title: Magnetization exchange observed in human skeletal muscle by non-water-suppressed proton magnetic resonance spectroscopy.
abstract: Many metabolites in the proton magnetic resonance spectrum undergo magnetization exchange with water, such as those in the downfield region (6.0-8.5 ppm) and the upfield peaks of creatine, which can be measured to reveal additional information about the molecular environment. In addition, these resonances are attenuated by conventional water suppression techniques complicating detection and quantification. To characterize these metabolites in human skeletal muscle in vivo at 3 T, metabolite cycled non-water-suppressed spectroscopy was used to conduct a water inversion transfer experiment in both the soleus and tibialis anterior muscles. Resulting median exchange-independent T1 times for the creatine methylene resonances were 1.26 and 1.15 s, and for the methyl resonances were 1.57 and 1.74 s, for soleus and tibialis anterior muscles, respectively. Magnetization transfer rates from water to the creatine methylene resonances were 0.56 and 0.28 s(-1), and for the methyl resonances were 0.39 and 0.30 s(-1), with the soleus exhibiting faster transfer rates for both resonances, allowing speculation about possible influences of either muscle fibre orientation or muscle composition on the magnetization transfer process. These water magnetization transfer rates observed without water suppression are in good agreement with earlier reports that used either postexcitation water suppression in rats, or short CHESS sequences in human brain and skeletal muscle.
authors.affiliation: Department of Clinical Research and Institute of Diagnostic, Interventional and Pediatric Radiology, University of Bern, Bern, Switzerland.
authors.forename: Erin L
authors.initials: EL
authors.lastname: MacMillan
authors.forename: Chris
authors.initials: C
authors.lastname: Boesch
authors.forename: Roland
authors.initials: R
authors.lastname: Kreis
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001834:Body Water / Q000378:metabolism*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D060526:Magnetic Fields; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008875:Middle Aged; D008954:Models, Biological; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D011522:Protons; D055815:Young Adult
chemical_list: D009124:Muscle Proteins; D011522:Protons