This phase II trial studies how well fluorine F 18 Ara-G positron emission tomography
(PET)/magnetic resonance (MR) imaging works in measuring clinical response to atezolizumab or
patients with cancer receiving standard of care Anti-PD-1/L1. Diagnostic procedures, such as
fluorine F 18 Ara-G PET/MR imaging, may help measure a patient's response to standard of care
atezolizumab or Anti-PD-1/L1 treatment.