A patient scheduled for an oncological FDG PET-CT reports drinking several sugary drinks two hours before injection. How does this most affect the study?
- A Tumour SUV increases because of competitive substrate loading
- B No significant change, since tumour glucose use is insulin independent
- C Tumour FDG uptake falls and skeletal muscle plus myocardial uptake rises, degrading lesion detectability ✓
- D CT attenuation correction fails because of altered blood density
Correct answer: C. Tumour FDG uptake falls and skeletal muscle plus myocardial uptake rises, degrading lesion detectability
Explanation
Hyperglycaemia competes with FDG for GLUT-mediated entry, reducing tumour-to-background contrast and lowering measured SUVs. Insulin released in response to the glucose load drives FDG into skeletal muscle and myocardium, producing diffuse muscular uptake that can obscure lesions. This is why patients fast for 4 to 6 hours and serum glucose is checked before injection. Tumour uptake does rise with hyperglycaemia, attenuation correction is unrelated to blood sugar, and muscle uptake changes are substantial.
Reference: Brant and Helms Fundamentals of Diagnostic Radiology, 5th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.