title: Ultrasound imaging distinguishes between normal and weak muscle.
abstract: OBJECTIVE
  To determine whether real-time ultrasound imaging can provide quantitative data that distinguish pathologic from healthy muscle and that correlate with strength measures.
  
  
  METHODS
  Nonrandomized matched-pair, repeated-measures design.
  
  
  METHODS
  Ultrasound imaging laboratory, rehabilitation medicine department, government research hospital.
  
  
  METHODS
  Nine patients with stable active or inactive myositis, stratified into 3 groups based on their 10-point manual muscle test (MMT) scores, and 9 age- and gender-matched controls.
  
  
  METHODS
  Maximal isometric contraction of the rectus femoris muscle in 2 knee-flexion positions (60 degrees, 90 degrees ) during simultaneous ultrasound imaging and muscle force dynamometry.
  
  
  METHODS
  Changes of the rectus femoris muscle in horizontal (X) and vertical (Y) diameters between relaxed and contracted states, and muscle force measurements.
  
  
  RESULTS
  The X diameters decreased and the Y diameters increased during isometric contraction in all participants. For each group, average changes in cross-sectional diameters were consistently higher in controls than in patients. Patients with MMT less than 8 differed significantly from controls in both X and Y dimensions. A moderately strong correlation was found between muscle force and the Y diameter during contraction at 60 degrees (r =.78) and 90 degrees (r =.67) knee-flexion angles.
  
  
  CONCLUSIONS
  Ultrasonography provided a quantitative measure of change between relaxed and contracted state of muscle, which correlated with muscle force. Ultrasound identified significant differences in cross-sectional diameters between the myopathic and normal muscles sampled and may be useful for measuring muscle response to drug and exercise therapy.
authors.affiliation: Department of Rehabilitation Medicine, Warren G. Magnuson Clinical Center, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
authors.forename: Gloria
authors.initials: G
authors.lastname: Chi-Fishman
authors.forename: Jeanne E
authors.initials: JE
authors.lastname: Hicks
authors.forename: Holly M
authors.initials: HM
authors.lastname: Cintas
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Sonies
authors.forename: Lynn H
authors.initials: LH
authors.lastname: Gerber
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000000981:diagnostic imaging* / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000473:pathology; D009220:Myositis / Q000000981:diagnostic imaging*; D012044:Regression Analysis; D013848:Thigh; D014463:Ultrasonography