Purpose: Discrepancies between the uptakes of (18)F-fluorodeoxyglucose ((18)F-FDG) and (131)I in papillary thyroid carcinoma have been reported. We compared 18F-FDG uptake with the expressions of glucose transporter type 1 (GLUT1) and sodium-iodide symporter (NIS) in untreated papillary thyroid carcinoma.
Materials and methods: A total of 33 consecutive patients (male:female = 12:21; mean age, 46.6 ± 13.0 years) with initially diagnosed papillary thyroid carcinoma were prospectively included in the study. All subjects underwent preoperative (18)F-FDG positron emission tomography/computerized tomography scans followed by surgery. The expressions of GLUT1 and NIS were evaluated in resected primary tumors and metastatic lymph nodes by immunohistochemical staining and were compared with the maximum standard uptake value of each lesion, respectively.
Results: None of the 40 primary tumors showed significant expressions of GLUT1. Significant expressions of NIS were found in 14 primary tumors (35.0%). Among 36 metastatic lymph nodes, only 1 showed GLUT1 expression. Significant expression of NIS was found in 13 (36.1%) metastatic nodes. The maximum standard uptake value of both primary tumors and metastatic nodes with negative expression of NIS was significantly higher than those with a positive expression of NIS (10.6 ± 10.8 vs. 4.9 ± 5.2, p = 0.011).
Conclusions: The 18F-FDG uptake of untreated papillary thyroid carcinoma has an inverse correlation with NIS expression. However, GLUT1 expression does not appear to be associated with 18F-FDG uptake in untreated papillary thyroid carcinoma.