Thyroid imaging reporting and data system score combined with B ethesda system for malignancy risk stratification in thyroid nodules with indeterminate results on cytology

Summary Context The thyroid imaging reporting and data system ( TI ‐ RADS ) was designed to better select patients who had undergone fine‐needle aspiration biopsies ( FNAB s) with high sensitivity and accuracy. However, the combination of TI ‐ RADS scores and B ethesda system categories in indeterminate thyroid nodules has not been examined extensively. Objective This study aimed to stratify indeterminate thyroid nodules ( B ethesda categories III , IV and V ) according to risk of malignancy as determined by combining TI ‐ RADS score with B ethesda system classification. Design Retrospective study. Histopathological, cytological and ultrasound ( US ) data were available for 242 cases after surgery, including 136 indeterminate nodules. Methods All thyroid cytopathological slides and US reports were reviewed and classified according to B ethesda system and TI ‐ RADS categories. The malignancy rate was determined for each B ethesda category, TI ‐ RADS score and both methods combined of indeterminate nodules. Results The malignancy rates were 8·7%, 51·3% and 67·5% for B ethesda categories III , IV and V, respectively. Based on histopathological comparison, the accuracy was 66·7% for TI ‐ RADS greyscale. TI ‐ RADS 3 and 4A scores were observed in 80% of B ethesda III cases, which led to 80% sensitivity and 90% of negative predictive value ( NPV ). In contrast, for nodules scored as TI ‐ RADS 4B and 5, the combined cytological results of B ethesda IV and V resulted in a higher risk of malignancy (75% and 76·9%, respectively, P  <   0·001). Conclusions In view of the high NPV of TI ‐ RADS 3/4A only in B ethesda III category, a surgical approach could be considered for lesions defined as B ethesda III , IV and V when TI ‐ RADS 4B and 5 were concomitant.