[Henny]

Well Donna-here goes

A bone scan is a metabolic scan where you get injected with a labeled mineral. It goes to all the bones but wherever the bone is healing (fracture, mets, other bone diseases etc) more of the labeled mineral is taken up. It's specific for where but not what is causing the bone to remodel itself.

A PET scan is also a metabolic scan but you get injected with a labeled sugar. The sugar is taken up by cells that metabolize lots of glucose. They look for the sugar to be taken up in areas where you wouldn't expect lots of sugar to be used. It's normal to see uptake in the heart but not in the liver or lungs.

A CT scan is an xray done in 360 degrees. It doesn't have anything to do with cell metabolism. It shows the anatomy really well.

The PET/CT combines both so you get the metabolism from the PET which is fairly fuzzy with the really clear CT so when they're fused you see exactly where the cells that are growing faster are.

Right now there is a lot of discussion in radiology about bone scans vs PET scans for bone mets. Some say bone scans are better and others say PET. There is a new kind of bone scan coming out in a few places that is a specific PET bone scan (with sodium-fluoride instead of glucose) that looks like it will be a great imaging agent.

I know this doesn't help make the choices but I hope it isn't too rambling of an explanation