This trial studies how well standard and delayed fludeoxyglucose F-18 (FDG)-positron emission tomography (PET)/computed tomography (CT) given after standard radiation and chemotherapy works in assessing patients with head and neck squamous cell cancer that has spread to other places in the body. Diagnostic procedures, such as PET/CT, use radioactive material, such as fludeoxyglucose F-18, to find and diagnose head and neck tumors and may help to find out how far the disease has spread.

PRIMARY OBJECTIVE:

I. To assess the optimal imaging time using FDG positron emission tomography (PET) with comparison between a standard of care 1-hour scan (early) and the research scan of 3-hours scan (delayed) post radiotracer administration that maximizes separation of activity between lesion and non-lesional parenchyma (measured as lesion/background [L/B] ratio) in patients with head and neck primary squamous cell carcinoma following chemoradiation treatment.

OUTLINE:

Patients receive fludeoxyglucose F-18 intravenously (IV) over 1 minute and undergo PET/CT at 70 and 180 minutes after injection at 12-14 weeks following standard chemoradiation (CRT) completion.

After completion of study, patients are followed up at 30 days and then periodically for up to 6 months.

Inclusion Criteria:

• Adult with computed tomography (CT) or fludeoxyglucose F-18 (FDG) positron emission tomography (PET) findings of cervical nodal metastasis from a head and neck primary squamous cell carcinoma treated with definitive chemoradiation

Exclusion Criteria:

• Children
• No evidence of cervical nodal metastasis
• Active infection of the head and neck
• Known allergy to FDG, iodine or gadolinium-based contrast agents
• Blood glucose (> 250 mg/dl)
• Pregnant women