Validation of the modified 4-tiered categorization system through comparison with the 5-tiered categorization system of the 2015 American Thyroid Association guidelines for classifying small thyroid nodules on ultrasound
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Updated: Feb 24, 2026

A Swin Transformer-Based Model for Thyroid Nodule Detection in Ultrasound Images
Published on: April 21, 2023
Ji Hye Lee1, Kyunghwa Han1, Eun-Kyung Kim1
1Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul, Korea.
Background:
The purpose of this study was to validate the modified 4-tiered categorization system and to compare stratification of malignancy risk in small thyroid nodules with the 2015 American Thyroid Association (ATA) management guidelines.
Methods:
From January 2015 to December 2015, 737 thyroid nodules measured ≥ 1 cm and <2 cm were included in this study. Each nodule was assigned a category with the ultrasonographic patterns described by the 2015 ATA guidelines.
Results:
On univariate analysis, there was no difference of malignancy risk between low suspicion and very low suspicion nodules (P = .584). Therefore, we suggested a modified 4-tiered categorization, which combines very low suspicion and low suspicion nodules into the "revised low suspicion" category. Specificity, positive predictive value (PPV) and accuracy were higher with the modified 4-tiered categorization system (P < .001 for all).
Conclusion:
The modified 4-tiered categorization system allows more efficient management with better diagnostic performance than the 2015 ATA categorization system in small thyroid nodules.

