title: Determination of thigh muscle stiffness using magnetic resonance elastography.
abstract: OBJECTIVE
  To measure the elastic properties of the vastus lateralis (VL), vastus medialis (VM), and sartorius (Sr) muscles using magnetic resonance elastography (MRE).
  
  
  METHODS
  To obtain a normative database of the aforementioned muscles, oblique scan directions were prescribed passing through each muscle. Shear waves were induced into the muscles using pneumatic and mechanical drivers at 90 and 120 Hz, respectively. These drivers were attached to the distal end of the right thigh with the knee flexed at 30 degrees . The foot was placed in a footplate containing MR-compatible load cells to record the force during a contraction (10% and 20% of the maximum voluntary contraction).
  
  
  RESULTS
  The shear moduli measured at rest in the VL (N = 12), VM (N = 14), and Sr (N = 13) were 3.73 +/- 0.85 kPa, 3.91 +/- 1.15 kPa, and 7.53 +/- 1.63 kPa, respectively. The stiffness of both vasti increased with the level of contraction, while the stiffness of the Sr remained the same.
  
  
  CONCLUSIONS
  The MRE technique was able to approximate the stiffness of different thigh muscles. Furthermore, the wave length was sensitive to the morphology (unipennate or longitudinal) and fiber composition (type I or II) in each muscle.
authors.affiliation: Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
authors.forename: Sabine F
authors.initials: SF
authors.lastname: Bensamoun
authors.forename: Stacie I
authors.initials: SI
authors.lastname: Ringleb
authors.forename: Laurel
authors.initials: L
authors.lastname: Littrell
authors.forename: Qingshan
authors.initials: Q
authors.lastname: Chen
authors.forename: Michael
authors.initials: M
authors.lastname: Brennan
authors.forename: Richard L
authors.initials: RL
authors.lastname: Ehman
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004548:Elasticity; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007537:Isometric Contraction / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology; D012016:Reference Values; D012680:Sensitivity and Specificity; D013848:Thigh