Inclusion Criteria:  Patients ≥ 18 years old at the time of informed consent Ability to provide written informed consent and HIPAA authorization Primary or recurrent invasive cutaneous squamous cell carcinoma of the head or neck, clinically staged T2-T4 based on AJCC staging Clinically and radiographically regional node-negative (no evidence of regional lymph node metastasis or distant metastasis) Able to undergo general anesthesia for sentinel lymph node biopsy Able to undergo CT scan with contrast or MRI with contrast Undergo surgical resection (Moh's or micrographic resection or standard excision with sentinel lymph node biopsy) within 4 weeks of imaging  Exclusion Criteria:  Clinical evidence of satellite lesions, in-transit, regional nodal or distant metastases Known biopsy proven synchronous primary cutaneous squamous cell carcinoma Pregnant patients Patients unable to undergo general anesthesia Patient unable to receive contrasted imaging studies Patient unable to receive and/or allergic to 99m-Technetium sulfur colloid