Positron Emission Tomography and Molecular Imaging of Head and Neck Malignancies

Abstract

Metabolic reprogramming and avid fluorodeoxyglucose (FDG) uptake in locally advanced head and neck squamous cell carcinomas and other cancers of the upper aerodigestive tract lead to favorable sensitivity and diagnostic accuracy of FDG PET/CT or PET/MR compared to conventional imaging. Meanwhile, the role of non-FDG PET in head and neck malignancies is rapidly expanding. Accurate staging, identifying a clinically occult primary, or detection of distant metastasis or a synchronous malignancy on FDG PET significantly impacts management. FDG uptake after definitive therapy is an invaluable biomarker for surveillance. Patients with metabolic resolution can be spared from neck dissection, whereas FDG avid refractory disease or distant metastasis could necessitate surgical or systemic therapy. PET tracers targeting amino acid transport or fibroblast activation hold promise for improved specificity and better delineation of tumor prior to radiation therapy given their low physiologic or inflammatory uptake in head and neck compared to FDG. Tracers for hypoxia or cellular proliferation provide complementary information to FDG after radiation therapy for assessment of residual malignant cells that could lead to treatment failure. FDG remains the primary tracer for imaging lymphoma and other pediatric head and neck malignancies. Several other PET tracers such as gallium-68-labeled somatostatin receptor analogs and fluorodopa are being increasingly used for detection and characterization of head and neck paragangliomas and certain other cancers. FDG and other PET radiopharmaceuticals are increasingly being exploited in guiding clinical management of various head and neck malignancies and significantly impact patient outcomes.