title: Visual MRI grading system to evaluate atrophy of the supraspinatus muscle.
abstract: OBJECTIVE
  To investigate the interobserver reproducibility and diagnostic feasibility of a visual grading system for assessing atrophy of the supraspinatus muscle on magnetic resonance imaging (MRI).
  
  
  METHODS
  Three independent radiologists retrospectively evaluated the occupying ratio of the supraspinatus muscle in the supraspinatus fossa on 192 shoulder MRI examinations in 188 patients using a 3-point visual grading system (1, ≥ 60%; 2, 30-59%; 3, < 30%) on oblique sagittal T1-weighted images. The inter-reader agreement and the agreement with the reference standard (3-point grades according to absolute occupying ratio values quantitatively measured by directly contouring the muscles on MRI) were analyzed using weighted kappa. The visual grading was applied by a single reader to a group of 100 consecutive patients who had undergone rotator cuff repair to retrospectively determine the association between the visual grades at preoperative state and postsurgical occurrences of retear.
  
  
  RESULTS
  The inter-reader weighted kappa value for the visual grading was 0.74 when averaged across three reader pairs (0.70-0.77 for individual reader pairs). The weighted kappa value between the visual grading and the reference standard ranged from 0.75 to 0.83. There was a significant difference in retear rates of the rotator cuff between the 3 visual grades of supraspinatus muscle atrophy on MRI in univariable analysis (p < 0.001), but not in multivariable analysis (p = 0.026).
  
  
  CONCLUSIONS
  The 3-point visual grading system may be a feasible method to assess the severity of supraspinatus muscle atrophy on MRI and assist in the clinical management of patients with rotator cuff tear.
authors: Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea. ; Department of Radiology, SMG-SNU Boramae Medical Center, Seoul 156-707, Korea.
authors: Hyun Kyong
authors: HK
authors: Lim
authors: Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors: Sung Hwan
authors: SH
authors: Hong
authors: Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors: Hye Jin
authors: HJ
authors: Yoo
authors: Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors: Ja-Young
authors: JY
authors: Choi
authors: Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors: Sae Hoon
authors: SH
authors: Kim
authors: Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors: Jung-Ah
authors: JA
authors: Choi
authors: Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors: Heung Sik
authors: HS
authors: Kang
mesh_terms: D000328:Adult; D000368:Aged; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007592:Joint Diseases; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009133:Muscular Atrophy / Q000175:diagnosis / Q000473:pathology*; D015588:Observer Variation; D012015:Reference Standards; D015203:Reproducibility of Results; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000473:pathology*; D055815:Young Adult
keywords: Magnetic resonance imaging; Muscular atrophy; Occupation ratio; Rotator cuff tear; Supraspinatus muscle