We have done PET for original diagnosis and pre-surgically to rule out mets in lungs before doing Ivor-Lewis (surgery contraindicated by mets). Also did PET to restage when CT showed beginning of lung mets return in area we had resected since we thought it could be scar tissue and metabolic activity ruled that out. During 3rd round of chemo, we began having trouble with Blue Cross covering PET-they will not allow if for restaging EC (but will allow it for nodules in lungs if they call it lung cancer). That's okay with me in a way because I don't really like the idea of shooting my husband full of radioactive tracer, etc (there are cancer risks with the diagnostics too). If we were to see new nodules on a CT we would probably do a PET to identify if it was metastasis or something else, but after already knowing there is something there, a CT would be enough to show you if it was shrinking or not in chemo so I'm guessing that is the rationale behind using CT. The new 64 slice CT's use less radiation, so the risk is smaller using them.