23. Improving Reproducibility of SUV by FDG Dose Adjusted for Body Size and Serum Glucose Level

Purpose: The study evaluates whether adjusting the dose of FDG injected by the patient's body surface area and the serum glucose level will produce a SUV with less standard error.

Methods: The study is a prospective study. For the period of 4/1999–5/1999, the patient received various dose of FDG as available from radiopharmacy. The Standardized Uptake Value Maximum (SUVmax) and Standardized Uptake Value Average (SUVavg) of the liver were calculated for PET scans at 40-50 minutes after injection. This is the control group. For the period of 6/1999–10/1999, the patients receiving a standard dose of FDG normalized by adjusting 15 mCi. per 1.73 sq.m. body surface area (BSA) and a proportional adjustment factor for serum glucose (serum glucose level / 5 mMol.). BSA is calculated by the formula = 0.007184 × (cm. height)^0.725 × (kg. weight)^0.425. The SUVmax and SUVavg of the liver at 40-50 minutes after injection. This is the study group.

Results and Conclusion: There are 29 subjects in the control group (CG) and 32 subjects in the study group (SG). Dose of FDG given ranges from 7.8–15 mCi in the CG, to 15.5–16.5 mCi in the SG. In the CG, liver SUVmax = (2.3 +/− s.d.0.37), SUVavg = (1.72 +/− s.d. 0.38). In the SG, liver SUVmax = (2.13 +/− s.d. 0.26), SUVavg = (1.88 +/− 0.22). The study shows that the liver SUVmax and SUVavg has a 42%, 72% respectively narrower standard deviation when the dose is adjusted for patient's body surface area and serum glucose level. This implies that such approach gives a more reproducible measurement of SUVmax and SUVavg in assessing tumor lesion.