title: Time-resolved phosphorous magnetization transfer of the human calf muscle at 3 T and 7 T: a feasibility study.
abstract: Phosphorous ((31)P) magnetization transfer (MT) experiments enable the non-invasive investigation of human muscle metabolism in various physiological and pathological conditions. The purpose of our study was to investigate the feasibility of time-resolved MT, and to compare the results of MT experiments at 3 T and 7 T. Six healthy volunteers were examined on a 3T and a 7 T MR scanner using the same setup and identical measurement protocols. In the calf muscle of all volunteers, four separate MT experiments (each ∼10 min duration) were performed in one session. The forward rate constant of the ATP synthesis reaction (kATP) and creatine kinase reaction (kCK), as well as corresponding metabolic fluxes (FATP, FCK), were estimated. A comparison of these exchange parameters, apparent T₁s, data quality, quantification precision, and reproducibility was performed. The data quality and reproducibility of the same MT experiments at 7 T was significantly higher (i.e., kATP 2.7 times higher and kCK 3.4 times higher) than at 3 T (p<0.05). The values for kATP (p=0.35) and kCK (p=0.09) at both field strengths were indistinguishable. Even a single MT experiment at 7 T provided better data quality than did a 4 times-longer MT experiment at 3T. The minimal time-resolution to reliably quantify both FATP and FCK at 7 T was ∼6 min. Our results show that MT experiments at 7 T can be at least 4 times faster than 3 T MT experiments and still provide significantly better quantification. This enables time-resolved MT experiments for the observation of slow metabolic changes in the human calf muscle at 7 T.
authors.affiliation: MR Center of Excellence, Department of Radiology, Medical University Vienna, A-1090 Wien, Lazarettgasse 14, Austria.
authors.forename: Ladislav
authors.initials: L
authors.lastname: Valkovič
authors.forename: Marek
authors.initials: M
authors.lastname: Chmelík
authors.forename: Ivica
authors.initials: I
authors.lastname: Just Kukurova
authors.forename: Martin
authors.initials: M
authors.lastname: Krššák
authors.forename: Stephan
authors.initials: S
authors.lastname: Gruber
authors.forename: Ivan
authors.initials: I
authors.lastname: Frollo
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bogner
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000328:Adult; D003402:Creatine Kinase / Q000378:metabolism*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007866:Leg; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000378:metabolism*; D010759:Phosphorus Isotopes; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010759:Phosphorus Isotopes; D000255:Adenosine Triphosphate; D003402:Creatine Kinase