title: A portable system for the assessment of neuromuscular diseases with electrical impedance myography.
abstract: OBJECTIVE
  To create a system for the acquisition of multi-angle, multifrequency muscle impedance data.
  
  
  METHODS
  Device development and preliminary testing.
  
  
  METHODS
  The system presented here employs an interrogating signal composed of multiple tones with frequencies between 10 kHz and 300 kHz. The use of a composite signal makes possible measurement of impedance at multiple frequencies simultaneously. In addition, this system takes impedance measurements at multiple orientations with respect to the muscle fibres by means of an electronically reconfigurable electrode array. The required measurement time is reduced by taking advantage of muscle's linearity with respect to the flow of electrical current.
  
  
  RESULTS
  The system was tested in normal subjects, a patient with amyotrophic lateral sclerosis, and one with inclusion body myositis; unique impedance signatures were identified the two patients.
  
  
  CONCLUSIONS
  Early data suggest that this system is capable of high-quality data collection and may detect changes in neuromuscular disease; study of additional normal subjects and patients with a variety of neuromuscular diseases is warranted.
authors.affiliation: Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. muyi@mit.edu
authors.forename: O T
authors.initials: OT
authors.lastname: Ogunnika
authors.forename: S B
authors.initials: SB
authors.lastname: Rutkove
authors.forename: H
authors.initials: H
authors.lastname: Ma
authors.forename: P M
authors.initials: PM
authors.lastname: Fogerson
authors.forename: M
authors.initials: M
authors.lastname: Scharfstein
authors.forename: R C
authors.initials: RC
authors.lastname: Cooper
authors.forename: J L
authors.initials: JL
authors.lastname: Dawson
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D016880:Anisotropy; D019295:Computational Biology; D017097:Electric Impedance; D004582:Electronics, Medical / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology / Q000503:physiopathology; D009213:Myography / Q000295:instrumentation* / Q000379:methods; D018979:Myositis, Inclusion Body / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted