Department of Radiology, Masan Samsung Hospital, Sungkyunkwan University School of Medicine, Korea. rmh96@samsung.co.kr
Published online: December 1, 2004.
ABSTRACT
PURPOSE: To evaluate the ultrasonographic findings according to the size of the nodule in a papillary carcinoma of the thyroid(PTC). MATERIALS AND METHODS: During a three-year period, 83 patients with a histologically proven PTC were included. All the nodules were classified into small nodules (SN < or = 1 cm), medium-sized nodules (1 cm < MN < or = 2cm) and large nodules (LrN > 2 cm). The echogenicity, margin, halo sign, calcification, regional lymph node metastasis(RLNM) in gray scale ultrasonography (US) and vascularity in the color doppler US were analyzed retrospectively according to their sizes. The sensitivity of the US was also assessed. RESULTS: Eleven (91.7%) out of 12 SNs, 45 (86.5%) out of 52 MNs and 12 (63.2%) out of 19 LrNs showed low echogenicity, so the echogenicity increased as the size increased (p < 0.05). An ill-defined or irregular margin was observed in 8 (66.7%) of the SNs, 31 (59.6%) of the MNs and 7 (36.8%) of the LrNs, and a lobulated margin was observed in 1 (8.3%) of the SNs, 16 (30.8%) of the MNs and 10 (52.6%) of the LrNs, so the margin became clearer as its size increased but was lobulated. A halo sign was observed in only 10 (12.0%) out of 83 nodules. Microcalcification was observed in 28 (33.7%) out of 83 nodules, but only in 1 (8.3%) out of 12 SNs. RLNM was frequently observer in the MNs (11.5%) and LrNs (15.8%). In color Doppler US, a low and high blood flow were observed in 50% and 16.7% of the SNs, 35.3% and 44.1% of the MNs and 40% and 60% of the LrNs, respectively. Therefore, the blood flow per unit area increased as the size increased. The sensitivity of US was 85.5% in all nodules. CONCLUSION: The echogenicity of PTC increased significantly as the size increased. Although there was no statistical significance, there were differences in the shape of the margin, the degree of vascularity and the frequency of the RLNM according to the size. US is a very sensitive study in diagnosing PTC and its sensitivity will be improved by considering the different ultrasonographic findings depending on the size.