title: Estimation of spinopelvic muscles' volumes in young asymptomatic subjects: a quantitative analysis.
abstract: OBJECTIVE
  Muscles have been proved to be a major component in postural regulation during pathological evolution or aging. Particularly, spinopelvic muscles are recruited for compensatory mechanisms such as pelvic retroversion, or knee flexion. Change in muscles' volume could, therefore, be a marker of greater postural degradation. Yet, it is difficult to interpret spinopelvic muscular degradation as there are few reported values for young asymptomatic adults to compare to. The objective was to provide such reference values on spinopelvic muscles. A model predicting the muscular volume from reduced set of MRI segmented images was investigated.
  
  
  METHODS
  A total of 23 asymptomatic subjects younger than 24 years old underwent an MRI acquisition from T12 to the knee. Spinopelvic muscles were segmented to obtain an accurate 3D reconstruction, allowing precise computation of muscle's volume. A model computing the volume of muscular groups from less than six MRI segmented slices was investigated.
  
  
  RESULTS
  Baseline values have been reported in tables. For all muscles, invariance was found for the shape factor [ratio of volume over (area times length): SD < 0.04] and volume ratio over total volume (SD < 1.2 %). A model computing the muscular volume from a combination of two to five slices has been evaluated. The five-slices model prediction error (in  % of the real volume from 3D reconstruction) ranged from 6 % (knee flexors and extensors and spine flexors) to 11 % (spine extensors).
  
  
  CONCLUSIONS
  Spinopelvic muscles' values for a reference population have been reported. A new model predicting the muscles' volumes from a reduced set of MRI slices is proposed. While this model still needs to be validated on other populations, the current study appears promising for clinical use to determine, quantitatively, the muscular degradation.
authors.affiliation: Arts et Metiers ParisTech, LBM/Institut de Biomécanique Humaine Georges Charpak, 151 Boulevard de l'Hopital, 75013, Paris, France. celia.amabile@ensam.eu.|Spine Service, Hospital for Special Surgery, 535 East 70th Street, Belaire 4-E, New York, NY, 10021, USA. celia.amabile@ensam.eu.
authors.forename: Celia
authors.identifier: http://orcid.org/0000-0003-3307-6581
authors.initials: C
authors.lastname: Amabile
authors.affiliation: Spine Service, Hospital for Special Surgery, 535 East 70th Street, Belaire 4-E, New York, NY, 10021, USA.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Moal
authors.affiliation: Arts et Metiers ParisTech, LBM/Institut de Biomécanique Humaine Georges Charpak, 151 Boulevard de l'Hopital, 75013, Paris, France.
authors.forename: Oussama Arous
authors.initials: OA
authors.lastname: Chtara
authors.affiliation: Arts et Metiers ParisTech, LBM/Institut de Biomécanique Humaine Georges Charpak, 151 Boulevard de l'Hopital, 75013, Paris, France.
authors.forename: Helene
authors.initials: H
authors.lastname: Pillet
authors.affiliation: Center for Biomedical Imaging, Department of Radiology, New York University Langone Medical Center, New York, NY, USA.
authors.forename: Jose G
authors.initials: JG
authors.lastname: Raya
authors.affiliation: Department of Radiology, Centre Antoine Lacassagne, Nice, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Iannessi
authors.affiliation: Arts et Metiers ParisTech, LBM/Institut de Biomécanique Humaine Georges Charpak, 151 Boulevard de l'Hopital, 75013, Paris, France. wafa.skalli@ensam.eu.
authors.forename: Wafa
authors.initials: W
authors.lastname: Skalli
authors.affiliation: Spine Service, Hospital for Special Surgery, 535 East 70th Street, Belaire 4-E, New York, NY, 10021, USA.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
authors.affiliation: Department of Orthopaedic, Trauma, and Spine Surgery, Institut Universitaire de l'appareil Locomoteur et du Sport, Hôpital Pasteur 2, CHU de Nice, Nice, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bronsard
mesh_terms: D000009:Abdominal Muscles / Q000033:anatomy & histology*; D000293:Adolescent; D000328:Adult; D063405:Anatomic Variation; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008953:Models, Anatomic; D008962:Models, Theoretical; D064170:Paraspinal Muscles / Q000033:anatomy & histology*; D010388:Pelvis / Q000033:anatomy & histology*; D011446:Prospective Studies; D012016:Reference Values; D055815:Young Adult
keywords: Asymptomatic subjects; MRI; Muscles; Volume; Young