In PET imaging, increased FDG uptake typically indicates which of the following?

• A. Decreased metabolic activity.
• B. Increased metabolic activity which can reflect malignancy or inflammation.
• C. Purely infectious processes.
• D. Normal aging.

Answer: (B)

In PET imaging, FDG uptake reflects cellular glucose metabolism. Cells that are highly metabolically active, such as cancer cells that rely on glycolysis, take up more FDG and show up as brighter areas. Activated immune cells during inflammation or infection also consume extra glucose, leading to increased FDG uptake. So when you see heightened uptake, it points to regions of elevated metabolic activity that can be due to malignancy or inflammatory/infectious processes. It’s not typically seen with decreased metabolism or as a normal aging change, and the finding isn’t specific to a single disease—correlation with anatomy and clinical context is needed to distinguish causes.