Evaluating thyroid nodules: predicting and selecting malignant nodules for fine-needle aspiration (FNA) cytology

OBJECTIVE: To form and assess a set of diagnostic ultrasound criteria to select malignant nodules for fine-needle aspiration (FNA) cytology and reduce number of FNA biopsies. METHODS: In this prospective observational service evaluation study, 171 thyroid nodules that underwent FNA cytology were independently scored by two observers for established nodular sonographic characteristics for malignancy. The final diagnosis was confirmed by surgery or a 6-month follow-up in nodules with benign cytology. RESULTS: Logistic regression analysis and receiver operating characteristic curve analysis results indicate good and comparable predictive powers of certain ultrasound characteristics in predicting malignancy. The highest sensitivity in detecting malignancy was achieved when taking together the information of marked hypoechogenicity, microcalcification and mixed central/peripheral or central Doppler colour flow pattern. A sensitivity of 100 % and a specificity of 76 % were obtained in detecting malignant nodules using this criteria. CONCLUSIONS: Our study proposes a set of ultrasound and colour Doppler criteria to safely select malignant thyroid nodules for FNA cytology. MAIN MESSAGES: • There is a need to safely select malignant nodules for FNA cytology and reduce unnecessary FNA • Some ultrasound features are specific but none are independently/fully predictive of malignancy • We have prospectively tested a set of ultrasound criteria for selecting nodules for FNA cytology • Our ultrasound criteria detected malignant nodules with a 100 % sensitivity and 76 % specificity • A high sensitivity is clinically desirable as it selects many, if not all, malignant nodules for FNA