Early detection of viable residual tumor or early neoplastic recurrence represents a real challenge in monitoring patients treated with concomitant chemoradiotherapy squamous cell carcinoma of the upper aerodigestive tract.

The locoregional recurrence rate is indeed high (up 40%) over the first two years of this therapeutic method.

The conventional imaging methods such as CT and MRI appear limited in terms of sensitivity because of the many post-treatment changes are fibrosis, tissue edema and the tissue distortion.

PET-CT 18F-FDG proves to be a non-invasive, reliable for the detection of residual tumor and metastasis, even in the absence of clinical signs.

To date, the acquired CT examination in the same time and in the same position that PET is performed without iodinated contrast injection, used for anatomical identification and attenuation correction of PET fused images. The patient usually has a second CT imaging, centered on the neck with contrast injection iodized within the radiology department.

To date, no team has yet studied the interest of the PET-CT 18F-FDG coupled with a CT scan with contrast injection iodized in the diagnosis of early recurrence in head and neck malignancies while interest of the contrast agent injection has been demonstrated in ovarian neoplastic recurrence research, pancreatic and colon.

Inclusion Criteria:

• Patients aged over 18 years
• Squamous cell carcinoma of head and neck
• neoplastic Location: oropharynx, oral cavity, hypopharynx, larynx
• New Patients treated with concomitant radiochemotherapy
• Treatment with chemoradiotherapy ended 3 months ago
• Affiliation to a social security scheme
• Patient who provided written informed consent

Exclusion Criteria:

• During Pregnancy or absence of effective contraception in reproductive years
• Breastfeeding
• Creation of a cervical CT with injection of iodinated contrast, in the therapeutic monitoring, dated less than 14 days
• Other history of malignancy, including head and neck carcinomas previously treated outside the basal cell cancer or cervical cancer, treated and cured
• uncontrolled Infectious diseases
• Allergy to iodine
• Severe renal impairment (renal clearance <30ml / min according to Cockcroft)
• No consent
• Patient deprived of liberty, under guardianship
• Any medical or psychological condition associated that might compromise the patient's ability to participate in the study
• Failure to submit to medical monitoring study for geographical, social or psychic