This is because PET scanning uses the principle of imaging critical physiologic pathways rather than simply the existing anatomy.
Tumors generally grow faster than their normal tissue counterparts.
While amino acid analogs and DNA precursors can be used, the use of glucose analogs has proven to be most successful. The observation of increased aerobic glycolysis by tumor and the ability to detect this process has allowed the most practical utilization of PET scanning. Pet scanning in oncology dates back to 1982. PET scanning was initially utilized to distinguish recurrent disease from radiation necrosis. PET was also used to distinguish low grade from high grade gliomas.