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 five risk levels (TR1–TR5). Thyroid function testing with a TSH Calculator complements ultrasound risk stratification. Like PI-RADS for prostate and BI-RADS for breast, TI-RADS provides a standardized imaging lexicon that guides biopsy and follow-up decisions.
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 = 0 pts; hyperechoic/isoechoic = 1 pt; 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.