ACR TI-RADS Overview
The ACR TI-RADS (Thyroid Imaging Reporting and Data System) is a points-based system for risk stratifying incidentally discovered thyroid nodules on ultrasound. Published by Tessler et al. in 2017, it assigns points across five sonographic categories and stratifies nodules into 5 risk levels (TR1–TR5).
How to Use This Calculator
Score each of the five ultrasound feature categories for your thyroid nodule:
- Composition — Select the predominant composition (cystic/spongiform = 0 pts; mixed = 1 pt; solid = 2 pts). A purely spongiform nodule is benign and requires no further workup.
- Echogenicity — Compare to adjacent thyroid parenchyma. Anechoic/hyperechoic = 1 pt; isoechoic = 2 pts; hypoechoic = 2 pts; very hypoechoic = 3 pts.
- Shape — Wider-than-tall (oval/round) = 0 pts; taller-than-wide (AP diameter > transverse) = 3 pts. This must be assessed on a transverse image.
- Margin — Smooth/ill-defined = 0 pts; lobulated/irregular = 2 pts; extra-thyroidal extension = 3 pts.
- Echogenic Foci — None/large comet-tail artifacts = 0 pts; macrocalcifications = 1 pt; peripheral calcifications = 2 pts; punctate echogenic foci = 3 pts. Multiple types? Score only the highest.
Sum the points across all five categories to get your total score and TI-RADS level. The calculator then provides the ACR-recommended FNA and follow-up size thresholds for that level.
TI-RADS Levels and Management
| Level | Points | Risk | FNA if ≥ | Follow-up if ≥ |
|---|---|---|---|---|
| TR1 — Benign | 0 | Benign | No FNA | No follow-up |
| TR2 — Not Suspicious | 2 | <2% | No FNA | No follow-up |
| TR3 — Mildly Suspicious | 3 | ~5% | ≥2.5 cm | ≥1.5 cm |
| TR4 — Moderately Suspicious | 4–6 | ~5–20% | ≥1.5 cm | ≥1 cm |
| TR5 — Highly Suspicious | ≥7 | >20% | ≥1 cm | ≥0.5 cm |
High-Risk Features (Suspicious for Malignancy)
Features most associated with malignancy: taller-than-wide shape (3 pts), punctate echogenic foci/microcalcifications (3 pts), very hypoechoic echogenicity (3 pts), extra-thyroidal extension (3 pts), lobulated/irregular margin (2 pts). Papillary thyroid cancers classically show microcalcifications and taller-than-wide morphology.
Interpreting Your TI-RADS Result
A TI-RADS level drives two separate management decisions: whether to recommend FNA biopsy, and whether to recommend follow-up imaging. Both thresholds are size-dependent. Key interpretation principles:
- TR1 and TR2: No FNA and no follow-up are needed. TR1 (0 points) represents a benign nodule such as a simple cyst or spongiform nodule. TR2 (2 points) is not suspicious. These findings should be documented but require no further sonographic workup.
- TR3 (mildly suspicious, 3 pts): FNA is only warranted if the nodule is ≥2.5 cm. For nodules 1.5–2.4 cm, follow-up ultrasound at 1, 3, and 5 years is recommended. Nodules under 1.5 cm need no action. The estimated malignancy rate for TR3 is approximately 5%.
- TR4 (moderately suspicious, 4–6 pts): FNA threshold drops to ≥1.5 cm; follow-up applies for nodules ≥1.0 cm. Malignancy risk is roughly 5–20%. Multiple suspicious features (e.g., solid + hypoechoic + lobulated margin) commonly aggregate here.
- TR5 (highly suspicious, ≥7 pts): FNA is recommended at ≥1.0 cm; follow-up for nodules ≥0.5 cm. Malignancy risk exceeds 20%. A nodule reaching TR5 with features like taller-than-wide shape, punctate echogenic foci, and very hypoechoic echogenicity carries the highest malignancy probability and warrants prompt evaluation.
- Growth on follow-up: Regardless of initial TI-RADS level, nodule growth of ≥20% in at least 2 dimensions (with a minimum increase of 2 mm) during follow-up is an indication to escalate management, typically to FNA even if the original size was below threshold.
Always integrate TI-RADS findings with clinical context: prior head/neck radiation, family history of thyroid cancer, rapidly enlarging nodule, new hoarseness, or cervical lymphadenopathy may warrant more aggressive workup independent of TI-RADS level.
Limitations & Considerations
ACR TI-RADS has important limitations clinicians should be aware of:
- Inter-observer variability: Sonographic feature classification — particularly echogenicity, margin characterization, and the distinction between peripheral calcifications and macrocalcifications — carries meaningful inter-reader variability. TI-RADS scores can differ between readers on the same nodule.
- Not validated in pediatric patients: The ACR TI-RADS system was developed for adult patients. Thyroid malignancy rates in pediatric nodules are higher than in adults; apply ATA Pediatric Guidelines instead for patients under 18.
- Does not replace clinical judgment: High-risk clinical features (radiation history, rapid growth, lymphadenopathy, family history of medullary thyroid cancer or MEN2) may justify biopsy below ACR size thresholds. TI-RADS guides, it does not dictate.
- Multinodular goiter: When multiple nodules are present, each should be scored independently. The highest TI-RADS level drives management for that gland. Not all nodules in a multinodular goiter require individual evaluation — prioritize the largest and most suspicious.
- Comet-tail artifacts vs. punctate echogenic foci: Large comet-tail artifacts (reverberation artifact from colloid) score 0 points and are benign. True punctate echogenic foci (microcalcifications) score 3 points. Distinguishing these on ultrasound requires experience.
References
Tessler FN, 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.
Middleton WD, et al. Multi-institutional Analysis of Thyroid Nodule Risk Stratification Using the American College of Radiology Thyroid Imaging Reporting and Data System. AJR Am J Roentgenol. 2017;208(6):1331–1341.
American Thyroid Association Guidelines Task Force. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2016;26(1):1–133.