Clinical Value of Visually Identifiable 18F-fluorodeoxyglucose Uptake in Primary Papillary Thyroid Microcarcinoma

Abstract

Objective This study evaluates the relationship between visually identifiable 18F-fluorodeoxyglucose (FDG) uptake in primary papillary thyroid microcarcinoma (PTMC) and tumor aggressiveness. Study Design Historical cohort study. Setting Tertiary care center. Methods Clinicopathological factors and PET/CT findings of 219 PTMC surgical patients who underwent preoperative 18F-FDG positron emission tomography/computed tomography (PET/CT) were retrospectively reviewed. Results 18F-FDG uptake was observed in the tumors of 124 (56.6%) patients. Tumor size (odds ratio [OR] = 1.774; 95% confidence interval [CI], 1.416-2.223; P < .0001) and Hashimoto thyroiditis (OR = 2.815; CI, 1.237-6.404; P = .014) independently predicted 18F-FDG uptake. Tumor size (OR = 1.495; CI, 1.217-1.835; P < .0001) and BRAFV600E mutation (OR = 3.320; CI, 1.056-10.432; P = .040) independently predicted extrathyroidal invasion. Multiplicity (OR = 2.375; CI, 1.278-4.415; P = .006) independently predicted central lymph node metastasis. Conclusion 18F-FDG uptake in PTMC depends on tumor size and Hashimoto thyroiditis. Therefore, preoperative PET/CT for PTMC may not help in evaluating tumor aggressiveness.