Correlation between Ultrasound-based TIRADS and Bethesda System for Reporting Thyroid-cytopathology: 2-year...

In recent times, high-resolution ultrasound thyroid imaging has paved the way for significant transformation in clinical approach to thyroid nodule. There are several risk stratification systems in thyroid imaging, developed with an aim, not only to reduce the inter-observer variability but also to establish effective communication system. Thyroid image reporting and data system (TIRADS) classification system, which is similar to breast imaging reporting and data system for breast lesion, is the most useful of all. To our knowledge, there is just a handful published research articles available based on Indian population in this regard. In this article, we study the thyroid nodules using high-resolution ultrasound in Indian population and we try to correlate the TIRADS and Bethesda system for reporting thyroid cytopathology.

This prospective study includes 184 patients studied over a period of 2 years (April 2015-April 2017). Patients having thyroid nodule in B-mode ultrasound and are scheduled to get a fine-needle aspiration cytology (FNAC) done. Bethesda classification of these nodules is tabulated in follow-up period simultaneously. By comparing these data, efficacy of TIRADS in differentiating benign from malignant nodules are assessed finally using accuracy, positive predictive value (PPV), cross-tabulation, and Chi-square tests.

Out of the 117 TIRADS 2 nodules, none turned out to be Bethesda IV or higher, which means none of these nodules turned out to be malignant. The risk of malignancy for TIRADS 2, TIRADS 3, TIRADS 4, and TIRADS 5 was 0, 2.2, 38.5, and 77.8%, respectively. The risk of malignancy percentage in our study is similar to those values obtained in other prominent studies.

The probability of a particular nodule being malignant can be effectively inferred from the ultrasound-based TIRADS system with a certain level of confidence. Considering our results and other literature reviews, it be can be safely assumed that FNAC can be at least deferred in patients having TIRADS 2 nodules, which contribute to majority of newly detected cases. In our experience, there is a remarkable correlation exists between TIRADS ultrasound classification and Bethesda cytology, especially for benign nodules.