MON-526 Comparison of ACR-TIRADS to American Thyroid Association Guidelines: Can We Choose Wisely Without Missing Malignancy?

Thyroid ultrasound has been widely used to determine which nodules need further work up. The goal of this study was to apply the new ACR-TIRADs criteria to a retrospective data set and compare the outcomes to the ATA scoring system. Methods: In a retrospective study, ultrasonographic images of the all nodules biopsied in 2015 were reviewed by radiologists, blinded to fine needle aspiration (FNA) biopsy result, using a checklist to report the image. The checklist was prepared based on 2015 ATA guideline. The ultrasonographic characteristics of thyroid nodules were compared with the result of biopsy to determine positive predictive value (PPV), negative predictive value (NPV), sensitivity and specificity of checklist in predicting malignancy. These results were published previously. The same data was then reviewed using the ACR-TiRADS tool to assess the number of US and FNA that would been avoided and the number of non-benign cytologies that would have been avoided had these criteria guided care in 2015. Results: 419 thyroid nodules were reviewed 7.1% were malignant, 10.3% were FLUS and 78.3% were benign. Sensitivity of the ACR-TIRADs and ATA respectively was to detect non-benign nodules was 70% and 97% Specificity was 29% and 11%. Positive predictive value was 18% and 9% whereas Negative predictive value was 81% and 98%. 28% of the FNAs done in 2015 could have been avoiding if applying the TIRADs criteria, however 15 non-benign and 8 malignant cases would have been missed.Conclusion: The TIRADs approach adds value to the system by reducing many unnecessary biopsies but clinicians need to use their own judgement as some non-benign cases will be missed.