title: Fatty degeneration of the rotator cuff muscles on pre- and postoperative CT arthrography (CTA): is the Goutallier grading system reliable?
abstract: OBJECTIVE
  To retrospectively evaluate fatty degeneration (FD) of rotator cuff muscles on CTA using Goutallier's grading system and quantitative measurements with comparison between pre- and postoperative states.
  
  
  METHODS
  IRB approval was obtained for this study. Two radiologists independently reviewed pre- and postoperative CTAs of 43 patients (24 males and 19 females, mean age, 58.1 years) with 46 shoulders confirmed as full-thickness tears with random distribution. FD of supraspinatus, infraspinatus/teres minor, and subscapularis was assessed using Goutallier's system and by quantitative measurements of Hounsfield units (HUs) on sagittal images. Changes in FD grades and HUs were compared between pre- and postoperative CTAs and analyzed with respect to preoperative tear size and postoperative cuff integrity. The correlations between qualitative grades and quantitative measurements and their inter-observer reliabilities were also assessed.
  
  
  RESULTS
  There was statistically significant correlation between FD grades and HU measurements of all muscles on pre- and postoperative CTA (p < 0.05). Inter-observer reliability of fatty degeneration grades were excellent to substantial on both pre- and postoperative CTA in supraspinatus (0.8685 and 0.8535) and subscapularis muscles (0.7777 and 0.7972), but fair in infraspinatus/teres minor muscles (0.5791 and 0.5740); however, quantitative Hounsfield units measurements showed excellent reliability for all muscles (ICC: 0.7950 and 0.9346 for SST, 0.7922 and 0.8492 for SSC, and 0.9254 and 0.9052 for IST/TM). No muscle showed improvement of fatty degeneration after surgical repair on qualitative and quantitative assessments; there was no difference in changes of fatty degeneration after surgical repair according to preoperative tear size and post-operative cuff integrity (p > 0.05). The average dose-length product (DLP, mGy · cm) was 365.2 mGy · cm (range, 323.8-417.2 mGy · cm) and estimated average effective dose was 5.1 mSv.
  
  
  CONCLUSIONS
  Goutallier grades correlated well with HUs of rotator cuff muscles. Reliability was excellent for both systems, except for FD grade of IST/TM muscles, which may be more reliably assessed using quantitative measurements.
authors.affiliation: Department of Radiology, Seoul National University Bundang Hospital, 166, Gumi-ro, Bundang-Gu, Seongnam-si, Gyeongi-do 463-707, Republic of Korea. eugene801027@gmail.com
authors.forename: Eugene
authors.initials: E
authors.lastname: Lee
authors.forename: Jung-Ah
authors.initials: JA
authors.lastname: Choi
authors.forename: Joo Han
authors.initials: JH
authors.lastname: Oh
authors.forename: Soyeon
authors.initials: S
authors.lastname: Ahn
authors.forename: Sung Hwan
authors.initials: SH
authors.lastname: Hong
authors.forename: Jee Won
authors.initials: JW
authors.lastname: Chai
authors.forename: Heung Sik
authors.initials: HS
authors.lastname: Kang
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D001175:Arthrography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009133:Muscular Atrophy / Q000000981:diagnostic imaging* / Q000209:etiology; D015588:Observer Variation; D011300:Preoperative Care; D011379:Prognosis; D019651:Plastic Surgery Procedures / Q000009:adverse effects*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000000981:diagnostic imaging* / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome