Abstract: Two types of risk-stratification system, including a grading system and a scoring system, have been used for the effective management of thyroid nodules on ultrasonography. The concept of the Thyroid Imaging Reporting and Data System (TI-RADS), based on the quantitative scoring system, was introduced at the beginning of the 21st century, 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. This comprehensive review provided a developmental overview of the use of risk-stratification systems in thyroid nodules, including TI-RADS proposals, analyzed advantages and disadvantages of TI-RADS, and described the future developmental direction of TI-RADS for the personalized and optimized management of thyroid nodules.

Key words: Thyroid, Ultrasound, Grading, Scoring