The goal of this observational study is to explore the application of temporal diffusion spectroscopy MRI in head and neck squamous cell carcinoma (HNSCC).

The main questions it aims to answer are:

• If the quantitative parameters of temporal diffusion spectroscopy MRI can predict the comprehensive positive score (CPS) of pathological PD-L1 expression in HNSCC?
• If the quantitative parameters of temporal diffusion spectroscopy MRI can predict the efficacy of neoadjuvant therapy in HNSCC? Participants will receive head and neck MRI, including T2WI, T1WI, diffusion-weighted imaging (DWI), oscillating gradient spin echo (OGSE) and pulsed gradient spin echo (PGSE) sequence before and after neoadjuvant therapy.

There is not a comparison group in our study.

Inclusion Criteria:

• Patients first diagnosed with head and neck squamous cell carcinoma (HNSCC) by pathological biopsy
• Patients proposed to receive 2-3 courses of neoadjuvant chemotherapy and immunotherapy
• Patients without contraindications for MRI, such as nonremovable ferromagnetic metal foreign body, claustrophobia, renal insufficiency, and previous history of gadolinium contrast allergy

Exclusion Criteria:

• Less than 10mm in the maximum diameter of the baseline primary tumor
• Poor MRI image quality with obvious metal or motion artifacts
• The failure to complete the course of neoadjuvant therapy

The patients first diagnosed with HNSCC by pathological biopsy and proposed to receive preoperative neoadjuvant therapy at Sun Yat-sen Memorial Hospital