Inclusion Criteria:

- Patient may be male or female and of any race / ethnicity

- Patient is > 18 years old at the time of investigational product administration

- Patient or patient's legally acceptable representative provides written informed
consent

- Patient is capable of complying with study procedures

- Patient is capable of communicating with study personnel

- Patient must have histologically confirmed stage III, or IV squamous cell carcinoma
of the head and neck whose primary origin was from the oral cavity, oropharynx,
hypopharynx, or larynx.

- According to the Karnofsky Performance Status Scale, the patient has a value of ≥
60% at time of screening

- Patient must have normal organ and renal function as defined:

- total bilirubin within normal institutional limits

- AST(SGOT)/ALT(SGPT) less than or equal to 2.5 x institutional upper limits of
normal

- creatinine within normal institutional limits

- BUN within normal institutional limits

- PT and PTT < 2.0 x institutional upper limits of normal

Exclusion Criteria:

- Patient is younger than 18 years old at the time of investigational product
administration

- Female patient is pregnant or has a positive serum pregnancy test

- Patient is unable to remain still for duration of imaging procedure

- Patient has a history of significant renal disease

- Patient has previously received [F-18]HX4 at any time, or any other investigational
product in the past thirty days.

- Patient has been involved in an investigative, radioactive research procedure within
the past year

- Inadequate tumor sites or volume to allow for biopsy

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