title: Spectral oximetry assessed with high-speed ultra-high-resolution optical coherence tomography.
abstract: We use Fourier domain optical coherence tomography (OCT) data to assess retinal blood oxygen saturation. Three-dimensional disk-centered retinal tissue volumes were assessed in 17 normal healthy subjects. After removing DC and low-frequency a-scan components, an OCT fundus image was created by integrating total reflectance into a single reflectance value. Thirty fringe patterns were sampled; 10 each from the edge of an artery, adjacent tissue, and the edge of a vein, respectively. A-scans were recalculated, zeroing the DC term in the power spectrum, and used for analysis. Optical density ratios (ODRs) were calculated as ODR(Art)=ln(Tissue(855)Art(855))ln(Tissue(805)Art(805)) and ODR(Vein)=ln(Tissue(855)Vein(855))ln(Tissue(805)Vein(805)) with Tissue, Art, and Vein representing total a-scan reflectance at the 805- or 855-nm centered bandwidth. Arterial and venous ODRs were compared by the Wilcoxon signed rank test. Arterial ODRs were significantly greater than venous ODRs (1.007+/-2.611 and -1.434+/-4.310, respectively; p=0.0217) (mean+/-standard deviation). A difference between arterial and venous blood saturation was detected. This suggests that retinal oximetry may possibly be added as a metabolic measurement in structural imaging devices.
authors.affiliation: University of Pittsburgh School of Medicine, Department of Ophthalmology, Ophthalmology and Visual Sciences Research Center, UPMC Eye Center, Eye and Ear Institute, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Larry
authors.initials: L
authors.lastname: Kagemann
authors.forename: Gadi
authors.initials: G
authors.lastname: Wollstein
authors.forename: Maciej
authors.initials: M
authors.lastname: Wojtkowski
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Townsend
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Gabriele
authors.forename: Vivek J
authors.initials: VJ
authors.lastname: Srinivasan
authors.forename: James G
authors.initials: JG
authors.lastname: Fujimoto
authors.forename: Joel S
authors.initials: JS
authors.lastname: Schuman
mesh_terms: D000465:Algorithms; D001783:Blood Flow Velocity / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D010092:Oximetry / Q000379:methods*; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000033:anatomy & histology / Q000502:physiology*; D042262:Retinoscopy / Q000379:methods*; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000379:methods*