Images produced from new medical technologies that incorporate PET are similar weather map you see on your local news. The radar images reveal the size and intensities of storms while the topological map of the United States displays an accurate depiction of the geographic features of the land. When one image is overlaid with the other, people can see what areas are being affected by adverse weather so they can respond quickly.
In the same sense, by overlaying PET and CT (computational tomography) or MR (magnetic resonance) images physicians can more accurately locate, diagnose and treat disease at an earlier stage.
CT and MR scans are the topological maps that can show broad areas of morphology while PET acts as the radar map that can show speciﬁc regions of biological or chemical changes within that morphology.