title: Differences in fatty degeneration of rotator cuff muscles at different sites, as quantified by T2 mapping.
abstract: BACKGROUND
  Fatty degeneration of the cuff muscles is usually evaluated at the Y-view in oblique sagittal images. It was recently proposed that muscle shift after repair may influence the fatty degeneration values, and the evaluation of the muscles at a more medial site was recommended. However, the differences in muscle quality in accord with measurement sites have been unclear. Here we evaluated differences in fatty degeneration of the rotator cuff muscles measured quantitatively at different sites, using T2 mapping.
  
  
  METHODS
  We assessed 702 shoulders of 675 patients (335 males, 340 females; mean age, 62 years) who underwent MRI including T2 mapping. There were 345 shoulders without rotator cuff tears and 357 shoulders with tears: partial tear = 103 shoulders; small = 63; medium = 94; large = 71; massive = 26. T2 values of the supraspinatus and infraspinatus muscles were measured on the Y-view and on the image that was 15 mm medial to the Y-view.
  
  
  RESULTS
  The T2 values at the medial site increased with the tear extent, as did those on the Y-view. There were no significant differences in supraspinatus T2 values between those on the Y-view and at the medial site in all tear size groups except medium and large tears (p = 0.008 and p < 0.001, respectively). There were also no significant differences in infraspinatus T2 values between the two sites in all tear size groups except large tears (p = 0.002). However, the differences were relatively small (2.4-5.6 ms), which were within the standard deviations of the measurements.
  
  
  CONCLUSIONS
  The T2 values of the supraspinatus and infraspinatus muscles on the Y-view and at 15 mm medial to it were almost identical, with the exception of small differences in the case of larger tears.
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan. Electronic address: y-jima@omiya.jichi.ac.jp.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Iijima
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsuki
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Hoshika
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ueda
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan.
authors.forename: Kazutomo
authors.initials: K
authors.lastname: Onishi
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan.
authors.forename: Morihito
authors.initials: M
authors.lastname: Tokai
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan.
authors.forename: Norimasa
authors.initials: N
authors.lastname: Takahashi
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sugaya
authors.affiliation: Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba, 2740822, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Dougo
authors.affiliation: Department of Orthopaedic Surgery, Eastern Chiba Medical Center, 3-6-2 Okayamadai, Togane, Chiba, 2838686, Japan.
authors.forename: Atsuya
authors.initials: A
authors.lastname: Watanabe
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015601:Injury Severity Score; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology; D012189:Retrospective Studies; D000070636:Rotator Cuff Injuries / Q000000981:diagnostic imaging* / Q000473:pathology*; D020069:Shoulder Pain / Q000175:diagnosis / Q000209:etiology