Oncology constitutes 75% of all clinical studies of positron emission tomography (PET). Glucose metabolism is increased in lung cancers like the other cancer cells. Integration of 18F-fluorodeoxyglucose (FDG) PET and computed tomography (CT) provides both anatomic and metabolic knowledge. PET-CT has an important role in lung cancer staging. Here, two cases of FDG microembolus were presented. Although there was an FDG uptake in PET-CT, it was not seen in CT images.