A 40-year-old woman admitted with fever of unknown origin for three weeks has negative cultures and unrevealing CT scans. FDG PET-CT is performed. What is the principal value of FDG PET in this setting?
- A It replaces the need for blood cultures entirely
- B It definitively distinguishes bacterial from viral infection by SUV thresholds
- C It identifies occult foci of infection, inflammation or malignancy, guiding biopsy of metabolically active sites ✓
- D It is contraindicated because fever causes false-negative scans
Correct answer: C. It identifies occult foci of infection, inflammation or malignancy, guiding biopsy of metabolically active sites
Explanation
Activated leucocytes, granulomas and many malignant cells all use glucose avidly, so FDG PET-CT frequently localises occult infectious, inflammatory or neoplastic foci in fever of unknown origin and directs biopsy to the most productive site. It cannot reliably separate bacterial from viral or sterile inflammation by SUV alone, so histology or culture remains necessary. Blood cultures are unaffected, and fever itself does not abolish FDG uptake; false negatives relate mainly to recent steroids or neutropenia.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.