My experience with diagnostic PET scans were two false positives with high SUV values (5.9) showing "concerns" on the right side of my mouth and tongue. Both PET scans completely missed the tumor growing back on the left side of the base of my tongue, which my ENT found by palpitation one month after the PET scan.
I have had 4 PET scans, the other two were to provide images for the radiologist to program the IMRT and now the CyberKnife field of radiation. I will stick with MRIs from now on,
PET scans just measure sugar uptake - which can be caused by inflammation or even exertion. Hope yours is just a false positive also,