Non-Invasive Cerenkov Luminescence Imaging of Lymphoma, Leukemia and Metastatic Lymph Nodes

Inclusion Criteria: * Participant is 18 years of age or older. * Participant is scheduled for standard clinical and/or investigational PET/CT scan or 131I therapy within the Nuclear Medicine Service at Main Hospital. * Patients must have had pathologic lymph node metastases in the neck, axillary or inguinal area (do not need to be biopsy proven) from either leukemias, lymphomas: , Head and Neck cancers (e.g. tonsillar, nasopharynx, tongue carcinoma, breast cancer or melanoma;or lymphoma or tonsillar or squamous cell carcinoma with metastases in the neck region for PET/CT imaging, or thyroid cancer for thyroid ablation therapy. Any other more infrequent cancer metastasizing with nodal metastasis in the neck, axilla and inguinal regions to cervical lymph nodes is eligible as well as the primary goal is to image pathological (i.e. hypermetabolic) lymph nodes. * Patients with hypermetabolic activity and uptake in the neck,axilla, breast and inguinal region on scan, defined visually as significant lesion suspicious for malignancy by a nuclear medicine physician or trainee. (We will include a subset of patients with normal lymph nodes during screening. This subset of patients will be imaged as a negative control for this study.) Exclusion Criteria: * Patients imaged for Cerenkov luminescence are going to be required to be in a darkened enclosure for at least 10 minutes and sit still during image acquisition, potentially covered by a dark cloth in case that the ambient light level remains too high for the ultra-sensitive camera. Any conditions that would prevent this will exclude the patients. * There are any other past medical, physiological or demographic concerns. This includes any patients with skin blemishes that are present at the dermis over the tumor, as these are of particular interest for use of this technique.