Diagnostic performance of the EU TI-RADS and ACR TI-RADS scoring systems in predicting thyroid malignancy

Introduction: Several ultrasound scoring systems have been developed to stratify the risk of malignancy of thyroid nodules, including ACR (American College of Radiology) and EU (European) TI-RADS. This study aimed to assess the diagnostic performance of these two classifications using histology as a reference standard. Methods: It was a single-centre, retrospective study including 156 patients who underwent thyroidectomy. Ultrasound data of 198 nodules (99 malignant nodules and 99 benign nodules) were analysed. Both classifications were applied for all nodules. Results: Ultrasound criteria associated with malignancy were solid composition (OR=7.81; p < 10(-3)), hypoechoic character (OR=16.42; p < 10(-3)), irregular contours (OR=7.47; p < 10(-3)), taller-than- wide shape (OR= 3.58; p = 0.02), microcalcifications (OR=3.02; p =.006) and the presence of cervical adenopathy (OR=3.89; p =.006). The prevalence of malignancy was 15.5%, 69% and 76.9% for EU TI-RADS categories 3, 4 and 5, respectively. It was 33.3%, 57% and 91.1% for ACR TI-RADS categories 3, 4 and 5, respectively. For category 5, EU TI-RADS and ACR TI-RADS had sensitivities of 60% and 41%, specificities of 82% and 96%, respectively. For categories 4 and 5 combined, the diagnostic performance of these two classification systems became comparable with a sensitivity of 89% and 86% for EU-TIRADS and ACR-TIRADS, respectively. The area under the ROC curve was 0.81 for the EU TI-RADS classification and 0.82 for the ACR TI-RADS classification. Conclusions: EU TI-RADS and ACR TI-RADS scoring systems seem to be comparable in predicting malignancy in thyroid nodules.