Usefulness of Integrated PET/MRI in Oropharyngeal Squamous Cell Carcinoma Evaluation

Head and neck cancer (HNC) continues to be a significant health care problem in Taiwan and oropharyngeal squamous cell carcinoma (SCC) is the common subtype. With the concern of organ preservation in recent years, concurrent chemoradiation is the major treatment modality for oropharyngeal SCC, while endoscopy with biopsy serves as the main diagnostic tools. With the advance of MRI technology, whole body MRI is now possible, and functional techniques become more feasible in the head and neck region, including diffusion-weighted imaging (DWI) which comprises of monoexponential DWI, intravoxel incoherent motion (IVIM) model and Kurtosis (biexponential or non-Gaussian fitting), and dynamic contrast-enhanced perfusion weighted MRI (DCE-PWI) become feasible. Therefore, MRI can evaluate distant site status of HNC in the single examination session and provide biologic information of tumors. Positron emission tomography/CT (PET/CT) is another common imaging modality to evaluate HNC, because of its ability to provide whole-body anatomic and metabolic information. Integrated PET/MRI is a novel imaging technology that combines PET and MRI in one single scanner. In this 3-year prospective study, the investigators will take the advantages of integrated PET/MRI scanner with DWI (including monoexponential, kurtosis and IVIM modes) and DCE-PWI to evaluate our 160 patients with oropharyngeal SCC subjected to chemoradiation. Non-contrast chest CT will also be performed on the same day. The investigators aim to determine whole-body staging/restaging accurately, to predict treatment response and prognosis, and to determine necessity of noncontrast chest CT. The investigators expect that this project will offer the validation of usefulness of integrated PET/MRI in tumor staging/restaging of oropharyngeal SCC and resultant clinical impact. The role of noncontrast chest CT in the workup with our PET/MRI protocol can be defined. It will also provide evidence about how and to what extent th