title: A Multicenter Prospective Validation Study for the Korean Thyroid Imaging Reporting and Data System in Patients with Thyroid Nodules.
abstract: To validate a new risk stratification system for thyroid nodules, the Korean Thyroid Imaging Reporting and Data System (K-TIRADS), using a prospective design.
  
  
  
  From June 2013 to May 2015, 902 thyroid nodules were enrolled from four institutions. The type and predictive value of ultrasonography (US) predictors were analyzed according to the combination of the solidity and echogenicity of nodules; in addition, we determined malignancy risk and diagnostic performance for each category of K-TIRADS, and compared the efficacy of fine-needle aspiration (FNA) with a three-tier risk categorization system published in 2011.
  
  
  
  The malignancy risk was significantly higher in solid hypoechoic nodules, as compared to partially cystic or isohyperechoic nodules (each p < 0.001). The presence of any suspicious US features had a significantly higher malignancy risk (73.4%) in solid hypoechoic nodules than in partially cystic or isohyperechoic nodules (4.3-38.5%; p < 0.001). The calculated malignancy risk in K-TIRADS categories 5, 4, 3, and 2 nodules were 73.4, 19.0, 3.5, and 0.0%, respectively; and the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for malignancy were 95.5, 58.6, 44.5, 96.9, and 69.5%, respectively, in K-TIRADS categories 4 and 5. The efficacy of FNA for detecting malignancy based on K-TIRADS was increased from 18.6% (101/544) to 22.5% (101/449), as compared with the three-tier risk categorization system (p < 0.001).
  
  
  
  The proposed new risk stratification system based on solidity and echogenicity was useful for risk stratification of thyroid nodules and the decision for FNA. The malignancy risk of K-TIRADS was in agreement with the findings of a previous retrospective study.
authors: Department of Radiology, Ajou University School of Medicine, Suwon 16499, Korea.
authors: Eun Ju
authors: EJ
authors: Ha
authors: Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul 05030, Korea.
authors: Won-Jin
authors: WJ
authors: Moon
authors: Department of Radiology, Human Medical Imaging and Intervention Center, Seoul 06524, Korea.
authors: Dong Gyu
authors: DG
authors: Na
authors: Department of Radiology, Ansan Hospital, Korea University School of Medicine, Ansan 15355, Korea.
authors: Young Hen
authors: YH
authors: Lee
authors: Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul 05030, Korea.
authors: Nami
authors: N
authors: Choi
authors: Department of Radiology, Human Medical Imaging and Intervention Center, Seoul 06524, Korea.; Department of Radiology, New Korea Hospital, Gimpo 10086, Korea.
authors: Soo Jin
authors: SJ
authors: Kim
authors: Department of Radiology, Chung-Ang University Hospital, Seoul 06973, Korea.
authors: Jae Kyun
authors: JK
authors: Kim
mesh_terms: D000328:Adult; D044963:Biopsy, Fine-Needle / Q000379:methods; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012107:Research Design; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000473:pathology; D014463:Ultrasonography / Q000379:methods
keywords: Core needle biopsy; Fine needle aspiration; Malignancy risk; Risk stratification; Thyroid cancer; Thyroid imaging reporting and data system; Thyroid neoplasm; Thyroid nodules; Ultrasonography