Agreement between thyroid nodules ultrasound and cytology of fine needle aspiration (FNA) based on TIRADS and Bethesda system

Thyroid nodules are common among the general population and they increase the risk of thyroid malignancies. This study was done to evaluate the correlation of findings of ultrasound based on Thyroid Imaging and Reporting Data System (TIRADS) and cytology of fine needle aspiration (FNA) based on Bethesda system to evaluate of thyroid nodules.

This descriptive-analytical study, was performed on 165 patients (152 females and 13 males) referred to the sonography center of Sayyad Shirazi Educational Hospital, Gorgan, northern Iran during 2018. Ultralosonographic features of nodules were recorded in the pre-filled checklist. According to TIRADS and endocrinologist clinical suspicion, couple of patients was eligible for FNA under the ultrasound guidance. The cytology of FNAs was reported based on the Bethesda system classification.

The mean age was significantly lower in patients with malignant nodules (35.4 vs 44.8; P<0.05). Frequency of malignancy was 8 times higher among females than males (16 vs. 2). TIRADS 3 and 4 were the most common categories among the others with the prevalence of 44.4% and 32.3%, respectively. Bethesda 2 and 4 were the most prevalent categories with prevalence of 58.8% and 20.6%, respectively. The strongest agreement was observed between TIRADS 2 and Bethesda 2 that showed benign findings. Kappa index was 0.061 between TIRADS and Bethesda (P<0.05). Echogenicity, echogenic foci, shape, and margin of nodules were seen significantly more in malignancy.

The most accurate prediction of TIRADS belongs to benign nodules. The correlation between TIRADS and Bethesda was evaluated to be significant overall and the maximum level of correlation was at benign findings. Therefore, these two systems can efficiently be used in order to rule out malignancies and reduce the rate of invasive interventions.