Ultrasound-Guided Fine-Needle Aspiration Biopsy Of Thyroid Nodules Smaller Than 10 mm in the Maximum Diameter: The Efficacy and Its Correlation with TIRADS Classification.

Objective: This retrospective study evaluated the effectiveness of ultrasound-guided fine-needle aspiration cytology (US-FNAc) for diagnosing thyroid nodules less than 10mm and explored the correlation between the TIRADS classification and US-FNAc reports.

Methods: This analysis of 344 patients with 407 thyroid nodules less than 10mm was conducted from June 2022 to July 2023 at the Centre of Endocrinology and Diabetes, Danang Family hospital, Danang, Vietnam. US-FNAc was performed on all nodules, and cytology was reported according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of US-FNAc were calculated. Correlation between cytology and TIRADS classification was assessed using Spearman's correlation.

Results: Adequate specimens were obtained in 81% of thyroid nodules after the first FNAc. Cytological diagnoses included 36.6% benign, 12.8% suspicious for malignancy, 1.2% malignant, and 19.7% indeterminate. Among surgically resected thyroid nodules, 78.6% were malignant. US-FNAc demonstrated moderate sensitivity (80%) and high PPV (92.3%) but lower specificity (75%) and NPV (50%) for malignancy in nodules less than 10mm in max diameter. A significant positive correlation (r = 0.24, p < 0.001) was observed between TIRADS classification and TBSRTC.

Conclusion: US-FNAc offers moderate sensitivity and high PPV for diagnosing malignancy in smaller than 10 mm thyroid nodules, but specificity and NPV are lower. A positive correlation exists between TIRADS classification and cytological outcomes.