Endocrinol Metab.  2021 Oct;36(5):1111-1120. 10.3803/EnM.2021.1208.

Comparison of Korean vs. American Thyroid Imaging Reporting and Data System in Malignancy Risk Assessment of Indeterminate Thyroid Nodules

  • 1Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
  • 2Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
  • 3Department of Internal Medicine, Uijeongbu Eulji Medical Center, Eulji University School of Medicine, Uijeongbu, Korea
  • 4Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea


The management of cytologically indeterminate thyroid nodules is challenging for clinicians. This study aimed to compare the diagnostic performance of the Korean Thyroid Imaging Reporting and Data Systems (K-TIRADS) with that of the American College of Radiology (ACR)-TIRADS for predicting the malignancy risk of indeterminate thyroid nodules.
Thyroid nodules diagnosed by fine-needle aspiration (FNA) followed by surgery or core needle biopsy at a single referral hospital were enrolled.
Among 200 thyroid nodules, 78 (39.0%) nodules were classified as indeterminate by FNA (Bethesda category III, IV, and V), and 114 (57.0%) nodules were finally diagnosed as malignancy by surgery or core needle biopsy. The area under the curve (AUC) was higher for FNA than for either TIRADS system in all nodules, while all three methods showed similar AUCs for indeterminate nodules. However, for Bethesda category III nodules, applying K-TIRADS 5 significantly increased the risk of malignancy compared to a cytological examination alone (50.0% vs. 26.5%, P=0.028), whereas applying ACR-TIRADS did not lead to a change.
K-TIRADS and ACR-TIRADS showed similar diagnostic performance in assessing indeterminate thyroid nodules, and K-TIRADS had beneficial effects for malignancy prediction in Bethesda category III nodules.


Thyroid imaging reporting and data systems; Thyroid neoplasms; Thyroid nodule; Thyroid ultrasound; Thyroid guidelines


  • Fig. 1 Receiver operating characteristic curve of Korean Thyroid Imaging Reporting and Data System (K-TIRADS), American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS), and fine-needle aspiration (FNA) in (A) all thyroid nodules and (B) Bethesda categories III, IV, and V.

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Comparison of Thyroid Imaging Reporting and Data Systems in Malignancy Risk Stratification of Indeterminate Thyroid Nodules
Bo Hyun Kim
Endocrinol Metab. 2021;36(5):974-976.    doi: 10.3803/EnM.2021.1287.


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