Ultrasonography-Based Classification and Reporting System for the Malignant Risk of Thyroid Nodules

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Objective: The aim of this study was to test the predictive value of a Thyroid Imaging Reporting and Data System (TI-RADS) for malignant thyroid nodules. Methods: Ultrasonographic data was examined for 910 thyroid nodules with histopathologically confirmed diagnoses. Nodules were placed into incomplete (category 0) or complete final categories (1, 2, 3a, 3b, 3c, 4, or 5) based on the presence and number of ultrasonographic features of malignancy, and the predictive value for the malignancy of nodules in categories 2-4 was assessed. Results: The overall rate of malignancy among thyroid nodules included in the study was 59.34%. The rate of malignancy gradually increased according to TI-RADS categories as follows: category 2, 5.4%; category 3 (a-c), 36% to 92%; and category 4, 99.0%. When nodules of category 2 were counted as benign, the reliability of the TI-RADS classification for determining the risk of malignancy was as follows; sensitivity, 98.15%; specificity, 47.84%; positive predictive value, 73.31%; negative predictive value, 94.65%; and odds ratio, 48.61. Conclusions: The TI-RADS classification used in this study is relatively simple and provides a reliable measure of the risk of malignancy of thyroid nodules.