title: Assessment of coronary plaque collagen with polarization sensitive optical coherence tomography (PS-OCT).
abstract: BACKGROUND
  Current evidence indicates that most plaques classified as vulnerable or ruptured plaque do not lead to unstable angina or myocardial infarction. Improved methods are needed to risk stratify plaques to identify those which lead to most acute coronary syndromes. Collagen depletion in the intima overlying lipid collections appears to be a critical component of unstable plaques. In this study, we use polarization sensitive optical coherence tomography (PS-OCT) for the assessment of coronary plaque collagen. Collagen is birefringent, meaning that different polarization states travel through it at different velocities.
  
  
  RESULTS
  Changes in PS-OCT images are a measure of tissue birefringence. Twenty-two coronary artery segments were imaged with PS-OCT and analyzed by picrosirius staining (a measure of collagen intensity and fiber size) and trichrome blue. The regression plot between PS-OCT changes and measured collagen yielded a correlation coefficient value of 0.475 (p<0.002). The predictive value of a PS-OCT measurement of negligible birefringence (less than 33% change) for minimal collagen was 93% while the predictive value of high birefringence (greater than 66% change) for high collagen concentrations was 89%. The effect of fiber type (chemical composition) was minimal relative to the effect due to fiber concentration.
  
  
  CONCLUSIONS
  The capability of PS-OCT to assess plaque collagen content, in addition to its ability to generate high resolution structural assessments, make it a potentially powerful technology for identifying high risk plaques.
authors.affiliation: Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Susanne D
authors.initials: SD
authors.lastname: Giattina
authors.forename: Brian K
authors.initials: BK
authors.lastname: Courtney
authors.forename: Paul R
authors.initials: PR
authors.lastname: Herz
authors.forename: Michelle
authors.initials: M
authors.lastname: Harman
authors.forename: Sonya
authors.initials: S
authors.lastname: Shortkroff
authors.forename: Debra L
authors.initials: DL
authors.lastname: Stamper
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: James G
authors.initials: JG
authors.lastname: Fujimoto
authors.forename: Mark E
authors.initials: ME
authors.lastname: Brezinski
mesh_terms: D000368:Aged; D001718:Birefringence; D002102:Cadaver; D003094:Collagen / Q000032:analysis*; D003327:Coronary Disease / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D041623:Tomography, Optical Coherence / Q000379:methods*; D017539:Tunica Intima / Q000473:pathology*
chemical_list: D003094:Collagen