In contrast, Positron Emission Tomography (PET) is used to determine if tissues or tumors are metabolically active. This is important, because metabolically active tumors are more likely to be malignant.

What does metabolic activity mean on a PET scan?

Metabolic activity, as defined by the uptake of 18F-fluorodeoxyglucose (FDG) on positron emission tomography (PET), takes advantage of the physiologic preferential use of anaerobic glycolysis over oxidative phosphorylation used by malignant cells for their energetic needs.

What does it mean when a cell is metabolically active?

I am a beginner (not much expert) in the field of Microbiology, but In my opinion metabolically active bacteria means when bacteria takes up some substrate, metabolize it and release/produce some product.