Best Practices for Measuring Thyroid Nodules
Accurate and reproducible measurement of thyroid nodules on ultrasound is crucial for follow-up, management decisions, and comparisons over time. Here are key best-practice considerations:
1. Caliper Placement & Dimensional Technique
Use three-dimensional (3D) measurement for nodules > 1 cm, capturing the anteroposterior (height), transverse (width) and longitudinal (length) diameters. PMC
On transverse images, measure the maximum width (W) and the height (H) perpendicular to width. On longitudinal (sagittal) images, measure the maximum length (L). PMC+1
Place calipers at the outer margin of the halo or the nodule boundary consistently. One inter-observer variation study defined this method to improve reliability. PMC
Once W, H & L are defined, maximum diameter is the greatest of the three. Volume can be estimated by the ellipsoid formula: length × width × height × π/6. PMC
2. Technical Factors & Standardization
Use a high-frequency linear transducer optimized for superficial structures (thyroid) for best resolution.
Ensure standardized patient position (neck slightly extended), minimal transducer pressure (to avoid compressing the nodule and altering dimensions), and consistent scan planes across follow-ups.
Document the exact location of the nodule (e.g., lobe, level: upper/mid/lower, anterior/posterior) so repeat measurements target the same area. PMC+1
Record not only size but also ultrasound features (echogenicity, margins, calcifications, vascularity) as per standardized reporting to support decision-making. PMC+1
3. Reproducibility & Follow-up Criteria
Inter-observer variation is real: a study showed that when measurement methods were standardized, the variation in nodule volume measurement was about 6.6%, but previous studies found variation up to 48.6%. PMC
For follow-up, guidelines define significant growth as an increase of ≥ 20% in at least two diameters with minimum increase of 2 mm, or a volume increase of > 50%. PMC
Use consistent measurement methods (same scanner settings if possible, same dimension definitions) for serial comparisons. Variability in technique can mimic growth or shrinkage erroneously.
4. Practical Tips for Sonographers & Clinicians
Always label each dimension (AP, transverse, longitudinal) clearly on the image and in report.
Save representative images for each dimension to enable comparison on future exams.
In mixed cystic-solid nodules or irregular margins, note when measurement boundaries are less distinct – variability may be higher. Consider qualitative comment and larger safety margins for “growth”.
When multiple nodules are present, identify and measure the same target nodule each time; note the nodule’s unique location and characteristics to avoid confusion.
Communicate measurement method in the report (e.g., calipers placed at outer margin, 3-D measurement used) so reviewers understand the baseline method.
Summary
Precise, standardized measurement of thyroid nodules — consistent caliper placement, documented dimensions, and stable technical parameters — is essential for monitoring changes over time with confidence. By applying the best practices above, you enhance reproducibility and ensure that size changes reflect true growth (or shrinkage), not measurement error.
How the ACR TI-RADS™ (“TI-RAD”) System Was Created and Researched
Introduction
The term TI-RAD, more formally known as the Thyroid Imaging Reporting & Data System (TI‑RADS), refers to a set of ultrasound-based risk stratification frameworks for assessing thyroid nodules. Its key purposes include: standardizing ultrasound/sonographic descriptions of nodules, stratifying malignancy risk, and guiding decisions on fine-needle aspiration (FNA) and follow-up. (American College of Radiology)
Particularly, the version from the American College of Radiology (ACR) was introduced in 2017. (Radiology Assistant)
In this post we'll explore how TI-RAD was developed, the research behind it, and how “TI RAD calculator” tools have arisen to operationalize it.
Origins & Rationale
Prior to TI-RAD, thyroid nodules were extremely common (some studies mention up to 50-60% prevalence on ultrasound in certain populations) and the challenge was distinguishing benign from malignant while avoiding unnecessary biopsies. (Radiology Assistant)
The ACR states three primary goals for developing their TI-RAD system:
Develop management guidelines for incidentally found thyroid nodules on imaging. (American College of Radiology)
Produce a lexicon of ultrasound features (e.g., composition, echogenicity, margin, shape, echogenic foci) that radiologists could use consistently. (American College of Radiology)
Create a standardized point‐based risk-stratification system based on that lexicon to guide decisions on biopsy vs follow-up. (American College of Radiology)
By applying a consistent scoring framework, the idea was to reduce variability in reporting between radiologists and reduce unnecessary procedures for benign nodules. (gehealthcare.ca)
Development of ACR TI-RAD (2017)
The formal ACR TI-RAD white paper (Tessler et al., 2017) describes how the system was derived from a database of over 3,000 thyroid nodules with known pathology. (JACR)
Key components:
Each ultrasound feature (composition; echogenicity; shape; margin; echogenic foci) is assigned a numeric point value. (Radiology Assistant)
The sum of points determines the TI-RAD category: TR1 (benign) through TR5 (highly suspicious). (Radiology Assistant)
Size thresholds for recommending FNA or follow-up are built into the recommendations (e.g., TR3 nodules only get FNA if ≥ 2.5 cm). (Radiology Assistant)
For example, RadiologyAssistant summarizes that the risk of malignancy by category is approximately:
TR1 ~ 0.3%
TR2 ~ 1.5%
TR3 ~ 4.8%
TR4 ~ 9.1%
TR5 ~ 35% (Radiology Assistant)
Research, Validation & Performance
Since its introduction, many studies have validated and compared ACR TI-RAD with other systems. Highlights include:
A study comparing four different TI-RAD algorithms found ACR TI-RAD had higher specificity and helped reduce unnecessary FNAs. (PMC)
Another validation study (Merhav et al., 2021) compared ACR TI-RAD vs the American Thyroid Association (ATA) Guidelines in 281 nodules and noted that TI-RAD more often avoided FNA in nodules that were benign. (Journal of Clinical Imaging Science)
An update paper (Hoang et al., 2021) reviewed successes, challenges and future directions of ACR TI-RAD — for example addressing over-diagnosis and refining size thresholds. (AJR Online)
In operational practice, use of TI-RAD has been shown to improve inter-reader consistency of reporting and guide management decisions more transparently. (gehealthcare.ca)
TI RAD Calculator Tools
With the system defined, several “TI RAD calculator” tools have emerged to help clinicians apply the scoring/risk stratification quickly:
A free online tool “TI-RAD Calculator” at tiradscalculator.com lets users input ultrasound features and get a TR category. (tiradscalculator.com)
Another calculator by Dr. Phillip Cheng provides a web-based scoring interface. (pcheng.org)
Additional calculators integrate reporting templates and images (e.g., RadAtHand’s TI-RAD calculator + report generator). (Rad at Hand)
These calculators help operationalize the keyword “TI RAD calculator” and support consistent application of the TI-RAD system across ultrasound practices.
Why It Matters
For thyroid nodules (keyword: “Thyroid TI-RAD Nodules”), TI-RAD brings major advantages:
Standardization: Using defined ultrasound descriptors reduces variability in how nodules are described and managed.
Risk stratification: It provides clear categories with associated malignancy risks and follow-up/biopsy recommendations, based on evidence.
Efficiency: By applying size and feature thresholds, TI-RAD helps avoid unnecessary FNAs in benign nodules, reducing patient burden and cost.
Decision-support: The calculators make it easier for ultrasound techs, radiologists and endocrinologists to apply the system in real time.
Limitations & Future Directions
No system is perfect. The TI-RAD framework has some caveats:
It is validated mainly for adult thyroid nodules; it may not apply in pediatric populations or in certain high-risk contexts (e.g., FDG-PET-avid nodules, known genetic risk). (Radiology Assistant)
Studies note that while specificity is improved, sensitivity can still be improved – some malignant nodules may be under-scored. (AJR Online)
“TI RAD” calculators must be used as adjuncts — not replacing clinical judgment, patient context, and multidisciplinary discussions.
Future work is looking at integrating advanced imaging features (e.g., elastography, artificial-intelligence segmentation) into TI-RAD-based decision systems. (BioMed Central)
Summary
The TI-RAD system—most commonly referring to ACR TI-RAD—represents a major advance in thyroid ultrasound interpretation. Created to standardize reporting, stratify risk of malignancy in thyroid nodules, and reduce unnecessary biopsies, it still forms the backbone of many clinical workflows today. The addition of “TI RAD calculator” tools helps make the scoring efficient and reproducible. As research advances, TI-RAD continues to adapt, incorporating new imaging markers and decision-support technologies.
🩺 TI-RADS Ultrasound Examples: Understanding Each Scoring Characteristic
Keywords: TI-RADS examples, thyroid ultrasound features, TI-RADS composition echogenicity shape margin foci, ACR TI-RADS scoring, thyroid nodule ultrasound examples
Introduction
When learning the ACR TI-RADS system, visual examples are key to understanding how each ultrasound feature contributes to the overall score.
Below are descriptions and image placeholders for each of the five TI-RADS characteristics with notes on how they affect scoring.
You can view the full scoring reference on the ACR TI-RADS Guidelines (Radiopaedia).
1️⃣ Composition
TI-RADS assigns 0–2 points based on how solid or cystic a nodule is.
TypeDescriptionPoints
Cystic or almost completely cysticAnechoic, fluid-filled, thin walls. Usually benign colloid cyst.0
Spongiform>50% small cystic spaces; classic benign pattern.0
Mixed cystic and solidBoth fluid and soft-tissue components visible.1
Solid or almost completely solidHypoechoic, dense tissue with minimal cystic change.2
2️⃣ Echogenicity
Echogenicity measures how bright or dark the nodule is compared to normal thyroid tissue.
TypeAppearancePoints
AnechoicCompletely black (fluid-filled) — cystic lesions.0
Isoechoic or Hyperechoic Same or brighter than thyroid parenchyma.1
HypoechoicDarker than thyroid tissue, brighter than strap muscles.2
Very HypoechoicEqual to or darker than adjacent strap muscles — more suspicious.3
3️⃣ Shape
Shape is one of the most critical indicators of malignancy.
ShapeAppearancePoints
Wider-than-tallThe nodule’s width (transverse) is greater than its height (AP). Usually benign.0
Taller-than-wideHeight exceeds width on transverse view — suggests invasive growth.3
4️⃣ Margins
Margins show how well-defined or irregular the edges of the nodule are.
Margin Type
Smooth Clear, even contour. Benign.0
Ill-defined Fuzzy edges; can occur in benign or malignant nodules.0
Lobulated or Irregular Jagged, uneven outline suggesting infiltration.2
Extrathyroidal Extension Nodule breaks capsule or extends into surrounding tissue.3
5️⃣ Echogenic Foci
These small internal echoes help identify calcifications or colloid artifacts.
Foci Type
None or Large Comet-Tail Artifact Benign colloid reflection.0
Macrocalcifications Large bright echoes with posterior shadowing.1
Peripheral / Rim Calcifications Calcified rim around the nodule.2
Punctate Echogenic FociTiny bright dots (microcalcifications) — more suspicious.3
Putting It All Together
Each characteristic contributes to a total TI-RADS score:
0 points → TR1 (benign)
2 points → TR2 (not suspicious)
3 points → TR3 (mildly suspicious)
4–6 points → TR4 (moderately suspicious)
≥7 points → TR5 (highly suspicious)
Once you’ve assessed your nodule, enter these findings into the TI-RADS Calculator to instantly view your total score, malignancy risk, and recommended follow-up interval.
How the TI-RADS System Works: Understanding Thyroid Nodule Scoring
Keywords: how TI-RADS works, ACR TI-RADS explained, TI-RADS thyroid ultrasound, TI-RADS scoring system, thyroid nodule risk classification, ACR TI-RADS calculator
What Is TI-RADS?
The Thyroid Imaging Reporting and Data System (TI-RADS) is a standardized method developed by the American College of Radiology (ACR) to classify thyroid nodules found on ultrasound.
Its goal is simple: make thyroid nodule reporting consistent, evidence-based, and easy to interpret across sonographers, radiologists, and referring clinicians.
Instead of vague terms like “slightly suspicious” or “needs follow-up,” TI-RADS assigns points to specific ultrasound features. These points add up to a category (TR1–TR5) that reflects the likelihood of malignancy and helps determine whether fine-needle aspiration (FNA) or follow-up imaging is recommended.
If you’d like to review the official source, you can read the
👉 ACR TI-RADS guidelines on Radiopaedia
for full scoring tables and management recommendations.
The Five Key Features of TI-RADS
The ACR system evaluates five ultrasound features, each worth a certain number of points:
Composition: Cystic (0), Spongiform (0), Mixed (1), Solid (2)
Echogenicity: Anechoic (0), Hyperechoic/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), Extrathyroidal extension (3)
Echogenic Foci: None (0), Large comet tail (0), Macrocalcifications (1), Peripheral/rim calcifications (2), Punctate echogenic foci (3)
Each selected option contributes to the total score.
TI-RADS Categories and What They Mean
TR1 – Benign (0 points)
Likelihood of malignancy: ~0%
Recommendation: No FNA or follow-up.
TR2 – Not Suspicious (2 points)
Likelihood of malignancy: ~1.5%
Recommendation: No FNA or follow-up.
TR3 – Mildly Suspicious (3 points)
Likelihood of malignancy: ~4.8%
Recommendation: Follow-up ≥1.5 cm; FNA ≥2.5 cm.
TR4 – Moderately Suspicious (4–6 points)
Likelihood of malignancy: ~9.1%
Recommendation: Follow-up ≥1.0 cm; FNA ≥1.5 cm.
TR5 – Highly Suspicious (≥7 points)
Likelihood of malignancy: ~35%
Recommendation: Follow-up ≥0.5 cm; FNA ≥1.0 cm.
These thresholds are based on the ACR TI-RADS guidelines and can help reduce unnecessary biopsies while ensuring significant nodules are properly investigated.
Why TI-RADS Is Important
Before TI-RADS, thyroid ultrasound reports varied dramatically between practitioners.
Now, using TI-RADS:
Sonographers and radiologists speak a common language.
Patients receive clear, evidence-based follow-up recommendations.
Clinics minimize over-biopsy and streamline workflows.
This consistency improves communication with referring physicians and ultimately leads to better patient outcomes.
How to Apply It in Practice
When performing a thyroid ultrasound:
Identify and document each nodule’s five core features.
Use the TI-RADS Calculator to assign points and automatically determine the category.
Include the category (e.g., TR4) and recommended action in your report.
For follow-up, note the time interval (e.g., TR3 nodules > 1.5 cm → repeat at 1, 3, and 5 years).
Over time, applying TI-RADS consistently will sharpen your diagnostic accuracy and help you build stronger clinical confidence.
Want to Calculate a Score Instantly?
👉 Try the ACR TI-RADS Calculator — a free, easy-to-use tool built by a fellow sonographer to simplify your thyroid reporting workflow.
How to use the TI-Rads online calculator
It all begins with an idea.
🧠 How to Use the ACR TI-RADS Online Calculator — and Why It Matters
Keywords: TI-RADS calculator, ACR TI-RADS online calculator, thyroid nodule risk calculator, TI-RADS ultrasound scoring, how to calculate TI-RADS, thyroid ultrasound interpretation
What Is the TI-RADS Calculator?
The TI-RADS (Thyroid Imaging Reporting and Data System) is a standardized scoring system developed by the American College of Radiology (ACR) to help sonographers and radiologists assess thyroid nodules consistently. Each ultrasound feature—such as composition, echogenicity, shape, margin, and echogenic foci—earns points that combine into an overall TI-RADS score. This score helps estimate the risk of malignancy and guides decisions on biopsy or follow-up.
Our ACR TI-RADS Calculator at SonoCalcLab.com lets you enter these features quickly and automatically see:
The total TI-RADS points
The corresponding TI-RADS category (TR1–TR5)
The estimated likelihood of malignancy
The recommended follow-up interval or FNA (fine-needle aspiration) threshold
No math, no guesswork—just clear results instantly.
How to Use the TI-RADS Calculator
Select each ultrasound feature
Choose the composition (solid, mixed cystic, etc.)
Select echogenicity, shape, margin, and echogenic foci
Each choice automatically adds points according to the ACR guidelines
View your TI-RADS score
The calculator instantly totals your score and displays the category (TR1–TR5).Interpret the results
TR1–TR2: Benign or not suspicious
TR3: Mildly suspicious (follow-up if ≥1.5 cm)
TR4: Moderately suspicious (consider FNA if ≥1.5 cm)
TR5: Highly suspicious (FNA if ≥1 cm)
Follow recommended management
The calculator also displays the recommended ultrasound follow-up intervals (e.g., 1, 3 and 5 years for TR3 nodules > 1.5 cm).
You can use this tool directly in your reporting workflow or as a double-check while documenting thyroid findings.
Why TI-RADS Scoring Matters
Before the ACR introduced TI-RADS, thyroid ultrasound interpretation varied widely between practitioners. By adopting this system:
Radiologists and sonographers speak the same language when describing nodules.
Patients receive consistent, evidence-based care.
Clinics reduce unnecessary biopsies and focus on nodules that truly need follow-up.
Using an online calculator ensures accuracy, speed, and reproducibility—especially when you’re scanning a high volume of patients or training new staff.
Bonus: Simplify Your Workflow
At SonoCalc Lab, the goal is to make radiology tools simple, reliable, and fast. The TI-RADS calculator saves time, standardizes reporting, and reduces error risk.
👉 Try the calculator now at SonoCalcLab.com — or bookmark it for your next thyroid scan.