Low-dose oral propranolol could reduce brown adipose tissue F-18FDG uptake in patients undergoing PET scans

Fluorine-18 fluoro-2-deoxy-D-glucose (FDG) uptake in brown adipose tissue (BAT) may generate FDG-PET scan misinterpretation. Recent studies have shown reduced FDG uptake in BAT in rats treated with high doses of the beta-blocker propranolol. The aim of this observational study was to present a cohort of patients with high FDG uptake in BAT who underwent a second scan after receiving a low dose of propranolol, to determine whether the use of this premedication could improve the diagnostic confidence of FDG-PET scans by inhibition FDG uptake in BAT, and also whether administration of this drug affects tracer uptake in tumors. Methods: Twenty-six cancer patients, presenting with increased BAT FDG uptake, were selected prospectively. On a different day, patients were given propranolol 20 mg orally 61) minutes prior to FDG administration 185-277.5 MBq (5-7.5 inCi) and were scanned again. Basal and postpropranolol BAT SUVmax, and tumor SUVmax (when present) were measured. Results: Mean basal BAT SUV,(max) was 5.52 +/- 2.3. Mean postpropranolol SUVmax was 1.39 +/- 0.42 (P < 0.0001). In 11 patients, the SUVmax was 8.07 +/- 6.4, and 7.88 +/- 5.9 in basal mean tumor SUVmax postpropranolol scans (P= 0.53). Nine patients showed mediastinal FDG uptake in the basal scan, affecting image interpretation. This was not observed in postpropranolol scans. No adverse effects due to propranolol were encountered. Conclusions: In this patient cohort, there was significant reduction of FDG uptake in BAT following propranolol administration, allowing for adequate interpretation of FDG-PET and software-fused FDG-PET with CT images, particularly in the mediastinal area, without affecting tumor tracer uptake.