My point was that it wasn't really a false negative. Your ENT may "see" something on the PET, but the point is that your RO and the reading radiologist quite likely "saw" the same thing, but attributed it to either normal metabolic activity or inflammatory changes from treatment. Your ENT is likely being ultra cautious.

In the course of my experience with the dreaded PET, I spoke with many people and read a lot about these exams. It takes a lot of technical skill and a lot of artistry to not only read them but to understand what that reading means in context. You can read lots of literature that says an SUV of 3.0 or higher is strongly indicative of cancer. Yet that does not necessarily apply to post treatment head and neck cancer patients.

Follow through with your ENT, but do not be suprised if your RO and reading radiologist were correct. These difficulties are the reason many will not use PET at all, and others only as an adjunct in post-treatment Head & Neck Cancer.