To add a little personal experience, I've had 3 PET/CT scans done at Adventist in Hong Kong, they're affiliated with Soan-Kettering some way. The worry about the false-positive comes from the way the PET part works. The PET as I understand it shows cellular activity, actually I think an uptake in glucose levels. Cancer cells are more active, so they would show increased cellular activity.

Problem is, infected lymph nodes, and damaged muscles in the healing process sometimes also show increased uptake.

My doc seems to be of the opinion that the tests might be as high as 20% false positive, but that MRI isn't any more accurate actually.

This last go around, the tests showed 3 suspicious nodes, with one being real suspicious. Needle biopsy confirmed the cancer so during the neck dissection they removed amoung others, all three nodes. 2 were cancerous, the third and some others were infected.

In a nutshell, I'd still reccomend the PET/CT based on my experience. The other good part of it is that the PET/CT computer data can be used to program the IMRT equipment for a higher degree of accuracy.

Hope this helps, I'd have to check my insurance billing, but the price seems a little steep for the test though.
Bob