ACR TI-RADS Ultrasound Classification Explained: A Practical Guide for Sonographers

ACR TI-RADS is the language radiologists and sonographers use to communicate thyroid nodule risk — and using it correctly is one of the highest-value skills you can develop in thyroid scanning. The system is more nuanced than it first appears, and the difference between a TR3 and TR4 nodule can change whether a patient gets a biopsy.

This guide explains ACR TI-RADS 2017 in practical terms — how the point system works, what features matter, and when FNA is and isn't recommended.

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What Is ACR TI-RADS?

TI-RADS stands for Thyroid Imaging Reporting and Data System. The ACR (American College of Radiology) version published in 2017 uses a point-based scoring system across five feature categories. Points accumulate to assign a TR level (TR1–TR5), which determines whether FNA is recommended and at what size threshold.

Note: ACR TI-RADS (2017) is distinct from the Korean TIRADS and EU-TIRADS systems. SonoBuddy follows ACR TI-RADS 2017 as the US standard.

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The Five Feature Categories

TI-RADS scores each nodule across five feature categories. You select only one item from each category — the one that best describes the nodule.

Category 1: Composition

Feature	Points
Cystic or almost completely cystic	0
Spongiform	0
Mixed cystic and solid	1
Solid or almost completely solid	2

Spongiform = aggregated small cysts occupying > 50% of the nodule. This is always benign-appearing and scores 0 points regardless of other features.

Category 2: Echogenicity

Feature	Points
Anechoic	0
Hyperechoic or isoechoic	1
Hypoechoic	2
Very hypoechoic	3

Very hypoechoic = more hypoechoic than the adjacent strap muscles (not just hypoechoic relative to normal thyroid).

Category 3: Shape

Feature	Points
Wider than tall	0
Taller than wide	3

Measured on a transverse image. A taller-than-wide nodule has its longest dimension in the AP plane — associated with malignancy.

Category 4: Margin

Feature	Points
Smooth	0
Ill-defined	0
Lobulated or irregular	2
Extrathyroidal extension	3

Ill-defined margins in ACR TI-RADS score 0 (counterintuitive but correct). Only lobulated/irregular or extrathyroidal extension scores points.

Category 5: Echogenic Foci

Select all that apply (this is the only additive category):

Feature	Points
None or large comet-tail artifacts	0
Macrocalcifications	1
Peripheral (rim) calcifications	2
Punctate echogenic foci	3

Punctate echogenic foci are the sonographic correlate of microcalcifications — tiny bright dots without posterior shadowing (or with tiny comet-tail artifacts). These are the highest-risk finding in this category and are associated with papillary thyroid carcinoma.

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TI-RADS Level Assignment

Total Points	TI-RADS Level	Risk	Management
0	TR1 — Benign	No risk	No FNA
2	TR2 — Not suspicious	< 2%	No FNA
3	TR3 — Mildly suspicious	~5%	FNA if ≥ 2.5 cm; follow if ≥ 1.5 cm
4–6	TR4 — Moderately suspicious	~5–20%	FNA if ≥ 1.5 cm; follow if ≥ 1.0 cm
≥ 7	TR5 — Highly suspicious	> 20%	FNA if ≥ 1.0 cm; follow if ≥ 0.5 cm

Follow = ultrasound surveillance (typically 1 year, then 1–2 years, then 3–5 years). Specific intervals depend on TR level and nodule size.

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Worked Example

A solid, hypoechoic, wider-than-tall nodule with irregular margins and punctate echogenic foci:

Feature	Selection	Points
Composition	Solid	2
Echogenicity	Hypoechoic	2
Shape	Wider than tall	0
Margin	Irregular	2
Echogenic foci	Punctate	3
Total		9 → TR5

This nodule would be classified as TR5 — highly suspicious. FNA is recommended if ≥ 1.0 cm.

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What TI-RADS Does NOT Apply To

ACR TI-RADS is designed for incidentally discovered thyroid nodules in adults. It should not be applied to:

• Pediatric patients (separate guidelines)
• Patients with known thyroid malignancy
• Post-thyroidectomy remnant nodules
• Nodules with clinical high-risk features (palpable firm mass, rapid growth, adenopathy)

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Pure Cysts and the Comet-Tail Artifact

Purely cystic nodules and those with large comet-tail artifacts (≥ 1 mm posterior reverberation echoes) are classified as TR1 or TR2 (benign or not suspicious) regardless of other features. Comet-tail artifacts indicate colloid, not calcification — they are a reassuring finding.

Do not confuse comet-tail artifacts with:

• Punctate echogenic foci (tiny, no posterior reverberation ≥ 1 mm)
• Macrocalcifications (large, strong shadow)

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Multiple Nodules

When multiple nodules are present:

• Score each nodule independently
• Report the one or two highest TR-level nodules
• You do not need to score every nodule if there are many — focus on the most suspicious

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Reporting Format

When documenting TI-RADS:

1. Location — right/left lobe, upper/mid/lower pole, isthmus
2. Size — maximum diameter in three planes
3. TI-RADS score — list each feature and points, total, TR level
4. Management recommendation — FNA vs. follow-up vs. no action

Example: "Right lobe, mid pole. 1.2 cm (1.2 × 0.9 × 0.8 cm). Solid (2), hypoechoic (2), wider than tall (0), smooth margin (0), punctate echogenic foci (3) = 7 points → TR5 (highly suspicious). FNA recommended."

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Quick Reference: TI-RADS Points at a Glance

Category	Max Points
Composition	2
Echogenicity	3
Shape	3
Margin	3
Echogenic foci	3
Maximum possible	14

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Access TI-RADS Reference in SonoBuddy

SonoBuddy's thyroid pathology section includes a TI-RADS scoring guide with all five feature categories, point values, and management thresholds — accessible in seconds during your thyroid scan.

Open SonoBuddy → Pathologies → Thyroid Nodule.

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Reference: Tessler FN, Middleton WD, Grant EG, et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee. J Am Coll Radiol. 2017;14(5):587-595.

SonoBuddy is a reference tool, not a diagnostic authority. Clinical decisions must involve the ordering provider and interpreting physician.