In PET imaging, what does the liver and spleen show indicative of normal FDG uptake?

In PET imaging, the liver and spleen typically demonstrate low-grade diffuse activity indicative of normal FDG uptake. This pattern is expected because both organs are involved in glucose metabolism and play a role in various metabolic processes within the body.

The liver is responsible for processing nutrients, and while it showcases some metabolic activity with FDG uptake, it does not exhibit high levels of uptake in the context of normal physiological conditions. Instead, the low-grade uptake reflects a baseline level of activity that is typical for healthy liver tissue. Similarly, the spleen, which is involved in immune function and cellular removal, will show low-grade diffuse activity as well, representing its normal metabolic function without any excessive or pathological accumulation of FDG.

This understanding of the expected normal activity in these organs is essential for interpreting PET scans appropriately, as deviations from this pattern can indicate potential pathology, such as inflammation, infection, or malignancy.