Investigation of GlucoCEST as novel clinical MR biomarker of glucose metabolism

Introduction Sugar (glucose) is the base fuel that drives cell function [1] . Inefficient glucose metabolism can provide clinical indication of underlying pathology. The current clinical imaging method to estimate cerebral glucose metabolism is fluoro-D-glucose (FDG) in Positron Emission Tomography (PET) [2] . MRI GlucoCEST [3] exploits the chemical exchange between mobile protons or molecules in neural tissue [4] . This technique amplifies the hydroxyl groups on glucose within the neural tissue and allowing the estimation of glucose metabolism using MRI. Methods Animal study: Experiments were performed on a 9.4T scanner: 9 transgenic AD and 10 wild type mice were fasted for 12 h [9]. CEST-sequence: GRE-TR = 6.1 ms, TE = 2 ms, flip = 5°, FOV = 20 × 20 mm 2 , thickness = 3 mm, matrix = 64 × 64 using a train of saturation pulses at 79 frequency offsets. GlucoCEST: CEST measurements were repeated for 104 min after IP injection of 1 g/Kg glucose. To measure the in-vivo glucose uptake pre-injection images are subtracting from post-injection and the area under the MTRasym curve is measured (i.e. GlucoCEST enhance (GCE)) [3] . Human study: In vivo studies were carried out on a Philips 3T scanner on one oncology patient. CEST: 2D GRE sequence resolution, 1.41 × 1.41 × 6.0 mm, TR = 1031 ms, TE1 = 1.9 ms, Δ TE = 3.04 ms, over 8 saturation frequencies. GlucoCEST: The subject arrived fasted for > 8 h and identical measures were as above were applied at every 5 min for a total of 45 min.