Reliability of Thyroid Imaging Reporting and Data System (TIRADS) Classification in Differentiating Benign from Malignant Thyroid Nodules

Background: Ultrasonography (US) is the best diagnostic tool in the initial assessment of thyroid nodule. Giving its appropriateness and accessibility, ultrasound-based thyroid imaging reporting and data systems (TIRADS) classifications have been developed with main goal to standardize reporting and facilitate communication between practitioners, and to indicate when fine-needle aspiration biopsy (FNAB) should be performed. Objective: To determine the reliability of Russ’ modified TIRADS classification in predicting thyroid malignancy. Materials and Methods: It was a cross sectional study carried out at Centre Hospitalier de Lagny, Marne La Vallée (France). Consecutive records of patients with focal thyroid nodules on ultrasound (US) for which US-guided FNAB was performed and pathology results were available, from January 2007 to August 2012, were selected for review. The risk of malignancy of each TIRADS category was determined and correlation with pathology assessed. Statistical performances of some US features were also assessed. The threshold for statistical significance was set at 0.05. Results: A total of 430 records of patients were eligible. Twenty-three out of 430 (5.3%) nodules were malignant. The risk of malignancy of the TIRADS categories were as follows: TIRADS2 0%, TIRADS3 2.2%, TIRADS4A 5.9%, TIRADS4B 57.9%, TIRADS5 100% (Gamma statistic = 0.85; Spearman correlation = 0.30, Pearson’s R = 0.37, p < 0.001). Some US features were associated with a higher risk of malignancy: irregular contours (OR = 22.4), taller-than-wide shape (OR = 19.5), microcalcifications (OR = 15.2), and marked hypoechogenicity (OR = 12.7). Conclusion: Russ’ modified TIRADS classification is reliable in predicting thyroid malignancy. More evidence is nevertheless necessary for widespread adoption and use.