title: Assessment of trunk muscle density using CT and its association with degenerative disc and facet joint disease of the lumbar spine.
abstract: OBJECTIVE
  The purpose of this study was (1) to evaluate the association of trunk muscle density assessed by computed tomography (CT) with age, gender, and BMI and (2) to evaluate the association between trunk muscle CT density and degenerative disc and facet joint disease of the lumbar spine.
  
  
  METHODS
  The study was IRB approved and HIPAA compliant. The study group comprised 100 subjects (mean age 44.4 ± 22.2 years, 51 % male) who underwent CT of the abdomen and pelvis without intravenous contrast. Exclusion criteria included prior abdominal or spine surgery, active malignancy and scoliosis. CTs were reviewed and the attenuation of the rectus abdominis, transverse abdominis, internal and external obliques, psoas, multifidus, longissimus and gluteus maximus were measured bilaterally at consistent levels. Degenerative disc and bilateral facet joint disease were scored using established methods. Univariate analyses were performed using linear regression. Multivariate linear regression was performed to adjust for age, gender and BMI.
  
  
  RESULTS
  CT density of each trunk muscle correlated inversely with age (p < 0.001) and BMI (p < 0.001). CT density of each trunk muscle correlated inversely with degenerative disc and facet joint disease in the univariate analyses (p < 0.001); however, only the gluteus maximus and the transverse abdominis remained significant predictors of degenerative disc and facet joint disease respectively in the multivariate analysis.
  
  
  CONCLUSIONS
  Fatty infiltration of trunk musculature increases with age and BMI. Fatty infiltration of the gluteus maximus and transverse abdominis are associated with degenerative disc and facet joint disease, independent of age, gender and BMI.
authors.affiliation: Musculoskeletal Section, Department of Radiology, University of Pennsylvania, 3737 Market Street, No. 6175, Philadelphia, PA, 19104, USA.
authors.forename: Ronnie
authors.initials: R
authors.lastname: Sebro
authors.affiliation: Department of Mathematics and Statistics, Colby College, Waterville, ME, 04901, USA.|School of Community and Population Health, University of New England, Portland, ME, 04103, USA.
authors.forename: Liam
authors.initials: L
authors.lastname: O'Brien
authors.affiliation: Musculoskeletal Imaging and Intervention, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Yawkey 6E, 55 Fruit Street, Boston, MA, 02114, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Torriani
authors.affiliation: Musculoskeletal Imaging and Intervention, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Yawkey 6E, 55 Fruit Street, Boston, MA, 02114, USA. mbredella@mgh.harvard.edu.
authors.forename: Miriam A
authors.initials: MA
authors.lastname: Bredella
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging*; D007592:Joint Diseases / Q000000981:diagnostic imaging*; D008159:Lumbar Vertebrae; D008161:Lumbosacral Region / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D060726:Torso / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: Atrophy; CT; Degenerative disc disease; External oblique; Facet joint disease; Gluteus maximus; Internal oblique; Longissimus; Multifidus; Psoas; Rectus abdominis; Transverse abdominis; Trunk muscle