title: Gold nanorods as a contrast agent for Doppler optical coherence tomography.
abstract: OBJECTIVE
  To investigate gold nanorods (GNRs) as a contrast agent to enhance Doppler optical coherence tomography (OCT) imaging of the intrascleral aqueous humor outflow.
  
  
  METHODS
  A serial dilution of GNRs was scanned with a spectral-domain OCT device (Bioptigen, Durham, NC) to visualize Doppler signal. Doppler measurements using GNRs were validated using a controlled flow system. To demonstrate an application of GNR enhanced Doppler, porcine eyes were perfused at constant pressure with mock aqueous alone or 1.0×10(12) GNR/mL mixed with mock aqueous. Twelve Doppler and volumetric SD-OCT scans were obtained from the limbus in a radial fashion incremented by 30°, forming a circular scan pattern. Volumetric flow was computed by integrating flow inside non-connected vessels throughout all 12 scans around the limbus.
  
  
  RESULTS
  At the GNR concentration of 0.7×10(12) GNRs/mL, Doppler signal was present through the entire depth of the testing tube without substantial attenuation. A well-defined laminar flow profile was observed for Doppler images of GNRs flowing through the glass capillary tube. The Doppler OCT measured flow profile was not statistically different from the expected flow profile based upon an autoregressive moving average model, with an error of -0.025 to 0.037 mm/s (p = 0.6435). Cross-sectional slices demonstrated the ability to view anterior chamber outflow ex-vivo using GNR-enhanced Doppler OCT. Doppler volumetric flow measurements were comparable to flow recorded by the perfusion system.
  
  
  CONCLUSIONS
  GNRs created a measureable Doppler signal within otherwise silent flow fields in OCT Doppler scans. Practical application of this technique was confirmed in a constant pressure ex-vivo aqueous humor outflow model in porcine eyes.
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America; Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Larry
authors.initials: L
authors.lastname: Kagemann
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Joel S
authors.initials: JS
authors.lastname: Schuman
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishikawa
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Medical Scientist Training Program, Carnegie Mellon University and University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Bilonick
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Medical Scientist Training Program, Carnegie Mellon University and University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ling
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Ian A
authors.initials: IA
authors.lastname: Sigal
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Zach
authors.initials: Z
authors.lastname: Nadler
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Andrew
authors.initials: A
authors.lastname: Francis
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Michelle G
authors.initials: MG
authors.lastname: Sandrian
authors.affiliation: UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Gadi
authors.initials: G
authors.lastname: Wollstein
mesh_terms: D000818:Animals; D001082:Aqueous Humor / Q000737:chemistry*; D003287:Contrast Media / Q000737:chemistry*; D004301:Doppler Effect; D005123:Eye / Q000648:ultrastructure*; D006046:Gold / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D012212:Rheology / Q000379:methods*; D013552:Swine; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000379:methods
chemical_list: D003287:Contrast Media; D006046:Gold