In addition to spectroscopy, the increased spectral dispersion also benefits magnetization transfer techniques such as Chemical Exchange Saturation Transfer (CEST) imaging, leading to a high selectivity [Bruker CEST]. Further advantages of chemical exchange techniques at UHF include the higher saturation which can be achieved [Bruker CEST] and a reduction of the exchange rate relative to the chemical shift [Chung 2017]. As the exchange rate must be smaller than the chemical shift, the increased spectral dispersion allows for faster exchanging compounds to be detected [Wu 2016].
A recent paper from Chung et al. demonstrated a significantly increased chemical exchange effect for the amine proton signal in rat brain at 15.2 Tesla compared to 9.4 Tesla. An increase of 65% compared to 9.4 Tesla was reported emphasizing the importance of UHF for chemical exchange applications [Wu 2016, Bruker fMRI]. The same group also investigated phosphocreatine (PCr) modulation with PCrCEST in the hindlimb of mice and found a 29% higher PCrCEST signal at 15.2 Tesla than at 9.4 Tesla. The significant sensitivity of PCrCEST in hindlimb indicates that PCrCEST could be valuable for mapping energy metabolism in muscles such as the heart [Chung 2019].
A prominent CEST application which benefits from UHF is GluCEST, which monitors local metabolic defects in neurodegenerative diseases [Bruker CEST, Pépin 2016]. For example, GluCEST was identified in the past to be a potential in vivo biomarker of Huntington’s disease when applied in a knock-in mouse model using UHF [Pépin 2016], and has recently been used in a mouse epilepsy model, in which chronically methionine sulfoximine (MSO)-seizure-inducing treated mice showed reduced GluCEST contrast in the hippocampus [Bagga 2019].
Furthermore, there are indications that glucoCEST can be used to investigate metabolism associated with neuronal activity. GlucoCEST performed at 17.2 Tesla using a rat model of electrical forepaw stimulation showed negative contrast during stimulation in the same regions that BOLD imaging provided positive contrast, thus demonstrating the ability of CEST fMRI to locally monitor temporal changes of glucose concentration [Roussel 2019].
 Metabolic Imaging in Neurodegenerative Disease using CEST MRI | Bruker: www.bruker.com/service/education-training/webinars/pci-webinars
 Chung JJ, Choi W, Jin T, Lee JH, Kim S-G. Chemical-exchange-sensitive MRI of amide, amine and NOE at 9.4 T versus 15.2 T. NMR in Biomedicine. 2017;30:e3740. doi.org/10.1002/nbm.3740
 Wu B, Warnock G, Zaiss M, Lin C, Chen M, Zhou Z, Mu L, Nanz D, Tuura R, Delso G. An overview of CEST MRI for non-MR physicists. 2016; EJNMMI Physics 3:19www.ncbi.nlm.nih.gov/pubmed/27562024
 New insights into brain function with molecular and functional MRI of the rodent brain at ultra-high fields | Bruker: www.bruker.com/service/education-training/webinars/pci-webinars
 Chung JJ, Jin T, Lee JH, Kim SG. Chemical exchange saturation transfer imaging of phosphocreatine in the muscle. Magnetic Resonance in Medicine 2019, 81(6):3476-3487. doi: 10.1002/mrm.27655
 Pépin J, Francelle L, Carrillo-de Sauvage M-A, de Longprez L, Gipchtein P, Cambon K, Valette J, Brouillet E, Flament J. In vivo imaging of brain glutamate defects in a knock-in mouse model of Huntington's disease. Neuroimage. 2016; 139: 53–64. doi: 10.1016/j.neuroimage.2016.06.023
 Bagga P, Pickup S, Flament J, Detre J, Hariharan H, Reddy R. Mapping astroglial glutamine synthetase activity in vivo in a preclinical model of epilepsy using glutamate-weighted CEST (GluCEST) MRI. ISMRM 2019 3121
 Roussel T, Frydman L, Le Bihan D, Ciobanu L. Brain sugar consumption during neuronal activation detected by CEST functional MRI at ultra-high magnetic fields. Scientific Reports 9(1):4423. doi.org/10.1038/s41598-019-40986-9 1