Magnetic Resonance Fingerprinting for Glutamate Quantification: Towards the Intermediate Exchange Regime

Motivation: Glutamate plays a fundamental role in glioblastoma progression, phenotype, and treatment response. High-resolution, quantitative glutamate imaging at 3T may improve patient outcomes. Goal(s): We sought to improve brain glutamate quantification using chemical exchange saturation transfer (CEST), which provides high spatial resolution but cannot currently work at 3T. Approach: We used magnetic resonance fingerprinting (MRF) incorporating amine CEST and water-resonant spin-locking (CESL) for high contrast and amine specificity. We performed phantom imaging with glutamate concentrations of 5-20 mM at room temperature and pH 7. Results: wrCESL increased image contrast and significantly improved concentration quantification at high-field (9.4T) and closer to clinical field strength (4.7T). Impact: We demonstrate the initial development of quantitative glutamate imaging using chemical exchange and fingerprinting, which offers higher spatial resolution than spectroscopy and can track disease-dependent glutamate changes in the brain, such as for cancer or neurodegeneration.