Role of 18 F-FDG PET/CT in Head and Neck Squamous Cell Carcinoma: Current Evidence and Innovative Applications.

Simple Summary: Among head–neck tumors, squamous cell carcinoma is the most frequent histotype and includes a range of malignancies with different sites of origin as well as different therapeutic strategies and clinical outcomes. In daily practice, patients with head–neck squamous cell carcinoma are seen in various clinical settings, requiring a multidisciplinary approach to therapeutic decisions and clinical care. 18F-FDG PET/CT plays a well-defined role in the management of these tumors for pre-treatment staging and radiotherapy planning as well as treatment-response assessment and post-therapy follow-up. This paper is an overview of the standard use of 18F-FDG PET/CT in the various clinical scenarios of head–neck squamous cell carcinoma. Also, emerging applications will be reviewed, including the use of radiopharmaceuticals other than 18F-FDG, PET/MRI implementation in clinical practice, and the use of radiomics and machine learning. This article provides an overview of the use of 18F-FDG PET/CT in various clinical scenarios of head–neck squamous cell carcinoma, ranging from initial staging to treatment-response assessment, and post-therapy follow-up, with a focus on the current evidence, debated issues, and innovative applications. Methodological aspects and the most frequent pitfalls in head–neck imaging interpretation are described. In the initial work-up, 18F-FDG PET/CT is recommended in patients with metastatic cervical lymphadenectomy and occult primary tumor; moreover, it is a well-established imaging tool for detecting cervical nodal involvement, distant metastases, and synchronous primary tumors. Various 18F-FDG pre-treatment parameters show prognostic value in terms of disease progression and overall survival. In this scenario, an emerging role is played by radiomics and machine learning. For radiation-treatment planning, 18F-FDG PET/CT provides an accurate delineation of target volumes and treatment adaptation. Due to its high negative predictive value, 18F-FDG PET/CT, performed at least 12 weeks after the completion of chemoradiotherapy, can prevent unnecessary neck dissections. In addition to radiomics and machine learning, emerging applications include PET/MRI, which combines the high soft-tissue contrast of MRI with the metabolic information of PET, and the use of PET radiopharmaceuticals other than 18F-FDG, which can answer specific clinical needs. [ABSTRACT FROM AUTHOR]