Ultrasound-guided fine needle aspiration biopsy of the thyroid nodule is the standard procedure to make a diagnosis of malignancy. However, the number of FNACs that the patient can be subjected to has to be taken into consideration. The various risk stratification systems or Thyroid Imaging Reporting and Data Systems (TIRADSs) serve as a guide to this conundrum.  

A systematic review and meta-analysis was conducted to assess the diagnostic performance of biopsy criteria in four society ultrasonography risk stratification systems (RSSs) used to evaluate thyroid nodules measuring 1 cm or more in size.¹ These included the American College of Radiology Thyroid Imaging Reporting and Data System ((ACR)- TIRADS), the American Thyroid Association (ATA) system, the European (EU)-TIRADS, and the 2016 and 2021 Korean (K)-TIRADS. After screening more than 1000 studies, 11 studies with 27,250 nodules were included for the final analysis.

When the American biopsy criteria were examined, the ACR-TIRADS system had a pooled sensitivity of 82% and a specificity of 60%, while the ATA system had a pooled sensitivity and specificity of 89% and 34% respectively. The European criteria (EU-TIRADS) had a pooled sensitivity and specificity of 89% and 42%, respectively. The Korean system (K-TIRADS) had a pooled sensitivity of 96% and specificity of 21%. When the 2021 K-TIRADS1.5 (1.5-cm size cut-off for intermediate-suspicion nodules) was evaluated, the sensitivity and specificity were 76% and 50%.

The unnecessary biopsy rate defined as “the proportion of biopsy-confirmed benign nodules among all benign nodules” was also determined for all the four systems as a secondary outcome of the study. The pooled unnecessary biopsy rate of the ACR-TIRADS was 41%; it was 65% for the ATA system, 68% for EU-TIRADS and 79% for 2016 K-TIRADS system. The unnecessary biopsy rate was 50% for the 2021 K-TIRADS1.5.

The present study evaluated the diagnostic performance of four commonly used systems and the results published in the journal Endocrinology and Metabolism showed that the 2021 K-TIRADS1.5 system had a markedly lower unnecessary biopsy rate compared to the 2016 K-TIRADS system and also had a suitable diagnostic sensitivity. Therefore, using the 2021 K-TIRADS criteria may reduce “the potential harm due to unnecessary biopsies” of the benign thyroid nodules.

Reference

1. Joo L, et al. Diagnostic performance of ultrasound-based risk stratification systems for thyroid nodules: a systematic review and meta-analysis. Endocrinol Metab (Seoul). 2023 Feb;38(1):117-128. doi: 10.3803/EnM.2023.1670.