Korean J Radiol.  2018 Jun;19(3):534-541. 10.3348/kjr.2018.19.3.534.

Impact of Nodule Size on Malignancy Risk Differs according to the Ultrasonography Pattern of Thyroid Nodules

  • 1Department of Radiology, Gachon University Gil Medical Center, Incheon 21565, Korea.
  • 2Department of Radiology, GangNeung Asan Hospital, University of Ulsan College of Medicine, Gangneung 25440, Korea. nndgna@gmail.com
  • 3Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea.
  • 4Department of Radiology, Thyroid Center, Daerim St. Mary's Hospital, Seoul 07442, Korea.
  • 5Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 03080, Korea.


To test whether the impact of thyroid-nodule size on the malignancy risk differs according to the ultrasonography (US) patterns of nodules.
This study is a post hoc analysis using data from the Thyroid Imaging Reporting and Data System (TIRADS) multicenter retrospective study which included 2000 consecutive thyroid nodules (≥ 1 cm) with final diagnoses. A total of 2000 consecutive thyroid nodules from 1802 patients (1387 women and 613 men; mean age, 51.2 ± 12.2 years) were enrolled in this study. The malignancy risk of the nodules was assessed according to the nodule size and US patterns (Korean-TIRADS).
Overall, the malignancy risk did not increase as nodules enlarged. In high-suspicion nodules, the malignancy rate had no association with nodule size (p = 0.467), whereas in intermediate- or low-suspicion nodules there was a trend toward an increasing malignancy risk as the nodule size increased (p = 0.004 and 0.002, respectively). The malignancy rate of large nodules (≥ 3 cm) was higher than that of small nodules (< 3 cm) in intermediate-suspicion nodules (40.3% vs. 22.6%, respectively; p = 0.001) and low-suspicion nodules (11.3% vs. 7.0%, respectively; p = 0.035). There was a trend toward a decreasing risk and proportion of papillary carcinoma and an increasing risk and proportion of follicular carcinoma or other malignant tumors as nodule size increased (p < 0.001, respectively).
The impact of nodule size on the malignancy risk differed according to the US pattern. A large nodule size (≥ 3 cm) showed a higher malignancy risk than smaller nodules in intermediate- and low-suspicion nodules.


Thyroid; Thyroid nodule; Thyroid malignancy; Ultrasonography; Tumor size; Nodule size; Risk of malignancy; Malignancy risk; Pattern analysis; Imaging analysis; Imaging pattern; Imaging feature
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