title: Magnetic resonance elastography (MRE) for measurement of muscle stiffness of the shoulder: feasibility with a 3 T MRI system.
abstract: BACKGROUND
  Magnetic resonance elastography (MRE) at 3 T MR has the potential to improve the objective detection of skeletal muscle stiffness.
  
  
  OBJECTIVE
  To determine the feasibility of MRE using 3 T MR for measurement of the stiffness of shoulder muscles in subjects.
  
  
  METHODS
  This study prospectively evaluated 16 healthy subjects (mean age, 29.8 years; range, 25-51 years). MRE was acquired with 3 T MR through the use of a 2D-gradient-echo-based MRE sequence at two different excitation frequencies (90 and 120 Hz). The mean stiffness values (MSV) of the trapezius and infraspinatus muscles were measured by two radiologists. Differences between the MSV in the x, y, and z motion-sensitization directions were assessed. Inter-observer agreement was also measured.
  
  
  RESULTS
  The MSV of the trapezius muscle were 2.72 kPa ± 0.6 (SD) at 90 Hz and 4.66 kPa ± 1.2 at 120 Hz, while the MSV for the infraspinatus muscle were 3.2 kPa ± 0.52 at 90 Hz and 4.38 kPa ± 0.92 at 120 Hz. The MSV for both muscles were significantly higher at 120 Hz than at 90 Hz (P < 0.05). The MSV in the three different directions were significantly different from each other in the infraspinatus muscle (P < 0.05). Levels of inter-observer agreement regarding MSV were good to excellent for both the trapezius (intraclass correlation coefficient [ICC] = 0.979-0.996) and infraspinatus muscles (ICC = 0.614-0.943).
  
  
  CONCLUSIONS
  MRE at 3 T is a feasible technique for the evaluation of shoulder muscle stiffness. Extended application of skeletal muscle MRE at 3 T will contribute to the evaluation and treatment of skeletal muscle disorders.
authors.affiliation: Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sun Hwa
authors.initials: SH
authors.lastname: Hong
authors.affiliation: Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea hongsj@korea.ac.kr.
authors.forename: Suk-Joo
authors.initials: SJ
authors.lastname: Hong
authors.affiliation: Department of Rehabilitation Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Joon-Shik
authors.initials: JS
authors.lastname: Yoon
authors.affiliation: Department of Electronics & Information Engineering and Korea Artificial Organ Center, Korea University, Seoul, Republic of Korea.
authors.forename: Chang-Hyun
authors.initials: CH
authors.lastname: Oh
authors.affiliation: Department of Radiology, Soonchunhyang University Bucheon Hospital, Bucheon-Si, Republic of Korea.
authors.forename: Jang Gyu
authors.initials: JG
authors.lastname: Cha
authors.affiliation: Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Kim
authors.affiliation: Siemens Healthcare, USA, Inc., Malvern, PA, USA.
authors.forename: Bradley
authors.initials: B
authors.lastname: Bolster
mesh_terms: D000328:Adult; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011446:Prospective Studies; D012782:Shoulder / Q000000981:diagnostic imaging* / Q000503:physiopathology*
keywords: 3 Tesla; Magnetic resonance elastography (MRE); shoulder; skeletal muscle