Tony -- Even though you did not have neck dissection, the effects of treatment are profound. Just the radiation causes anatomic changes on CT that a radiologist has to be very, very experienced with to recognize. Even then, everyone is different, so they often use the first PET simply as a baseline, and go from there afterwards. Lots of threads here on false positive PET scans.

My first PET showed a couple of lymph nodes, and both my surgeon and RO said not to worry. I am having it redone on Tuesday, but am not really concerned, as my neck has not changed a bit in terms of lumps and bumps, and I would have expected to have started seeing something had these been truly malignant nodes. Maybe not, but it makes me feel better. ;-) Take care.