US, colour-Doppler US and fine-needle aspiration biopsy in the diagnosis of thyroid nodules

PURPOSE: The purpose of this study was to correlate the diagnosis of benign or malignant thyroid nodules obtained with grey-scale ultrasound (US) and colour-Doppler US with the cytological findings after US-guided fine-needle aspiration (FNA). MATERIALS AND METHODS: Between January 2004 and June 2005, 516 thyroid nodules in 420 patients (181 solitary thyroid nodules and 239 multiple nodules) were prospectively evaluated with US, colour-Doppler US and US-guided FNA. The nodules were classified as sonographically benign, suspicious or malignant in accordance with established US criteria. Cytological findings were classified as inadequate, benign, indeterminate, suspicious or malignant. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of US and colour-Doppler US were evaluated using FNA as the reference procedure. RESULTS: The sensitivity, specificity, PPV, NPV and overall accuracy values of grey-scale US were 46%, 73%, 34%, 82% and 67%, respectively, for solitary thyroid nodules and 35%, 72%, 14%, 90% and 68%, respectively, for multiple nodules. The evaluation of nodule vascularity with colour-Doppler US produced a slight increase in sensitivity but a slight reduction in specificity. CONCLUSIONS: Thyroid nodules cannot be accurately characterised using grey-scale US or colour-Doppler US.