Association between TI-RADS ultrasound categories and BETHESDA cytology categories of thyroid lesions

Ultrasound and cytology are the two major diagnostic modalities employed for the preoperative evaluation of thyroid lesions. Ultrasound thyroid imaging reporting and data systems (TI-RADS) have been proposed for risk stratification of thyroid nodules. The Bethesda system for reporting thyroid cytopathology (TBSRTC) by using six diagnostic categories with a stratified risk of malignancy (ROM) in each category is employed for unambiguous cytology reporting of thyroid lesions. Our objective is to study the association between TI-RADS ultrasound categories and Bethesda cytology categories in thyroid lesions and to find their diagnostic accuracy as compared with histopathological diagnosis wherever possible.

This is a prospective observational study in which a total of 107 patients were studied. Thyroid ultrasound was scored according to TI-RADS classification. A pathologist screened ultrasound-guided FNAC smear, and reporting was done using the Bethesda system of reporting. The pathologist was blinded for the TI-RADS report.

Among all the 107 cases, the patients' age ranged from 8 to 70 years with a mean age of 41.67 ± 14.41 years. The men: women ratio was 1:5. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TI-RADS were 50%, 95.24%, 88.89%, and 71.43%, respectively, with a diagnostic accuracy of 75.68%, while the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of Bethesda were 81.25%, 85.71%, 81. 25%, and 85.71%, respectively, as compared with the histopathological diagnosis. TI-RADS ultrasound categories and Bethesda cytology categories were correlated in 88% of cases.

TI-RADS and TBSRTC classification systems are specific diagnostic modalities in thyroid lesions. They are correlated in the majority of cases.