This study aims to validate a non-invasive quantitative imaging method of whole tumors using a novel PD-L1 positron emission tomography (PET) tracer in patients with head and neck cancer who undergo resection of primary tumor and locoregional lymph node metastases thus providing an excellent model to perform correlative studies with immunohistochemistry (IHC).~The investigators will extend the study to patients with brain metastases because there is a critical need for a non-invasive test for PD-L1 in this population, as biopsy of these lesions is rare.~In this study, the investigators will image patients with brain metastases, which are predominantly from lung cancer and melanoma, that are planned to undergo biopsy. The ultimate goal of this research is to validate quantitative PD-L1 PET imaging in determining PD-L1 expression within primary and metastatic cancer without the need for biopsy and identify parameters of PD-L1 quantitative PET that will allow its translation into clinical practice. This method can then be used to determine which patients may benefit from immunotherapy.~The primary objective of this study aims to test the difference in non-invasive quantitative PD-L1 PET measures (VT) of lesions between different groups of PD-L1 levels (PD-L1 ≥90% vs <1%) in head and neck cancer primary lesions.~Secondary objectives:~To establish lesion level association between immunohistochemistry measures of PD-L1 levels within primary head and neck cancer lesions (as the outcome) and PD-L1 PET measures (VT);~To establish lesion level association between immunohistochemistry measures of PD-L1 levels within locoregional metastases within the neck and resected normal lymph nodes (as the outcome) and PD-L1 PET measures (VT).~To establish lesion level association between the degree of tumor inflammatory cell infiltration on IHC in primary head and neck squamous cell carcinoma (SCC) lesions (as the outcome) and PD-L1 PET measures (VT);~To establish lesion level association between the degree of tumor inflammatory cell infiltration on IHC in metastatic head and neck SCC lesion (as the outcomes) and PD-L1 PET measures (VT).~Tertiary objective:~To establish lesion level correlation of IHC measures of total/tumor/inflammatory cell PD-L1 levels to PD-L1 (VT) on PET in brain metastases
This study aims to determine the feasibility of non-invasive quantitative PD-L1 measurement using [a novel PD-L1 positron emission tomography (PET) tracer and perform immunohistochemistry based measurement of PD-L1 levels within resected lesions in head and neck cancer and brain metastases.