What is the difference between normal ct and pet ct scan?

PET/CT vs. CT: Pet/ct scan has 2 sets of images (pet ; ct images) which are fused for interpretation. The ct part provides anatomic info while the pet part provides functional info (glucose distribution/metabolic activity). Sometimes the ct part of pet/ct is done as low dose ct without IV or oral contrast. These images are suboptimal compared to a separate dedicated ct with hi dose ; IV and oral contrast.

Nuclear study: Ct radiographic examination by itself is usually more detailed with higher resolution utilizing intravenous contrast material to help differentiate soft tissue abnormalities such as lymph nodes from vascular structures. Ct combined with pet, is low resolution but helps define areas of increased radiotracer uptake of isotope f18 fdg, glucose metabolite, by allowing anatomic localization.