title: The Depression Index: an objective measure of the severity of pectus excavatum based on vertebral diameter, a morphometric correlate to patient size.
abstract: OBJECTIVE
  In patients with Pectus Excavatum (PEX), the proposed Depression Index (DI) is derived from the absolute measurement of sternal depression using the transverse vertebral body diameter as a surrogate for height. The previously described objective and useful Pectus Index (PI) and Correction Index (CI), utilize thoracic diameters and do not always reflect the severity of the deformity as observed by clinicians.
  
  
  METHODS
  Data for age, weight, height and vertebral diameter of T9, 10 and 11 were collected on 60 patients, with normal skeletons, undergoing CT scanning. The DI, PI and CI were calculated from CT scans on 76 patients with PEX. Indices were also compared to subjective rankings of the deformity from visual inspection of photographs by 5 clinicians.
  
  
  RESULTS
  All parameters of age, weight and height correlated with the vertebral diameter. The DI correlated with the severity of the PEX deformity as also measured by the PI and the CI. There was a better correlation of the observed deformity severity to the DI than the PI or CI.
  
  
  CONCLUSIONS
  There is a strong correlation between transverse vertebral size and patient height. The DI is an objective measurement of the severity of a PEX deformity that is independent of the thoracic diameters.
authors.affiliation: Department of Surgery, Penn State Milton S. Hershey Medical Center, Hershey, PA. Electronic address: kfagelman@hmc.psu.edu.
authors.forename: Kerry M
authors.initials: KM
authors.lastname: Fagelman
authors.affiliation: Department of Radiology, Penn State Milton S. Hershey Medical Center, Hershey, PA.
authors.forename: Sosamma
authors.initials: S
authors.lastname: Methratta
authors.affiliation: Department of Surgery, Penn State Milton S. Hershey Medical Center, Hershey, PA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Cilley
authors.affiliation: Department of Surgery, Penn State Milton S. Hershey Medical Center, Hershey, PA.
authors.forename: Matthew Z
authors.initials: MZ
authors.lastname: Wilson
authors.affiliation: Department of Public Health Sciences, Penn State College of Medicine, Hershey, PA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Hollenbeak
mesh_terms: D000367:Age Factors; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D001827:Body Height; D001835:Body Weight; D005260:Female; D005660:Funnel Chest / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D009929:Organ Size; D013249:Sternum / Q000000981:diagnostic imaging*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging*; D035441:Thoracic Wall / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed
keywords: Correction Index; Depression Index; Pectus Index; Pectus excavatum; Vertebral diameter