should be limited to a maximum of two nodules with the highest TR scores that meet size criteria.
  • Previously Treated Nodules: The thyroid nodule risk calculator is validated for untreated nodules. Prior FNA, thermal ablation, or ethanol ablation can induce hemorrhage, scarring, and architectural distortion. These changes often mimic malignant features (e.g., hypoechogenicity, irregular margins), rendering standard TI-RADS scoring unreliable.

Follow-Up Intervals and Surveillance

For nodules that do not meet the size threshold for biopsy, the ACR TI-RADS committee suggests specific surveillance intervals. These are practice patterns rather than rigid mandates, designed to detect interval growth or morphologic changes.

  • TR5: Annual follow-up for up to 5 years.
  • TR4: Follow-up at 1, 2, 3, and 5 years.
  • TR3: Follow-up at 1, 3, and 5 years.

Cessation of Surveillance: If a nodule demonstrates stability in size and appearance over a 5-year surveillance period, its biological behavior is generally considered benign, and further follow-up may be discontinued.

Frequently Asked Questions

  • How strictly should size thresholds for FNA be applied?
    The size thresholds (1.5 cm for TR4 and 1.0 cm for TR5) balance cancer detection with the prevention of overdiagnosis. While strict adherence maintains the system’s high specificity, clinical judgment is paramount. Factors such as patient anxiety, comorbidities, or proximity to critical structures (e.g., trachea, recurrent laryngeal nerve) may justify deviation from the standard TI-RADS risk assessment protocols.
  • How should partially cystic nodules be scored?
    Partially cystic nodules are assigned 1 point for composition ("mixed cystic and solid"). However, points for echogenicity, margins, and echogenic foci should be based exclusively on the appearance of the solid component or the nodule periphery.
  • Do punctate echogenic foci always represent microcalcifications?
    Not always. While punctate foci often represent psammomatous calcifications (highly associated with PTC), they can occasionally represent inspissated colloid. The key discriminator is the absence of a large comet-tail artifact. If uncertain, it is safer to score them as punctate foci (3 points) to ensure appropriate risk stratification.
  • How is taller-than-wide shape defined in practice?
    This feature is defined strictly as the anteroposterior diameter exceeding the transverse diameter when measured in the axial (transverse) plane. Measurements taken in the longitudinal/sagittal plane are not used for this determination in the TI-RADS calculator.
  • Why does ACR TI-RADS use a point-based system instead of patterns?
    The point-based system provides a more objective thyroid ultrasound scoring tool that prioritizes specificity. By assigning weights to features based on their statistical correlation with malignancy, the system reduces the subjectivity inherent in "best-fit" pattern recognition models.
  • When is surveillance preferred over biopsy?
    Surveillance is preferred for nodules that meet the TR level criteria but fall below the size threshold for biopsy (e.g., a 0.8 cm TR5 nodule). Additionally, active surveillance is increasingly accepted for small (<1.0 cm), low-risk papillary thyroid microcarcinomas (PTMC) without nodal metastasis or extrathyroidal extension.
  • How should interval growth be interpreted?
    Significant interval growth is defined as a 20% increase in at least two dimensions with a minimum increase of 2 mm, or a 50% increase in volume. If a nodule grows but remains below the FNA threshold for its TR category, the next follow-up is typically scheduled after 1 year.
  • Can TI-RADS be applied to incidental thyroid nodules?
    Yes. ACR TI-RADS was specifically designed to manage the increasing volume of incidental thyroid nodules ("incidentalomas") detected on CT, MRI, or PET scans. Once identified, these nodules should be evaluated with dedicated thyroid ultrasound and scored according to TI-RADS risk assessment criteria.
  • What is the impact of NIFTP on the guidelines?
    The recognition of NIFTP (Noninvasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features) as an indolent lesion significantly influenced the ACR guidelines. The higher biopsy thresholds in the thyroid nodule risk calculator aim to avoid over-treating these non-aggressive neoplasms, which previously might have been classified as carcinomas requiring surgery.
Dr. Pooyan Khalighinejad
Reviewed by Pooyan Khalighinejad M.D.
PGY-5 Radiology Resident Physician, UT Southwestern Medical Center, USA

3 Comments

  1. Avatar of Orla Orla says:

    Hi there,

    I just used the TI-RADS calculator for a nodule with the following charactristics:
    Nodule #1:
    – Location: left lobe (mid segment)
    – Size: 0.7 cm
    – Composition: Solid or almost completely solid
    – Echogenicity: Hypoechoic
    – Shape: Wider than tall
    – Margins: Smooth
    – Additional findings: Peripheral/rim calcifications

    And it has classed the nodule as TR 4 rather than 5.

    Really appreciate the tool 🙂

    • Avatar of Pooyan Khalighinejad M.D. Pooyan Khalighinejad M.D. says:

      Hello Orla,
      Thanks for your feedback. Based on the characteristics you listed: solid (2), hypoechoic (2), peripheral/rim calcifications (2), smooth margins (0), wider than tall (0), the total comes to 6 points, which corresponds to TR-4. Could you clarify which feature you counted that led to TR-5?

  2. Avatar of Josh P Josh P says:

    What an incredibly helpful tool! Thank you!

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