Challenges in glucoCEST MR body imaging at 3 Tesla

Abstract

Background: The aim of this study was to translate dynamic glucose enhancement (DGE) body magnetic resonance imaging (MRI) based on the glucose chemical exchange saturation transfer (glucoCEST) signal to a 3 T clinical field strength. Methods: An infusion protocol for intravenous (i.v.) glucose was optimised using a hyperglycaemic clamp to maximise the chances of detecting exchange-sensitive MRI signal. Numerical simulations were performed to define the optimum parameters for glucoCEST measurements with consideration to physiological conditions. DGE images were acquired for patients with lymphomas and prostate cancer injected i.v. with 20% glucose. Results: The optimised hyperglycaemic clamp infusion based on the DeFronzo method demonstrated higher efficiency and stability of glucose delivery as compared to manual determination of glucose infusion rates. DGE signal sensitivity was found to be dependent on T 2 , B 1 saturation power and integration range. Our results show that motion correction and B 0 field inhomogeneity correction are crucial to avoid mistaking signal changes for a glucose response while field drift is a substantial contributor. However, after B 0 field drift correction, no significant glucoCEST signal enhancement was observed in tumour regions of all patients in vivo. Conclusions: Based on our simulated and experimental results, we conclude that glucose-related signal remains elusive at 3 T in body regions, where physiological movements and strong effects of B 1 + and B 0 render the originally small glucoCEST signal difficult to detect.

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

“…Consequently, at the higher magnetic field strength of 7 T a detectable difference between the two doses was observed, whereas at lower magnetic field strength (3 T), a clear difference between the two doses was not detected. A similar decrease in the theoretically achievable glucoCEST contrast between 7 T and 3 T was recently reported from simulated data in a tumour-like tissue 21 and a small if not elusive CEST contrast was detected in cancer patients following glucose administration at 3T 38,39 . Our results are in line with those reported in literature, despite the different experimental conditions (including B0 field, B1 saturation level and duration, administration route and doses, as well as image analysis) hamper any clear comparison among studies and between molecules.…”

Chemical exchange sensitive MRI of glucose uptake using xylose as a contrast agent

“…However, the high rate of hydroxyl‐water exchange hinders CESL and CEST application of glucose and analogs at lower fields. Recent studies at 3 T have shown that it is difficult to detect tumor contrast in human patients using 25 g of glucose with CEST, 44 and the sensitivity is weak with CESL 45 . Compared to glucose, xylose‐CESL has about 70% higher area under the curve using the same dosage.…”

Non-invasive Investigation of Tumor Metabolism and Acidosis by MRI-CEST Imaging

“…Overall, these results suggest that GlucoCEST could represent a valid alternative to FDG-PET for tumor diagnosis and staging, still several limitations, including reduced detectability at low field and origin of the glucose-based contrast arising from different compartments need to be tackled in the next years (77).…”