Optimization of whole-body positron emission tomography imaging by using delayed 2-deoxy-2-[F-18]fluoro-D: -glucose Injection following I.V. Insulin in diabetic patients

Abstract

Purpose: High blood glucose levels may decrease the sensitivity of 2-deoxy-2-[F-18]fluoro-D: -glucose (FDG)-positron emission tomography (PET). The goal of this study was to assess whether intravenous (i.v.) insulin followed by FDG injection 60 minutes later could decrease the blood glucose level of hyperglycemic patients without altering muscular, liver, or lung FDG uptake.

Methods: We evaluated 53 diabetic patients with a fasting glycemia higher than 7.0 mmol/l. The control group consisted of 53 nondiabetic patients with a normal fasting glycemia. Sixty minutes before FDG injection, all diabetic patients received up to two intravenous bolus of insulin. Regions of interest were drawn over the lungs, heart, liver, skeletal muscles, and over the most active lung nodule, if present, to calculate a standardized uptake value (SUV) normalized to the lean body weight.

Results: After one or two boluses of insulin (mean 3.4 units), 39 diabetic patients decreased their blood glucose level from 9.4 +/- 1.8 to 6.1 +/- 1.3 mmol/l. In 14 patients, two doses of insulin (mean 4.5 +/- 2.3 units) were not sufficient, but managed to decrease the blood glucose level from 10.6 +/- 2.1 to 9.1 +/- 2.1 mmol/l. There was no significant difference for the SUV calculated on the lung, liver, heart, and skeletal muscles. No differences were noted in lung tumor uptake in patients who received insulin compared to the control group.

Conclusions: With a sufficient waiting period between the insulin and FDG injections, an i.v. bolus of insulin makes it possible to effectively decrease glycemia of diabetic patients without increasing muscular FDG uptake.