Question

In medical oncology, PET (positron emission tomography) is used to selectively image tumors in the body and to monitor cancer progression and response to treatment. Before performing a PET scan, the patient should fast for at least several hours for blood glucose to be sufficiently low. At the time of the scan, the positron-emitting glucose analog fluorodeoxyglucose (FDG) is injected into the bloodstream and the patient is asked to wait for up to an hour while avoiding physical activity. Finally, the scanner moves slowly over the body to reveal the location of possible tumors. Why do you think the patient should avoid physical activity before the scan?

a.To prevent the absorption of the radioactive tracer by healthy tissues
b.To prevent the Warburg effect
c. To accelerate glucose uptake by the tumor cells
d. To prevent glycolysis in tumor tissues

Answer 1

Patients are advised to avoid physical activity before a PET scan to prevent the absorption of FDG by healthy tissues, enabling the scan to more selectively image tumors due to their high glucose consumption.

Step-by-step explanation:

Before a positron emission tomography (PET) scan, it is necessary for a patient to avoid physical activity after receiving an injection of the fluorodeoxyglucose (FDG) tracer. The reason for avoiding physical activity is a. To prevent the absorption of the radioactive tracer by healthy tissues. Physical activity could increase the uptake of FDG by normal, healthy tissues due to the increased demand for glucose during exercise, which could potentially obscure the PET scan results. Since cancer cells consume glucose at a high rate for their rapid reproduction, minimizing glucose uptake by normal tissues helps ensure that the scan more selectively illustrates the metabolic activity in cancer cells, creating distinct hot spots on the scan images that are indicative of possible tumors.