From the Guidelines
The Thyroid Imaging Reporting and Data System (TIRADS) is a crucial tool for risk stratification of thyroid nodules detected on ultrasound, and it is based on extensive data collected over the past two decades on US assessment of TNs, as stated in the study by 1. The TIRADS system assigns points based on five ultrasound features: composition, echogenicity, shape, margin, and echogenic foci.
- Composition can be cystic (0 points), spongiform (0 points), mixed cystic-solid (1 point), or solid (2 points).
- Echogenicity is scored as anechoic (0 points), hyperechoic/isoechoic (1 point), hypoechoic (2 points), or very hypoechoic (3 points).
- Shape is either wider-than-tall (0 points) or taller-than-wide (3 points).
- Margins can be smooth (0 points), ill-defined (0 points), lobulated/irregular (2 points), or extra-thyroidal extension (3 points).
- Echogenic foci include none/large comet-tail artifacts (0 points), macrocalcifications (1 point), peripheral calcifications (2 points), or punctate echogenic foci (3 points). The total point score determines the TIRADS level (TR1-TR5) and subsequent management, with higher scores indicating greater risk of malignancy and lower thresholds for biopsy, as supported by the study by 1. The primary goal of TIRADS is to standardize the terminology used in thyroid US reports and minimize unnecessary fine needle aspiration (FNA), such as those resulting in benign/nonneoplastic cytology, as mentioned in the study by 1. The system helps standardize thyroid nodule evaluation and reduces unnecessary biopsies while ensuring potentially malignant nodules are appropriately investigated, as stated in the study by 1. In clinical practice, the TIRADS system is used in conjunction with other guidelines, such as the American Thyroid Association guidelines, to classify differentiated thyroid carcinomas (DTCs) as low-, intermediate-, and high-risk, and to determine the need for radioiodine treatment and tailor postoperative management for DTC, as mentioned in the study by 1.
From the Research
TIRADS Criteria
The Thyroid Imaging Reporting and Data System (TIRADS) is a standardized approach for the risk stratification of thyroid nodules. The criteria for TIRADS include:
- Scoring the number or combination of suspicious ultrasound features to calculate the risk of malignancy in thyroid nodules 2
- Classification of nodules into different categories based on their ultrasound features, with recommendations for further diagnostic steps 3, 4
- Use of a points-based approach to lead to clear management recommendations for nodules 5
TIRADS Categories
The TIRADS categories are used to stratify the risk of malignancy in thyroid nodules. The categories include:
- Category 5: highly suspicious nodules with a higher risk of malignancy 6
- Category 4: suspicious nodules with a moderate risk of malignancy 3
- Category 3: nodules with a low risk of malignancy 3
- Category 2: benign nodules with a very low risk of malignancy 3
- Category 1: non-diagnostic or incomplete ultrasound evaluation 4
Diagnostic Performance of TIRADS
The diagnostic performance of TIRADS has been evaluated in several studies. The results show that:
- TIRADS has a high sensitivity and negative predictive value for the diagnosis of thyroid carcinoma 3
- The prevalence of malignancy rises with increasing category levels of TIRADS 2
- TIRADS seems to be a promising tool to reliably assess the risk of malignancy of small thyroid nodules 2
- The highest negative predictive value was found for ACR TI-RADS and the highest positive predictive value for Kwak-TIRADS 2