How is a PET scan performed

A positron-emitting radionuclide is injected into the body. As the positrons are emitted and travel through tissue they collide with electrons, resulting in production of gamma rays. A PET scanner records and analyzes these data and creates an image. CT or MRI may be combined with PET to maximize diagnostic potential.

FDG is currently the most commonly used radiotracer. It is transported and becomes trapped intracellular^ as a result of phosphorylation by hexokinase. FDG accumulates at sites of neoplasia and inflammation as cells in these regions have an increased metabolic rate. Because FDG competes with nonradioactive glucose, recent eating or diabetes with an elevated blood sugar greater than 150 mL/dL will decrease scan sensitivity. 18-F-NaF is a bone-specific tracer that has application in PET imaging of the musculoskeletal system (Fig. 13-6).

Figure 13-5. Anterior and posterior views of a bone scan show a patient with multiple foci of intense activity involving the ribs, spine, skull, right scapula and pelvis due to metastatic cancer. (From Pretorius ES, Solomon JA. Radiology Secrets, 2nd ed. Philadelphia: Mosby, 2006. p. 412)

Figure 13-6. Normal 18-F-fluoro-deoxy-D-glucose (FDG) positron emission tomography (PET) scan shows mild diffuse uptake throughout the bowel (a normal variant), mild uptake in the liver, significant uptake in the brain and heart, and marked uptake in the bladder. (From Pretorius ES, Solomon JA. Radiology Secrets. 2nd ed. St. Louis: Mosby; 2006. p. 401.)

Figure 13-5. Anterior and posterior views of a bone scan show a patient with multiple foci of intense activity involving the ribs, spine, skull, right scapula and pelvis due to metastatic cancer. (From Pretorius ES, Solomon JA. Radiology Secrets, 2nd ed. Philadelphia: Mosby, 2006. p. 412)

Figure 13-6. Normal 18-F-fluoro-deoxy-D-glucose (FDG) positron emission tomography (PET) scan shows mild diffuse uptake throughout the bowel (a normal variant), mild uptake in the liver, significant uptake in the brain and heart, and marked uptake in the bladder. (From Pretorius ES, Solomon JA. Radiology Secrets. 2nd ed. St. Louis: Mosby; 2006. p. 401.)

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