Role of ACR-TIRADS in risk stratification of thyroid nodules

Background: This study was performed to prospectively investigate the diagnostic reliability of the daily use of ACR-TIRADS classification system, in differentiating between a benign and a malignant lesion.Methods: In this prospective observational study, 50 patients with thyroid nodules underwent ultrasound examination and fine needle aspiration. The ultrasound studies were evaluated according to the ACR-TIRADS greyscale characteristics of composition, echogenicity, margins, shape, and echogenic foci. Each feature in a particular USG characteristic was scored and ACR-TIRADS categorization done from 1 to 5. This was compared to FNAC/histopathology findings and risk of malignancy was calculated for each feature and ACR-TIRADS category.Results: Of the 50 nodules included in the study, 38 were found to be benign and 12 were found to be malignant. Risk of malignancy for all ultrasound features showed an increasing trend with higher scored feature. Risk of malignancy for various features were as follows: Composition-cystic (0%), spongiform (0%), solid-cystic (0%) and solid (36%); echogenicity-anechoic(0%), hyperechoic (4%), isoechoic (11%), hypoechoic (47%) and markedly hypoechoic (100%); shape-wider-than-tall (21%) and taller-than-wide (66%); margins-smooth (18%), illdefined (0%), lobulated/irregular (38%) and extrathyroid extension (100%); echogenic foci-none (13%), large comet-tail artefacts (0%), macrocalcification (42%), rim calcification (50%) and punctate echogenic foci (50%). Amongst ACR-TIRADS(TR) categories TR1, TR2 and TR3 had 0% risk while TR4 had 30% and TR5 had 56% risk of malignancy with p value of 0.001.Conclusions: ACR-TIRADS is a high specific, accurate classification system for categorizing the thyroid nodules based on ultrasound features, for assessing the risk of malignancy