Purpose: To study the relationship between standardized uptake values (SUVs) in normal tissues and body weight determined with positron emission tomography (PET).
Materials and methods: SUVs were determined in 28 nondiabetic women with newly diagnosed untreated primary breast cancers. Body weights ranged from 45 to 107 kg. SUVs for lung, liver, marrow, spleen, blood, and normal breast were determined from images obtained with PET 50-60 minutes after injection of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG).
Results: There was a positive correlation between SUV and body weight for blood, (r = .75, P = .000004), liver (r = .72, P = .000081), and spleen (r = .57, P = .033), all of which had substantial F-18 activity. In heavy patients, SUVs for those normal tissues were up to twice those of lighter patients. Calculating SUV on the basis of predicted lean body mass (SUV-Lean) eliminated the weight dependence of the SUV for blood (r = .26, P = .18) and reduced weight dependence in other tissues.
Conclusion: SUV-Lean is a weight-independent index for blood FDG accumulation at PET and may be more appropriate than SUV for quantifying F-18 activity in tumors.