Scoring

Feature points

• Composition: cystic/spongiform 0; mixed cystic-solid 1; solid/almost solid 2.
• Echogenicity: anechoic 0; hyper/isoechoic 1; hypoechoic 2; very hypoechoic 3.
• Shape: wider-than-tall 0; taller-than-wide 3, assessed on the transverse image.
• Margin: smooth or ill-defined 0; lobulated/irregular 2; extra-thyroidal extension 3.
• Echogenic foci: none or large comet-tail 0; macrocalcification 1; rim calcification 2; punctate echogenic foci 3.

Category

• TR1: 0 points, benign.
• TR2: 2 points, not suspicious.
• TR3: 3 points, mildly suspicious.
• TR4: 4-6 points, moderately suspicious.
• TR5: 7 or more points, highly suspicious.
• Predominantly cystic or spongiform nodules are considered benign patterns and are automatically TR1.

Follow-Up / FNA

Thresholds

• TR3: follow at 1.5 cm or larger; FNA at 2.5 cm or larger.
• TR4: follow at 1.0 cm or larger; FNA at 1.5 cm or larger.
• TR5: follow at 0.5 cm or larger; FNA at 1.0 cm or larger.

Follow-up schedule

• TR3: ultrasound at 1, 3, and 5 years.
• TR4: ultrasound at 1, 2, 3, and 5 years.
• TR5: annual ultrasound up to 5 years.

Approximate malignancy risk

• TR1: 0.3%; TR2: 1.5%; TR3: 4.8%; TR4: 9.1%; TR5: 35%.

Reporting Pearls

Multiple nodules

• Score and report the four highest-scoring nodules, not necessarily the four largest.
• If biopsy is needed, sample the two nodules with the highest TI-RADS scores.
• If nodules have the same TI-RADS category, use largest size as the tie-breaker.

Significant growth

• More than 20% increase and more than 2 mm increase in at least two dimensions.
• Or more than 50% increase in volume.
• If TI-RADS category increases on follow-up, repeat ultrasound the following year.

Pitfalls

• Punctate echogenic foci may be true microcalcifications or inspissated colloid; colloid is not a high-risk feature.
• Frank invasion of surrounding structures gets extra-thyroidal extension points, but subtle/minimal suspected extension should be interpreted cautiously.