title: Office-based elastographic technique for quantifying mechanical properties of skeletal muscle.
abstract: OBJECTIVE
  Our objectives were to develop a new, efficient, and easy-to-administer approach to ultrasound elastography and assess its ability to provide quantitative characterization of viscoelastic properties of skeletal muscle in an outpatient clinical environment. We sought to show its validity and clinical utility in assessing myofascial trigger points, which are associated with myofascial pain syndrome.
  
  
  METHODS
  Ultrasound imaging was performed while the muscle was externally vibrated at frequencies in the range of 60 to 200 Hz using a handheld vibrator. The spatial gradient of the vibration phase yielded the shear wave speed, which is related to the viscoelastic properties of tissue. The method was validated using a calibrated experimental phantom, the biceps brachii muscle in healthy volunteers (n = 6), and the upper trapezius muscle in symptomatic patients with axial neck pain (n = 13) and asymptomatic (pain-free) control participants (n = 9).
  
  
  RESULTS
  Using the experimental phantom, our method was able to quantitatively measure the shear moduli with error rates of less than 20%. The mean shear modulus ± SD in the normal biceps brachii measured 12.5 ± 3.4 kPa, within the range of published values using more sophisticated methods. Shear wave speeds in active myofascial trigger points and the surrounding muscle tissue were significantly higher than those in normal tissue at high frequency excitations (>100 Hz; P < .05).
  
  
  CONCLUSIONS
  Off-the-shelf office-based equipment can be used to quantitatively characterize skeletal muscle viscoelastic properties with estimates comparable to those using more sophisticated methods. Our preliminary results using this method indicate that patients with spontaneous neck pain and symptomatic myofascial trigger points have increased tissue heterogeneity at the trigger point site and the surrounding muscle tissue.
authors: Department of Electrical and Computer Engineering, George Mason University, Fairfax, Virginia 22030, USA.
authors: Jeffrey J
authors: JJ
authors: Ballyns
authors: Diego
authors: D
authors: Turo
authors: Paul
authors: P
authors: Otto
authors: Jay P
authors: JP
authors: Shah
authors: Jennifer
authors: J
authors: Hammond
authors: Tadesse
authors: T
authors: Gebreab
authors: Lynn H
authors: LH
authors: Gerber
authors: Siddhartha
authors: S
authors: Sikdar
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D054459:Elasticity Imaging Techniques / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D009209:Myofascial Pain Syndromes / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D019047:Phantoms, Imaging; D010808:Physical Examination; D012815:Signal Processing, Computer-Assisted