TIRADS CALCULATOR FOR THYROID NODULES

Risk of Thyroid Malignancy depending on TIRADS score

• TR 1 thyroid nodules have a 0.3 % risk of malignancy.
•  TR 2 thyroid nodules have a 1.5 % risk of malignancy.
• TR 3 thyroid nodules have a 4.8 % risk of malignancy.
• TR 4 thyroid nodules have a 9.1 % risk of malignancy.
• TR 5 thyroid nodules have a 35 % risk of malignancy.

Caveats for Thyroid Ultrasound Calculator

• If rim calcifications obscure the nodule completely, choose composition to be “solid” and echogenicity to be “isoechoic”.
• If the margin cannot be determined, choose “ill-defined margin”.
• If echogenicity cannot be determined, choose “isoechoic”.
• If composition cannot be determined, choose “solid”.
• Punctate echogenic foci and taller-than-wide features have the highest points so carefully evaluate these.

Key points from the original TIRADS article:

Composition

Cystic or almost completely cystic nodules are generally benign, as are spongiform nodules predominantly composed of small cystic spaces. Solid components with suspicious characteristics may warrant further evaluation for malignancy.

Echogenicity

Echogenicity evaluation involves comparing a nodule’s reflectivity to adjacent thyroid tissue, except for very hypoechoic nodules where strap muscles serve as a reference point. Special consideration is given to anechoic nodules.

Shape

A taller-than-wide shape, when assessed in the axial plane by comparing height and width measurements, can be highly specific for malignancy.

Margin

Ill-defined or irregular margins, especially with protrusions or lobulations, should raise suspicion. Extension beyond the thyroid border should also be considered.

Echogenic Foci

Different types of echogenic foci carry varying levels of suspicion. Punctate echogenic foci within solid components are particularly concerning and should be evaluated in conjunction with other features.

Papillary Thyroid Microcarcinomas

Biopsy of nodules smaller than 1 cm is generally not recommended; however, exceptions may be made based on specific circumstances. Guidelines recommend against routine biopsy of such small nodules unless actively surveilling, ablating, or considering lobectomy for papillary microcarcinomas.

Measurement and Documentation

Accurate sizing and detailed documentation of nodule location are crucial for monitoring and comparison over time.

Definition of Growth

Significant enlargement is defined as a 20% increase in at least two nodule dimensions with a minimal increase of 2 mm or a 50% or greater increase in volume.

Timing of Follow-Up Sonograms

• Optimal spacing for follow-up sonograms for nodules not meeting FNA size criteria lacks consensus in the literature.
• Scanning intervals of less than 1 year are generally not recommended, except for proven cancers under active surveillance.
• Follow-up intervals should be based on the nodule’s ACR TI-RADS level, with more suspicious lesions requiring additional sonograms.
• For TR5 lesions, annual scans for up to 5 years are recommended.
• For TR4 lesions, scans at 1, 2, 3, and 5 years are advised.
• TR3 lesions may undergo follow-up imaging at 1, 3, and 5 years.
• Imaging can be discontinued at 5 years if there is no size change, indicative of a benign behavior.
• Management of nodules enlarging significantly but remaining below FNA size threshold at 5 years lacks published guidance, but continued follow-up is likely required.
• If a nodule’s ACR TI-RADS level increases on follow-up, the next sonogram should be scheduled in 1 year regardless of its initial level.

Number of Nodules to Biopsy

Biopsy of two nodules with the highest suspicious appearance is recommended to avoid unnecessary procedures and patient discomfort.

Assessment of Cervical Lymph Nodes

Specific features indicating metastasis should prompt FNA of suspicious nodes along with up to two nodules meeting biopsy criteria based on the ACR TI-RADS guidelines.

Ultrasound Thyroid Score Explained

For a more detailed guide with examples, refer to the dedicated article here:

TIRADS ACR : What radiologists need to know!

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