American College of Radiology Thyroid Imaging Reporting and Data System Score has High Diagnostic Value in the Diagnosis of Malignant Thyroid Nodules

Introduction: A palpable thyroid swelling is a very common finding and is seen in almost 12% of Asian Indian population. Thyroid imaging reporting and data system (TI-RADS) can be used as a risk stratification system to determine malignant or benign thyroid nodules and necessity of further intervention. Objective: The objective of this study was to determine the positive predictive value (PPV) of TI-RADS category/ultrasound using TI-RADS categories in the diagnosis of malignancy in clinically suspected thyroid nodule and necessity for further intervention in the case of malignant thyroid nodules. Materials and Methods: We conducted a prospective study evaluating 110 patients (140 thyroid nodules) from March 2018 to April 2020 including patients with thyroid swelling. Ultrasound was performed by a radiologist on the patients, and targeted fine-needle aspiration cytology from thyroid nodules was interpreted by an experienced pathologist. Ultrasound features and TI-RADS category were compared with cytology and surgical histopathology. Sensitivity, specificity, PPV, and positive likelihood ratio in different categories of TI-RADS nodules were calculated. Results: A total of 113 thyroid nodules were assessed. Out of 113 nodules (right lobe - 64, isthmus - 6, and left lobe - 43), 84 nodules were benign and 29 nodules were malignant. Eleven (10%) patients were found to have metastatic cervical lymphadenopathy. There was no significant difference in the occurrence of malignant nodules according to gender, location of the nodule, or size of the nodule. The mean anteroposterior and transverse diameter of benign nodule was 14.1 ± 6.9 mm and 20.9 ± 9.9 mm, respectively, whereas in the case of malignant nodules, it was 15.6 ± 7.1 mm and 19.5 ± 9.0 mm, respectively. A TI-RADS score of ≥4 had 84% PPV for malignancy. The PPV for malignancy was 32.2%, 49.1%, and 100% for TI-RADS 2, 3, and 5 categories. Conclusion: TI-RADS is a simple, practical, and cost-effective tool for assessing the malignancy rates of thyroid nodules. TI-RADS categories 4 and 5 have high PPV for malignancy in thyroid nodules.