Fine needle aspiration cytology, or FNA for short, applied in diagnosing thyroid nodules is considered the most effective method due to its accuracy of over 95%; with a positive predictive value of 89-98%, a negative predictive value of 94-99%; and false negative and false positive rates of less than 1%. FNA has helped select the right cases requiring surgery, reducing the number of cases requiring surgery by more than half, which means reducing treatment costs.