MODIFIED THYROID IMAGING REPORTING AND DATA SYSTEM OF THYROID NODULES WITH SUSPICIOUS SONOGRAPHIC CRITERIA: PREDICTION OF MALIGNANCY FOR CLINICAL MANAGEMENT.

Objective: To validate the effectiveness of the TIRADS classification in assessment of thyroid nodules with suspicious sonographic criteria and its application in clinical practice. Materials and Methods: 1266 nodules with suspicious sonographic signs in 750 patients were included in our study. US scans of the thyroid gland and neck regions were performed. Color Doppler and elastography were done for all nodules. Each nodule was analysed according to the size, shape, margin, internal component (solid or mixed), evidence of calcifications, degree of hypoechogenicity, vascularity and stiffness on elastography. Each criterion was assigned a point, and an ad-ditional point was added for suspicious cervical lymph nodes. A final score of malignant probability was obtained. US-guided FNAB was performed for each nodule with a 21-gauge needle. Results: The study included 429 patients with 821 malignant nodules (57.2%) and 321 patients with 445 benign nodules (42.8%). Suspicious sonographic features; including marked hypoechogenicity, irregularity and ill definition of the margins, microcalcification/non-calcification, taller than wider and hard nodules were associated with significant increase in the rate of the pathologically proven malignancy. The US features of each thyroid nodule were characterized and classified into different TIRADS categories which were confronted with the results of pathology. The risk of malignancy was found to increase from TIRADS 4a to 5. No single US criteria is fully predictive of malignancy. Conclusion: TIRADS is more accurate in assessing thyroid nodules by using numbers of US features and not depending on each criterion separately. Based on the score assigned and the risk of malignancy of each in category 4aFNAC should be limited to patients having other risk factors of developing malignancy. Higher categories including 4b and 4c must proceed to FNAC except if contra-indicated. Category 5 should undergo surgery.