Clockwise: As all the agonists assemble, rads have rightfully questioned whether so many GLP-1s alter FDG biodistribution. Short answer via the Best Oral Presentation Abstract in Nuclear Medicine at ARRS26: nope.
Why Wait? Concerns regarding “muscle mapping” or altered bowel uptake have led to additional uncertainty about whether patients should pause their medication or time their scans around their injection schedule. Led by Anna Eshghi, researchers from the University of Arkansas for Medical Sciences suggests such precautions are unnecessary.
Eshghi et al. retrospectively analyzed 126 patients on GLP-1 therapy, including a paired comparison of 36 patients who had scans both before as well as after starting the medication.
- Stable Biodistro: No statistically significant differences in FDG uptake were found in the liver, blood pool, skeletal muscle, or abdominal fat.
- Brain Exception: The only significant SUV change was in whole-brain SUVmean (p=0.0274), which correlated with improved blood glucose levels.
- Timing is Irrelevant: Variations in GLP-1 dosing (ranging from 0 to 10 days before the scan) did not significantly impact FDG biodistribution.
- Metabolic Trends: While mean blood glucose dropped (124.8 to 111.1 mg/dL) and BMI decreased (37.5 to 34.7), these changes did not trigger “muscle-heavy” scans.
RadFYI: FDG PET/CT remains reliable in patients on GLP-1 therapy regardless of their last injection date. Rather than focusing on injection timing, clinicians should prioritize maintaining appropriate blood glucose levels prior to the scan to ensure optimal brain FDG uptake and SUV accuracy.
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