title: Measurement of Retinal Vascular Caliber From Optical Coherence Tomography Phase Images.
abstract: To compare retinal vessel calibers extracted from phase-sensitive optical coherence tomography (OCT) images with vessel calibers as obtained from the Retinal Vessel Analyzer (RVA).
  
  
  
  Data from previously published studies in 13 healthy subjects breathing room air (n = 214 vessels) and 7 subjects breathing 100% oxygen (n = 101 vessels) were used. Vessel calibers from OCT phase images were measured vertically along the optical axis by three independent graders. The data from RVA fundus images were corrected for magnification to obtain absolute values.
  
  
  
  The average vessel diameter as obtained from OCT images during normoxia was lower than from RVA images (83.8 ± 28.2 μm versus 86.6 ± 28.0 μm, P < 0.001). The same phenomenon was observed during 100% oxygen breathing (OCT: 81.0 ± 22.4 μm, RVA: 85.5 ± 26.0 μm; P = 0.001). Although the agreement between the two methods was generally high, the difference in individual vessels could be as high as 40%. These differences were neither dependent on absolute vessel size nor preferably found in specific subjects. Interobserver differences between OCT evaluators were much lower than differences between the techniques.
  
  
  
  Extracting vessel calibers from OCT phase images may be an attractive approach to overcome some of the problems associated with fundus imaging. The source of differences in vessel caliber between the two methods remains to be investigated. In addition, it remains unclear whether OCT-based vessel caliber measurement is superior to fundus camera-based imaging in risk stratification for systemic or ocular disease. (ClinicalTrials.gov numbers, NCT00914407, NCT02531399.).
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Klemens
authors.initials: K
authors.lastname: Fondi
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria 3Institute of Applied Physics, Vienna University of Technology, Vienna, Austria.
authors.forename: Gerold C
authors.initials: GC
authors.lastname: Aschinger
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Bata
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Piotr A
authors.initials: PA
authors.lastname: Wozniak
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Liang
authors.initials: L
authors.lastname: Liao
authors.affiliation: Department of Ophthalmology, Medical University of Graz, Graz, Austria.
authors.forename: Gerald
authors.initials: G
authors.lastname: Seidel
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria 3Institute of Applied Physics, Vienna University of Technology, Vienna, Austria.
authors.forename: Veronika
authors.initials: V
authors.lastname: Doblhoff-Dier
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria 2Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Doreen
authors.initials: D
authors.lastname: Schmidl
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhöfer
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: René M
authors.initials: RM
authors.lastname: Werkmeister
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria 2Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
mesh_terms: D005260:Female; D005451:Fluorescein Angiography / Q000379:methods*; D005654:Fundus Oculi; D064368:Healthy Volunteers; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D010781:Photography; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012161:Retinal Artery / Q000000981:diagnostic imaging*; D012169:Retinal Vein / Q000000981:diagnostic imaging*; D041623:Tomography, Optical Coherence / Q000379:methods*