Faux positif du 18F-FDG TEP-TDM secondaire à la prise de metformine

The effect of MRI contrast agents on hepatic and splenic uptake in the rabbit during (99m) Tc-MDP bone scintigraphy

The objective of this study was to investigate the effects of Omniscan® and Magnevist® on (99m) Tc-MDP uptake in rabbits during (99m) Tc-MDP bone scintigraphy. In Experiment Group 1, 30 healthy adult rabbits were randomized into six subgroups (n = 5); each subgroup experienced a different time interval between injections (30 min, 60 min, 120 min, 240 min, 360 min, 24 h). All six subgroups were injected first with Omniscan®, then with (99m) Tc-MDP. After 7 days, the same six subgroups were injected with normal saline followed by (99m) Tc-MDP at the same time intervals. In Experiment Group 2, 20 healthy adult rabbits were allocated randomly to four subgroups (n = 5); each subgroup experienced a different time interval between injections (30 min, 60 min, 120 min, 240 min). All four subgroups were injected first with Magnevist®, then with (99m) Tc-MDP. After 7 days, the same four subgroups were injected with normal saline followed by (99m) Tc-MDP. In all experiments, whole-body skeletal imaging was performed. Liver, spleen, and background were delineated to determine the target-to-background (T/B) ratio. Diffusely increased intake of the imaging agent was seen in the liver and spleen when the injection-time interval between Omniscan® and (99m) Tc-MDP varied from 30 min to 240 min and when the time interval between Magnevist® and (99m) Tc-MDP was 30 min-60 min. The imaging findings are consistent with the results of L/B and S/B ratios in each experiment group. Both Omniscan® and Magnevist® have an effect on (99m) Tc-MDP uptake during bone scanning; the main effect is diffusely increased hepatic and splenic activity.

Impact of medication discontinuation on increased intestinal FDG accumulation in diabetic patients treated with metformin

OBJECTIVE

We evaluated the impact of stopping medication for 2 days on reductions in the high intestinal FDG uptake induced by metformin.

SUBJECTS AND METHODS

One hundred thirty-eight diabetic patients were divided into two groups: one in which the antihyperglycemic drug regimen included metformin (group A; n = 107) and one in which the regimen did not include metformin (group B; n = 31). Fifty-two patients without diabetes mellitus served as the control group (group C). Group A was divided into two subgroups: 77 patients (group A1) were taking metformin at the time of FDG PET/CT scans, whereas the remaining 30 patients (group A2) were asked to stop taking metformin for 2 days before PET/CT scans. In addition, 10 diabetic patients underwent two consecutive PET/CT scans before and after the discontinuation of metformin. The intestinal FDG uptake and blood glucose levels were compared among the four groups, as well as before and after the discontinuation of metformin.

RESULTS

The high intestinal FDG uptake in group A1 was significantly reduced after the discontinuation of metformin (p < 0.001 vs group A2); thus, there were no significant differences among group A2, group B, and group C (p = 0.581-0.872). There were also no statistically significant differences in the blood glucose levels among the three groups of diabetic patients (p > 0.9). In 10 patients who underwent serial PET/CT scans, mean intestinal FDG uptake decreased by 64% without significant changes in the blood glucose level. Hidden colorectal malignancies were revealed in two patients after the discontinuation of medication.

CONCLUSION

The discontinuation of metformin for 2 days is feasible for reducing the high intestinal FDG uptake induced by metformin.