How do a pet scan and a ct scan differ?

Anatomic/physiologic: Pet scan involves intravenous injection of radio tracer usually f18 fdg.Imaging of whole body occurs for localization of areas of increased glucose metabolism. Malignant tumors usually most active.Ct scan involves x-ray and performs anatomic imaging of parts of body usually head, chest, abdomen, pelvis, or extremities. Pet?Ct combines imaging modalities for anatomic localization of areas of uptake.

PET vs. CT: Pet scan usually refers to pet/ct where pet and ct scans are acquired ; fused to take advantage of both functional and anatomic information. At some institutions, the ct performed with pet is a low dose ct and does not include oral or IV contrast. Other institutions perform a high (full dose) ct with IV and oral contrast which provides better quality images and the advantage of contrast.