This study investigates the diagnostic value of PET/MRI for cervical lymph node metastases from head and neck squamous cell carcinomas.

The Danish fast-track cancer program standardizes the work-up of patients suspected of head and neck cancer. Currently, the guidelines recommend head and neck magnetic resonance imaging (MRI) as the standard imaging modality for assessment of the primary tumor site and potential nodal metastases. However, recent studies have shown advantages in the use of 18F-FDG-PET (PET) combined with computed tomography (CT) due to its superiority in detecting metastases and synchronous cancers.

During the last couple of years PET/MRI has been introduced. MRI is known to provide the highest anatomic detail in the head and neck region, and preliminary studies show promising results. However, the evidence is still very sparse.

The purpose of the project is to investigate the diagnostic value of PET/MRI in patients with head and neck squamous cell carcinoma. The hypothesis is that PET/MRI provides a more precise diagnosis of regional lymph node metastases, and thus, make the surgical treatment of the neck more accurate and less invasive resulting in reduced morbidity.

The project is designed as a prospective cohort study based on paired data with head-to-head comparison of CT, MRI, PET/CT and PET/MRI. Patients will be included from the head and neck cancer fast-track program at the Center of Head and Neck Cancer, Odense University Hospital (OUH).

Included patients will be offered PET/MRI in addition to the conventional fast-track imaging. The description of the images will be made blinded. When a neck dissection of the lymph nodes is made, the lymph nodes will be separated in defined regions. The diagnostic accuracy of the individual imaging modalities is assessed for each neck level with histology as standard reference.

Inclusion Criteria:

Patients either suspected of or with histologically verified:

• Relapse of head and neck squamous cell cancer with involvement of regional lymph node(s)
• Cervical lymph node metastasis with unknown primary tumor site
• Oral cavity squamous cell carcinoma
• Oropharyngeal squamous cell cancer planned for trans oral robotic surgery

Exclusion Criteria:

• Patients who cannot have a PET/MRI performed for different reasons (allergy, claustrophobia, medical implants)
• Patients who had surgery, infection or other inflammatory inducing conditions on the neck within the last 8 weeks