Korean Society of Thyroid Radiology Thyroid Imaging, Reporting and Data System (K-TIRADS)
K-TIRADS is a reporting system designed by the Korean Society of Thyroid Radiology for ultrasound assessment of thyroid nodules and stratification of the requirement for FNA and malignancy. There is also stratification of indications for lymph node sampling.
This is a five-stage system using descriptive, pattern recognition findings on ultrasound, and size measurement.
A number of established benign nodules features (purely cystic/anechoic, comet tail artefact, spongiform) are included in the benign K-TIRADS 2 group.
Assessment of echogenicity, shape/contour and three specific suspicious ultrasound features (microcalcifications, nonparallel orientation [taller than wide], spiculated / microlobulated margin) determine categorization.
Partially cystic or isohyperechoic nodules are considered lower risk than solid hypoechoic nodules.
- K-TIRADS 1: no nodule
- K-TIRADS 2: benign
- K-TIRADS 3 (low): partially cystic / isohyperechoic with no suspicious features
- K-TIRADS 4 (intermediate): as for K-TIRADS 3 but with any suspicious features or as for K-TIRADS 5 without suspicious features
- K-TIRADS 5 (high): solid hypoechoic nodule with any suspicious features
Use of FNA / sampling is a combination of the suspicion above and size, unless there are obvious poor prognostic factors (extrathryoid extension or known distant metastases).
- K-TIRADS 2: if a spongiform nodule is ≥2 cm FNA is recommended
- K-TIRADS 3: ≥1.5 cm
- K-TIRADS 4: ≥1 cm
- K-TIRADS 5: ≥1 cm
Risk of malignancy
The overall risk of malignancy in the original 2016 paper was 0% for K-TIRADS 2, 7.8% for K-TIRADS 3, 25.4% for K-TIRADS 4 and 79.3% for K-TIRADS 5.
Sensitivity for malignancy for each stage is:
- K-TIRADS 2: 0%
- K-TIRADS 3: 19.2%
- K-TIRADS 4: 29.5%
- K-TIRADS 5: 51.3%
Comparison with other classification systems
A number of comparative studies of the systems 3-5 show the KSThR system has high sensitivity (71-95%) but variable-to-poor specificity (53-67%). The threshold for FNA / sampling is lower than most other systems, which results in high pick up rates but also consistently high unnecessary FNA rates, with only a 41% accuracy 4.
Excellent interobserver agreement regarding decision to biopsy has been shown (Cohen kappa 0.82) 6.
Lymph node assessment
K-TIRADS also describes the assessment of cervical lymph nodes which can be interrogated at the same time as thyroid lesions, both on ultrasound and CT.
Benign features include a normal hilar fatty echo and vascular pattern. Intermediate features include the loss of normal hilar structures and suspicious nodes show cystic/necrotic change, micro or macrocalcification, hyperechogenicity and abnormal peripheral or diffuse vasculature.
FNA is recommended for suspicious nodes >3 mm and intermediate nodes >5 mm (short diameter).
- 1. Shin JH, Baek JH, Chung J, Ha EJ, Kim JH, Lee YH, Lim HK, Moon WJ, Na DG, Park JS, Choi YJ, Hahn SY, Jeon SJ, Jung SL, Kim DW, Kim EK, Kwak JY, Lee CY, Lee HJ, Lee JH, Lee JH, Lee KH, Park SW, Sung JY. Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations. (2016) Korean journal of radiology. 17 (3): 370-95. doi:10.3348/kjr.2016.17.3.370 - Pubmed
- 2. Ting Xu, Ya Wu, Run-Xin Wu, Yu-Zhi Zhang, Jing-Yu Gu, Xin-Hua Ye, Wei Tang, Shu-Hang Xu, Chao Liu, Xiao-Hong Wu. Validation and comparison of three newly-released Thyroid Imaging Reporting and Data Systems for cancer risk determination. (2019) Endocrine. 64 (2): 299. doi:10.1007/s12020-018-1817-8 - Pubmed
- 3. Ting Xu, Ya Wu, Run-Xin Wu, Yu-Zhi Zhang, Jing-Yu Gu, Xin-Hua Ye, Wei Tang, Shu-Hang Xu, Chao Liu, Xiao-Hong Wu. Validation and comparison of three newly-released Thyroid Imaging Reporting and Data Systems for cancer risk determination. (2019) Endocrine. 64 (2): 299. doi:10.1007/s12020-018-1817-8 - Pubmed
- 4. Eun Ju Ha, Dong Gyu Na, Jung Hwan Baek, Jin Yong Sung, Ji-hoon Kim, So Young Kang. US Fine-Needle Aspiration Biopsy for Thyroid Malignancy: Diagnostic Performance of Seven Society Guidelines Applied to 2000 Thyroid Nodules. (2018) Radiology. 287 (3): 893-900. doi:10.1148/radiol.2018171074 - Pubmed
- 5. Grani, Giorgio, Lamartina, Livia, Ascoli, Valeria, Bosco, Daniela, Biffoni, Marco, Giacomelli, Laura, Maranghi, Marianna, Falcone, Rosa, Ramundo, Valeria, Cantisani, Vito, Filetti, Sebastiano, Durante, Cosimo. Reducing the Number of Unnecessary Thyroid Biopsies While Improving Diagnostic Accuracy: Toward the “Right” TIRADS. (2019) The Journal of Clinical Endocrinology & Metabolism. 104 (1): 95. doi:10.1210/jc.2018-01674 - Pubmed
- 6. Giorgio Grani, Livia Lamartina, Vito Cantisani, Marianna Maranghi, Piernatale Lucia, Cosimo Durante. Interobserver agreement of various thyroid imaging reporting and data systems. (2018) Endocrine Connections. 7 (1): 1. doi:10.1530/EC-17-0336 - Pubmed
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