Association Between ¹⁸F-FDG Avidity and the BRAF Mutation in Papillary Thyroid Carcinoma

다국어 초록 (Multilingual Abstract)

Purpose The BRAF mutation, a potential prognostic factor in papillary thyroid carcinoma (PTC), is associated with a high expression of the glucose transporter gene. We investigated which clinicopathologic factors, including BRAF mutation status, influence $^{18}F$-fluoro-2-deoxyglucose> ($^{18}F$-FDG) avidity. Methods We retrospectively reviewed 55 patients who underwent BRAF analysis from biopsy-confirmed PTC and $^{18}F$-FDG positron emission tomography/computed tomography within 6 months before undergoing thyroid surgery from September 2008 to August 2014. Tumors were considered to be $^{18}F$-FDG avid if the uptake was greater than that of the liver. $^{18}F$-FDG uptake of PTCs was also analyzed semiquantitatively using $SUV_{max}$. The association between $^{18}F$-FDG avidity and clinicopathologic variables (age, tumor size, perithyroidal extension, cervical lymph node status, and BRAF mutation status) was investigated. Results Twenty-nine (52.7 %) of 55 patients had $^{18}F$-FDG-avid PTCs. PTCs with the BRAF mutation showed higher $^{18}F$-FDG avidity (24/38, 63.2 %) than those without (5/17, 29.4 %). The BRAF mutation (p=0.025) and tumor size (p=0.003) were significantly associated with $^{18}F$-FDG avidity in univariate analysis, and the BRAF mutation status remained significant after adjusting for tumor size in multivariate analysis (p=0.015). In the subgroup of tumor $size{\geq}1cm$, the BRAF mutation was the only factor significantly associated with $^{18}F$-FDG avidity (p=0.021). The mean $SUV_{max}$ of PTCs with the BRAF mutation was significantly higher than that of those without ($4.89{\pm}6.12$ vs. $1.96{\pm}1.10$, p=0.039). Conclusions The BRAF mutation must be one of the most important factors influencing $^{18}F$-FDG avidity in PTCs, especially in those with a tumor $size{\geq}1cm$.