title: Correlation of collagen organization with polarization sensitive imaging of in vitro cartilage: implications for osteoarthritis.
abstract: OBJECTIVE
  Optical coherence tomography (OCT), a new method of high resolution imaging, has shown feasibility for assessing articular cartilage to identify early changes in osteoarthritis (OA) and monitor therapy. OCT is analogous to ultrasound, measuring the intensity of backreflected infrared light rather than sound. The resolution of this technology is up to 25 times higher than existing methods. We investigated the correlation between changes observed by OCT and the degree of collagen organization in OA cartilage.
  
  
  METHODS
  Polarization sensitive OCT (PSOCT) imaging was used to assess changes in cartilage collagen organization in vitro.
  
  
  RESULTS
  The presence (or absence) of PSOCT changes correlated with collagen organization (or disorganization) on histology as assessed by picrosirius polarization microscopy (no significant difference). In multiple cases, cartilage was abnormal by both PSOCT and polarization microscopy, but was grossly normal by routine staining, showing cartilage thickness > 2 mm and no fibrillations.
  
  
  CONCLUSIONS
  This in vitro study suggests PSOCT changes in cartilage are due to the state of collagen organization. The combination of high resolution structural imaging and birefringence detection make OCT a potentially powerful technology for early assessment of OA.
authors.affiliation: Division of Orthopedic Surgery, Harvard Medical School, Brigham and Women's Hospital, Boston, USA.
authors.forename: W
authors.initials: W
authors.lastname: Drexler
authors.forename: D
authors.initials: D
authors.lastname: Stamper
authors.forename: C
authors.initials: C
authors.lastname: Jesser
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: C
authors.initials: C
authors.lastname: Pitris
authors.forename: K
authors.initials: K
authors.lastname: Saunders
authors.forename: S
authors.initials: S
authors.lastname: Martin
authors.forename: M B
authors.initials: MB
authors.lastname: Lodge
authors.forename: J G
authors.initials: JG
authors.lastname: Fujimoto
authors.forename: M E
authors.initials: ME
authors.lastname: Brezinski
mesh_terms: D002358:Cartilage, Articular / Q000737:chemistry* / Q000473:pathology*; D003094:Collagen / Q000032:analysis*; D006801:Humans; D066298:In Vitro Techniques; D010003:Osteoarthritis / Q000473:pathology*; D014054:Tomography / Q000379:methods*
chemical_list: D003094:Collagen