Table 1.

ACR TI-RADS and revised thyroid nodule size criteria

Category	ACR TI-RADS	Strategy 1 [9]	Strategy 2 [10]
TR1 (benign)	No FNAB	No FNAB	> 4.0 cm: FNAB 1.0–4.0 cm: Follow-up
TR2 (not suspicious)	No FNAB	No FNAB	> 4.0 cm: FNAB 1.0–4.0 cm: Follow-up
TR3 (mildly suspicious)	≥ 2.5 cm: FNAB ≥ 1.5 cm: Follow-up	≥ 1.5 cm: FNAB	≥ 1.5 cm: FNAB 1.0–1.5 cm: Follow-up
TR4 (moderately suspicious)	≥ 1.5 cm: FNAB ≥ 1.0 cm: Follow-up	≥ 1.0 cm: FNAB	≥ 1.0 cm: FNAB ≥ 0.5 cm Follow-up
TR5 (highly suspicious)	≥ 1.0 cm: FNAB ≥ 0.5 cm: Follow-up	≥ 1.0 cm: FNAB ≥ 0.5 cm: Follow-up	≥ 1.0 cm: FNAB 0.5–0.9 cm: Consider FNAB ≥ 0.5 cm Follow-up

Abbreviations: ACR, American College of Radiology; FNAB, fine needle aspiration biopsy; TI-RADS, Thyroid Imaging Reporting and Data System