Ultrasound-guided fine needle aspiration biopsy (FNAB) on thyroid nodules : correlation with sonographic findings

Purpose: To analyze the results of ultrasound-guided fine needle aspiration biopsy (FNAB) on thyroid nodules with sonographic correlation, especially for the case of insufficient or suspicious cytology results.Methods and Materials: Total 1056 thyroid nodules of 1007 patients underwent ultrasound (US) with fine needle aspiration biopsy by one experienced radiologist in our hospital for 13 months.Diagnostic categories (benign, probably benign or suspicious) based on US findings and sonographic characterization (cyst, mixed or solid) of each nodule was prospectively evaluated.The cytology results were divided into four groups: benign, suspicious (follicular or Hurthle cell neoplasm and suspicious papillary carcinoma), malignant, and insufficient.Results: In regard to US findings, there were 45 benign (4.3%), 765 probably benign (72.4%) and 246 suspicious (23.3%) nodules out of 1056 thyroid nodules.In sonographic characterization, 45 (4.3%) nodules were cyst, 410 (38.8%) nodules were mixed and 601 (56.9%) nodules were solid.In cytology results, 646 nodules were benign, 159 were malignant, 106 were suspicious and 145 were insufficient.Three hundred three nodules were underwent operation and in pathology results, there were 115 benign nodules and 188 malignant nodules.Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) and accuracy of our sonographic categories were 86.2-87.3%,85.2-93.8%,80.5-90.5%,79.0-96.1% and 85.8-92.3%respectively.Sensitivity, specificity, PPV, NPV and accuracy of our FNAB cytology results were 76.8-97.3%,66.7-99.0%,84.5-99.3%,69.5-93.0%and 84.5-97.2%.There were no significant differences in insufficient rates between nodules less than 1cm and more than 1cm.Among the insufficient (n=145) or suspicious (n=106) cytology results, diagnostic categories were significantly correlated with pathology results.Conclusion: Ultrasound-guided FNAB can provide high sensitivity, specificity and iv diagnostic accuracy in patients with thyroid nodules, even in small (less than 1cm) nodules.And sonographic findings are very useful in cases of insufficient or suspicious cytology results.