PET scans are hardly worthless. The PET/CT accuracy is at least 95% I understand. The Older PET scans were less accurate because there was no anatomical point of reference or spacial registration accuracy. Yes there are some false positives with PET and PET/CT and there are many false positives with many lab tests. The PET amd PET/CT have tremendous value in both pre Tx triage and post Tx analysis of Tx efficacy.

There have been many here who have had recurrences caught early as a result of a PET or PET/CT. Scans in general are only a component of a diagnostic workup. I have had MRI's with ROI that turned out to be nothing and the MRI is considered the gold standard of imaging.