title: The etiology of pectus carinatum involves overgrowth of costal cartilage and undergrowth of ribs.
abstract: OBJECTIVE
  We compared the length of costal cartilage and rib between patients with symmetric pectus carinatum and controls without anterior chest wall protrusion, using a 3-dimensional (3D) computed tomography (CT) to evaluate whether the overgrowth of costal cartilage exists in patients with pectus carinatum.
  
  
  METHODS
  Twenty-six patients with symmetric pectus carinatum and matched twenty-six controls without chest wall protrusion were enrolled. We measured the full lengths of the 4th-6th ribs and costal cartilages using 3-D volume rendering CT images and the curved multiplanar reformatted (MPR) techniques. The lengths of ribs and costal cartilages, the summation of rib and costal cartilage lengths, and the costal index [length of cartilage/length of rib * 100 (%)] were compared between the patients group and the control group at 4th-6th levels.
  
  
  RESULTS
  The lengths of costal cartilage in patient group were significantly longer than those of control group at 4th, 5th and 6th rib level. The lengths of ribs in patient group were significantly shorter than those of control group at 4th, 5th and 6th rib level. The summations of rib and costal cartilage lengths were not longer in patients group than in control group. The costal indices were significantly larger in patients group than in control groups at 4th, 5th and 6th rib level.
  
  
  CONCLUSIONS
  In patients with symmetric pectus carinatum, the lengths of costal cartilage were longer but the lengths of rib were shorter than those of controls. These findings may supports that the overgrowth of costal cartilage was not the only factor responsible for pectus carinatum.
authors.affiliation: Department of Radiology and the Research Institute of Radiological Science, Yonsei University Health System, Seoul, Republic of Korea.
authors.forename: Chul Hwan
authors.initials: CH
authors.lastname: Park
authors.affiliation: Department of Radiology and the Research Institute of Radiological Science, Yonsei University Health System, Seoul, Republic of Korea.
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Seok Jin
authors.initials: SJ
authors.lastname: Haam
authors.affiliation: Department of Radiology and the Research Institute of Radiological Science, Yonsei University Health System, Seoul, Republic of Korea.
authors.forename: Inhwan
authors.initials: I
authors.lastname: Jeon
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea. Electronic address: chestlee@yuhs.ac.
authors.forename: Sungsoo
authors.initials: S
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D066186:Costal Cartilage / Q000000981:diagnostic imaging / Q000254:growth & development*; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D066166:Pectus Carinatum / Q000000981:diagnostic imaging / Q000209:etiology*; D012189:Retrospective Studies; D012272:Ribs / Q000000981:diagnostic imaging / Q000254:growth & development*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: 3-dimensional computed tomography; Costal cartilage; Pectus carinatum; Rib