Differentiated thyroid cancer and positron emission computed tomography: when, how and why?

Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) has become an indispensable tool in oncology, offering both metabolic and anatomical insights into tumor behavior. Most differentiated thyroid carcinomas (DTC) are indolent and therefore FDG PET/CT is not routinely incorporated into management. However, in biologically aggressive DTCs, FDG PET/CT plays a crucial role in detecting recurrence and metastases.

This narrative review with articles from the last 25 years from PubMed database, explores the evolving role of FDG PET/CT, focusing on its utility in recurrence detection, staging, and follow-up of radioactive iodine (RAI)-refractory cases. Current guidelines recommend FDG PET/CT primarily for high-risk patients with elevated thyroglobulin levels and negative RAI scans (TENIS syndrome). We also examine advancements in PET imaging, novel radiotracers and theragnostic approaches that enhance diagnostic accuracy and treatment monitoring.

While FDG PET/CT has proven valuable in biologically aggressive DTC, its routine use remains limited by cost, accessibility, and concerns regarding radiation exposure in younger patients requiring repeated imaging studies. Future developments in molecular imaging, including novel tracers and artificial intelligence-driven analysis, are expected to refine its role, leading to more personalized and effective management, though economic and reimbursement challenges remain important considerations for broader adoption.