From the Guidelines
For a TI-RADS category 4 thyroid nodule measuring 1.2 cm, follow-up ultrasound is recommended in 6-12 months, with subsequent annual ultrasound surveillance for at least 3-5 years if the nodule remains stable. This recommendation is based on the moderate suspicion for malignancy (5-20%) associated with TI-RADS 4 nodules, as suggested by the American College of Radiology Appropriateness Criteria 1. Fine needle aspiration (FNA) biopsy should also be considered for this nodule since it exceeds 1 cm in size, which is the typical threshold for biopsy of TI-RADS 4 nodules, according to the ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of thyroid cancer 2, 3. Some key points to consider during follow-up include:
- Monitoring for concerning changes such as increased size (>20% increase in two dimensions or >50% increase in volume)
- Development of suspicious features like irregular margins, microcalcifications, or abnormal vascularity
- Earlier intervention or repeat biopsy may be warranted if such changes occur, regardless of the original follow-up timeline It is essential to discuss the nodule's nature and the follow-up plan with a physician, especially if an FNA has not been performed yet, as it provides more definitive information about the nodule's nature 2.
From the Research
Thyroid Ultrasound Follow-up for TI-RADS Category 4 Nodules
- The American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) provides a framework for assessing the malignancy risk of thyroid nodules 4.
- For TI-RADS category 4 nodules, the current recommendation is to perform fine-needle aspiration (FNA) for nodules ≥1.5 cm in size, but there is no clear guidance on the follow-up interval for smaller nodules 4.
- A study published in 2022 found that a TI-RADS score of ≥4 had an 84% positive predictive value (PPV) for malignancy, suggesting that category 4 nodules may require closer follow-up 5.
- Another study published in 2019 found that the ACR TI-RADS system had high diagnostic value in differentiating malignant from benign thyroid nodules in a pediatric population, with a high likelihood of malignancy associated with TI-RADS category 4 or 5 nodules 6.
- However, there is limited evidence specifically addressing the follow-up interval for TI-RADS category 4 nodules of 1.2 cm size, and the optimal follow-up strategy may depend on individual patient factors and clinical judgment 7, 8.
Factors Influencing Follow-up Recommendations
- Nodule size: Larger nodules are generally considered to be at higher risk of malignancy and may require more frequent follow-up 4, 5.
- Patient age and medical history: Pediatric patients and those with a history of radiation exposure may be at higher risk of thyroid cancer and may require more frequent follow-up 6.
- Ultrasound features: Nodules with suspicious ultrasound features, such as irregular margins or microcalcifications, may require more frequent follow-up 8.
Current Recommendations
- The ACR TI-RADS system recommends FNA for TI-RADS category 4 nodules ≥1.5 cm in size, but does not provide specific guidance on the follow-up interval for smaller nodules 4.
- The American Thyroid Association (ATA) recommends annual ultrasound follow-up for nodules ≥1 cm in size with suspicious features, but does not provide specific guidance on the follow-up interval for TI-RADS category 4 nodules 7.