PET scans: here ,here , here , here, here , here and more PET Scans  

PET showing lymph node spread here, and a PET is much better than a CT in determining if the lymph nodes are cancerous see here , here , here and  here CT of nodes here, Pet can separate cancer from pneumonia (go here) and can distinguish between cancer and collapsed lung (here , here and here)

The PET will which parts of the tumor has active or growing cells (called hypermatabolic because they are using more glucose than normal cells) and which parts of the cancer may be no longer growing or even dying off (called necrotic) from lack of oxygen due to out growing their blood supply (see here)

More comparisons showing PET superior to CT here , here, here , here and here