title: Post-contractile BOLD contrast in skeletal muscle at 7 T reveals inter-individual heterogeneity in the physiological responses to muscle contraction.
abstract: Muscle blood oxygenation-level dependent (BOLD) contrast is greater in magnitude and potentially more influenced by extravascular BOLD mechanisms at 7 T than it is at lower field strengths. Muscle BOLD imaging of muscle contractions at 7 T could, therefore, provide greater or different contrast than at 3 T. The purpose of this study was to evaluate the feasibility of using BOLD imaging at 7 T to assess the physiological responses to in vivo muscle contractions. Thirteen subjects (four females) performed a series of isometric contractions of the calf muscles while being scanned in a Philips Achieva 7 T human imager. Following 2 s maximal isometric plantarflexion contractions, BOLD signal transients ranging from 0.3 to 7.0% of the pre-contraction signal intensity were observed in the soleus muscle. We observed considerable inter-subject variability in both the magnitude and time course of the muscle BOLD signal. A subset of subjects (n = 7) repeated the contraction protocol at two different repetition times (TR: 1000 and 2500 ms) to determine the potential of T1-related inflow effects on the magnitude of the post-contractile BOLD response. Consistent with previous reports, there was no difference in the magnitude of the responses for the two TRvalues (3.8 ± 0.9 versus 4.0 ± 0.6% for TR= 1000 and 2500 ms, respectively; mean ± standard error). These results demonstrate that studies of the muscle BOLD responses to contractions are feasible at 7 T. Compared with studies at lower field strengths, post-contractile 7 T muscle BOLD contrast may afford greater insight into microvascular function and dysfunction.
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.|Department of Physical Medicine and Rehabilitation, Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.|Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Theodore F
authors.initials: TF
authors.lastname: Towse
authors.affiliation: Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Elder
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.|Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Emily C
authors.initials: EC
authors.lastname: Bush
authors.affiliation: Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Samuel W
authors.initials: SW
authors.lastname: Klockenkemper
authors.affiliation: Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Jared T
authors.initials: JT
authors.lastname: Bullock
authors.affiliation: Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Dortch
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.|Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.|Department of Biomedical Engineering, Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.|Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Damon
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001810:Blood Volume / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen
keywords: MRI; hyperemia; skeletal muscle functional MRI