Inclusion Criteria:

- Patient is >18 years and male or female of any race / ethnicity.

- Patient or patient's legally acceptable representative provides written inform
consent Patient is willing and able to comply with protocol procedures.

- Patient has newly diagnosed histologically confirmed squamous cell carcinoma of the
head and/or neck whose primary origin is from the oral cavity, oropharynx,
hypopharynx, larynx or nasopharynx.

- Patient is scheduled to have or already has had a clinical [F-18]FDG PET/CT scan
prior (recommended to be within 14 days prior) to the [F-18]HX4 PET/CT scan.

- Patient has a primary tumor ≥ 2.0 cm in longest axis measured by CT or MR; or lymph
node ≥ 2.0 cm in shortest axis measured by CT or MR if primary tumor < 2 cm on CT or
MR; CT may be part of required [F-18]FDG PET/CT scan or a separate pre-surgery CT
scan.

- Patient is scheduled to undergo complete tumor resection within 7 days for his/her
cancer care after the [F-18]HX4 PET/CT scan is performed.

- Patient has not had nor will have neoadjuvant treatment, including radiation and
chemotherapy, prior to patient's planned tumor resection.

Exclusion Criteria:

- Female patient is pregnant or nursing.

- Patient is not capable of remaining still for duration of imaging procedure (~ 4
hours).

- Patient has undergone an investigative, radioactive research procedure within 7
days prior to study participation, or is scheduled to undergo such a procedure during
the study participation period.

- Patient has chronic renal function failure or is on renal dialysis

- Patient has any other condition or personal circumstance that, in the judgment of
the investigator, might interfere with the collection of complete data.