Dynamic glucose-enhanced MRI in brain tumors

Dynamic glucose-enhanced (DGE) MRI is an emerging imaging technique that provides information on sugar uptake with contributions from delivery (perfusion), transport (membrane permeability), and metabolism in vivo. DGE MRI contrast reflects changes in water magnetization caused by changes in sugar concentration, which can be detected through chemical exchange between water protons and sugar hydroxyl protons. Such contrast can be visualized using chemical exchange-sensitive saturation transfer (CEST), on- and off-resonance spin-lock (CESL), and $T_2$ relaxation-based approaches. These methods enable the use of biodegradable sugars as contrast agents, which are expected to have fewer side effects than conventional gadolinium-based MRI contrast agents and are more affordable and environmentally friendly. In this review, part of the special issue "New MR imaging techniques in Oncology," we provide an overview of DGE MRI and its potential applications in brain tumor imaging. We introduce the physical principles underlying the contrast mechanisms and summarize current acquisition strategies and post-processing approaches, including quantification and kinetic modeling. Technical challenges such as small signal changes, motion sensitivity, and inhomogeneities in static ( $B_0$ ) and radiofrequency ( $B_1$ ) magnetic fields are discussed. Special attention is given to glucose physiology and pharmacokinetics, including administration methods. Throughout, we summarize preclinical and early patient studies in brain tumors and compare DGE MRI with other functional and molecular imaging techniques using MRI and PET. Finally, we discuss future directions for clinical translation, emphasizing the need for standardized protocols and improved acquisition and post-processing strategies.