In vitro and in vivo comparison of the MRI glucoCEST properties between native glucose and 3OMG in a murine tumor model

Purpose D-Glucose and 3-O-Methyl-D-glucose (3OMG) have been shown to provide contrast in MRI-CEST images. However, a systematic comparison between these two molecules has not yet been performed. This study dealt with the assessment of the effect of pH, saturation power level (B1) and magnetic field strength (B) on the MRI-CEST contrast with the aim of comparing the in vivo CEST contrast detectability of these two agents in the glucoCEST procedure. Methods Phosphate buffered solutions of D-Glucose or 3OMG (20 mM) were prepared at different pH values and Z-spectra acquired at several B1 levels and at 37°C. In vivo glucoCEST images were obtained at 3 T and 7 T over a period of 30 min after injection of D-Glucose or 3OMG (at the doses of 1.5 and 3 g/kg) in a murine melanoma tumour model. Results A markedly different pH dependence of CEST response was observed in vitro for D-Glucose and 3OMG. The glucoCEST contrast enhancement in the tumour region following the intravenous administration (at the dose 3 g/kg) resulted to be comparable for both the molecules: 1-2% at 3 T and 2-3% at 7 T. The ST% resulted almost constant for 3OMG over the 30 min period, whereas a significant increase in the case of D-Glucose was detected. Conclusion Our results show similar CEST contrast efficiency but different temporal kinetics for the metabolizable and the non-metabolizable glucose derivatives in tumour murine models when administered at the same doses. ### Competing Interest Statement The authors have declared no competing interest. * [18F]-FDG : 2-Deoxy-2-[18F]-Fluoroglucose 2DG : 2-Deoxy-D-glucose 2OMG : 2-O-Methyl-D-glucose 3OMG : 3-O-Methyl-D-glucose 6DG : 6-Deoxy-D-glucose B0 : Magnetic Field Strength B1 : Saturation Power Level CESL : Chemical Exchange-Sensitive Spin-Lock CEST : Chemical Exchange Saturation Transfer CT : Computed Tomography DGE-MRI : Dynamic Glucose Enhanced MRI GlcN : Glucosamine GlcNAc : N-Acetyl-Glucosamine glucoCEST : D-Glucose Chemical Exchange Saturation Transfer GLUT-1 and 3 : Glucose Transporters 1 and 3 MRI : Magnetic Resonance Imaging PBS : Phosphate-Buffered Saline PET : Positron Emission Tomography ROI : Region of Interest ST : Saturation Transfer