Purpose: To reevaluate the relationships between standardized uptake values (SUVs) and body weight by using positron emission tomography (PET) with 2-[fluorine 18]fluoro-2-deoxy-D-glucose (FDG).
Materials and methods: FDG PET scanning was performed in 138 female patients with known or suspected primary breast cancers. SUVs in blood and tumor (n = 79) were calculated by using body weight (SUVbw), ideal body weight (SUVibw), lean body mass (SUVlbm), and body surface area (SUVbsa) on images obtained 50-60 minutes after the injection of FDG.
Results: There was a strong positive correlation between the blood SUVbw and body weight (r = 0.705, P < .001). The blood SUVibw reduced the weight dependence but showed a negative correlation with body weight (r = -0.296, P < .001). Both the blood SUVibm and SUVbsa eliminated the weight dependence and showed no correlation with body weight (r = -0.010, P = .904 and r = 0.106, P = .215, respectively). Although there was a wide variance in the tumor SUVbw, it showed a weak but significant positive correlation with body weight (r = 0.207, P = .033). Plots of the tumor SUVlbm and SUVbsa versus body weight showed relatively flat slopes.
Conclusion: SUVlbm and SUVbsa are weight-independent indices for FDG uptake, and SUVlbm appears to be more appropriate for quantifying FDG uptake to avoid overestimation of glucose utilization in obese patients.