How PET/CT Works?
While a CT scan provides anatomical detail (size and location of the tumor, mass, etc.), a PET scan provides metabolic detail (cellular activity of the tumor, mass, etc.). Combining these two scanner technologies makes a PET/CT superior to either technology alone.1 Anatomical CT scanners send x-rays through the body, which are then measured by detectors in the CT scanner. A computer algorithm then processes those measurements to produce pictures of the body’s internal structures. Metabolic PET images begin with an injection of a solution of glucose (sugar) that has been “tagged” with a radioactive chemical isotope (generally fluorine 18, or FDG). Metabolically active organs or tumors consume sugar at high rates, and as the tagged sugar starts to decay, it emits positrons. These positrons then collide with electrons, giving off gamma rays, and a computer converts the gamma rays into images. These images indicate metabolic “hot spots,” often indicating rapidly growing tumors (because can
