Objective: To assess the accuracy of ultrasonography and cytology in predicting malignancy in thyroid nodules.
Design: Prospective open study.
Setting: Thyroid centre, Japan.
Subjects: 329 nodules in 309 patients examined by a new ultrasound scanner and ultrasound-guided fine-needle aspiration biopsy.
Interventions: Comparison of ultrasonographic, cytological, and combined diagnosis with the histological diagnosis.
Main outcome measures: Sensitivity, specificity, and accuracy of each diagnostic method.
Results: The sensitivity, specificity, accuracy were 84%, 87%, 85% for cytological diagnosis, and 82%, 91%, and 87% for ultrasonographic diagnosis. By using ultrasonographic diagnosis when cytological specimens were inadequate or gave false negative results, the sensitivity, specificity, and accuracy went up to 89%, 91%, and 90%, respectively. We could not diagnose follicular carcinomas accurately by combined cytology and ultrasonography.
Conclusion: The combination of ultrasonography and cytology improves the accuracy of diagnosis of thyroid nodules, but is less effective with follicular tumours.