Positive rate and accuracy of ultrasound-guided fine-needle aspiration cytology for detecting suspected thyroid carcinoma nodules of different sizes

Abstract

To analyze the accuracy and positive rate of ultrasound-guided fine-needle aspiration (US-FNA) cytology for detecting suspected thyroid cancer nodules of different sizes. A total of 591 patients with 594 suspected malignant thyroid nodules received examinations with US-FNA cytology. Based on their size, the nodules were divided into group I (4-5 mm), group II (6-10 mm), group III (>10 mm). With the results of pathology as the standard, we analyzed the results of US-FNA cytology for detecting thyroid carcinoma in terms of its accuracy, indeterminate rate, positive predictive value and negative predictive value for nodules of different sizes. The positive rates in group I, group II and group III were 39.2% (40/102), 48.2% (172/357) and 65.2% (88/135), respectively, similar between groups I and II (P=0.107) and differed significantly between groups I and III (P=0.000) and between groups II and III (P=0.001). The accuracy, indeterminate rate, positive predictive value and negative predictive value in the 3 groups were 95.5% (21/22), 97.1% (100/103), and 94.4% (51/54); 2.9% (3/102), 2.8% (10/357), and 1.5% (2/135); 100%, 100%, and 98%; 66.7%, 57.1%, and 33.3%, respectively, showing no significant differences among the 3 groups. The size of the thyroid nodules can affect the positive rate but does not have significant effects on the accuracy, indeterminate rate, positive predictive value or negative predictive value of US-FNA cytology.