Risk Stratification of Thyroid Nodules on Ultrasonography: Current Status and Perspectives

Background: Two types of risk-stratification system-a qualitative grading system or a quantitative scoring system-have been used for the effective management of thyroid nodules on ultrasonography. Summary: The concept of the Thyroid Imaging Reporting and Data System (TI-RADS), based on the quantitative scoring system, was introduced in the late 2000s, and its format has been constantly evolving and developing. Understanding the role and appropriate utilization of risk-stratification systems including TI-RADS could facilitate the effective interpretation and communication of thyroid ultrasonography findings among referring physicians and cytopathologists. Conclusion: This comprehensive review provides a developmental overview of the use of risk-stratification systems in thyroid nodules, including TI-RADS proposals, and describes the future developmental direction of TI-RADS for the personalized and optimized management of thyroid nodules.