title: Perfusion has no effect on the in vivo CEST effect from Cr (CrCEST) in skeletal muscle.
abstract: Creatine, a key component of muscle energy metabolism, exhibits a chemical exchange saturation transfer (CEST) effect between its amine group and bulk water, which has been exploited to spatially and temporally map creatine changes in skeletal muscle before and after exercise. In addition, exercise leads to an increase in muscle perfusion. In this work, we determined the effects of perfused blood on the CEST effects from creatine in skeletal muscle. Experiments were performed on healthy human subjects (n = 5) on a whole-body Siemens 7T magnetic resonance imaging (MRI) scanner with a 28-channel radiofrequency (RF) coil. Reactive hyperemia, induced by inflation and subsequent deflation of a pressure cuff secured around the thigh, was used to increase tissue perfusion whilst maintaining the levels of creatine kinase metabolites. CEST, arterial spin labeling (ASL) and31P MRS data were acquired at baseline and for 6 min after cuff deflation. Reactive hyperemia resulted in substantial increases in perfusion in human skeletal muscle of the lower leg as measured by the ASL mean percentage difference. However, no significant changes in CrCEST asymmetry (CrCESTasym) or31P MRS-derived PCr levels of skeletal muscle were observed following cuff deflation. This work demonstrates that perfusion changes do not have a major confounding effect on CrCEST measurements.
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Feliks
authors.initials: F
authors.lastname: Kogan
authors.affiliation: Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Randall B
authors.initials: RB
authors.lastname: Stafford
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Erin K
authors.initials: EK
authors.lastname: Englund
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Garry E
authors.initials: GE
authors.lastname: Gold
authors.affiliation: Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Hari
authors.initials: H
authors.lastname: Hariharan
authors.affiliation: Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.|Center for Functional Neuroimaging, University of Pennsylvania, Philadelphia, Pennsylvania, USA.|Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
authors.affiliation: Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Ravinder
authors.initials: R
authors.lastname: Reddy
mesh_terms: D000328:Adult; D000465:Algorithms; D001783:Blood Flow Velocity / Q000502:physiology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; 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*; D010725:Phosphocreatine / Q000378:metabolism*; D010758:Phosphorus / Q000493:pharmacokinetics; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D010725:Phosphocreatine; D010758:Phosphorus
keywords: ASL; CEST; CrCEST; creatine; energy metabolism; muscle; perfusion