Abstract
Follicular cell-derived thyroid carcinomas constitute the majority of thyroid malignancies. This heterogeneous group of tumours includes well differentiated, poorly differentiated, and undifferentiated forms, which have distinct pathological features, clinical behaviour, and prognosis. Positron emission tomography with 2-[(18)F]fluoro-2-deoxy-D-glucose combined with computed tomography ([(18)F]FDG PET/CT) is an imaging modality used in routine clinical practice for oncological patients. [(18)F]FDG PET/CT has emerged as a valuable tool for identifying patients at high risk of poor clinical outcomes and for facilitating individualized clinical decision-making. The aim of this comprehensive review is to summarize current knowledge regarding the role of [(18)F]FDG PET/CT in primary diagnosis, treatment, and follow-up of follicular cell-derived thyroid carcinomas considering the degree of differentiation. Controversial issues, including significance of accidentally detected [(18)F]FDG uptake in the thyroid, the role of [(18)F]FDG PET/CT in the early assessment of response to molecular targeted therapies, and its prognostic value are discussed in detail.