The effect of furosemide dose timing on bladder activity in oncology imaging with 18F-fluorodeoxyglucose PET/CT.

Objective: To compare the effects of two furosemide administration protocols on bladder activity during 18F-fluorodeoxyglucose (18F-FDG) PET/computed tomography (CT) imaging.

Methods: A total of 109 consecutive patients with known or suspected malignancy, meeting our inclusion criteria, were chosen over a discrete time period. Group 1 (n=39) received furosemide 20 mg intravenous 15 min before PET/CT imaging (i.e. approximately 45 min after 18F-FDG administration). Group 2 (n=45) received furosemide 20 mg intravenous 15 min after 18F-FDG. Group 3 (n=25) did not receive furosemide and served as controls. Bladder standard uptake values (SUVs) and volume, and liver SUV data were collected.

Results: Relative to the control group, both furosemide groups showed significantly lower mean and maximum SUV bladder activities (P<0.001), lower mean bladder-to-liver SUV ratios (P<0.001), larger mean bladder volumes (P<0.001) and higher proportions of bladder PET/CT image mis-registration. Patients tolerated earlier administration of furosemide (group 2) better relative to urinary urgency during imaging.

Conclusion: The use of a relatively simple diuretic protocol can significantly lower bladder FDG activity and potentially improve image quality by reducing bladder activity artifacts and avoid invasive bladder catheterization. Administering furosemide earlier after FDG injection (i.e. 15 min) versus later (i.e. 15 min before imaging) appears to be better tolerated by patients.