Diagnostic validity of ultrasonography in thyroid nodules

Objective: To determine the diagnostic validity of thyroid ultrasound in differentiating between benign and malignant thyroid nodules. Methods: The cross-sectional study was conducted at Aga Khan University Hospital, Karachi, from August 2011 to January 2013, and comprised all patients of either gender with thyroid nodules referred for ultrasound thyroid and fine needle aspiration cytology. Ultrasonography was performed by radiologists and ultrasound parameters were assessed and compared with cytology results in all nodules. Diagnostic validity of each ultrasound feature was calculated. Results: Of the 101 patients, 81(80%) were female. The overall mean age was 43±13 years (range: 15-73 years). On histocytopathology, 96(95%) nodules were benign and 5(4.9%) were malignant. The sensitivity and specificity of ultrasound features in predicting malignancy were calcification 80% and 68%; hypoechogenecity 80% and 52%; ill-defined lobulated margin 40% and 96%; solid 80% and 40%; taller than wider 50% and 63%. Each ultrasound feature had negative predictive value ranging from 95% to 98% in malignant nodules. Conclusion: Identification of calcification, hypoechogenecity and solid with ill-defined margins in a thyroid nodule on ultrasound was helpful in suspecting thyroid malignancy and warranted urgent diagnostic fine needle aspiration cytology.