One of my scans came back all lit up because I had the flu the prior week. I even mentioned this to the technicians and asked if I should reschedule. ...Spots on lungs...active lymph nodes... The doctors called my wife and left messages like 'We got the test back and call back immediately etc...'. Freaked out the wife. They just tested me 30 days later and it came back all clear. Bottom Line - pet scans don't detect cancer - biopsies do.