May 2005
Volume 46, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2005
Signal Strength Outperformed Signal to Noise Ratio in Evaluating StratusOCT Image Quality
H. Ishikawa; G. Wollstein; H. Ishikawa; M.L. Gabriele; A.A. Bonfioli; R.J. Noecker; D. Greenfield; C. Mattox; R. Varma; J.S. Schuman
Author Affiliations & Notes
  • H. Ishikawa
    UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • G. Wollstein
    UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • H. Ishikawa
    UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • M.L. Gabriele
    UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • A.A. Bonfioli
    UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • R.J. Noecker
    UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • D. Greenfield
    Bascom Palmer Eye Institute, Miami, FL
  • C. Mattox
    New England Eye Center, Tufts–New England Medical Center, Boston, MA
  • R. Varma
    Doheny Eye Institute, University of Southern California, Los Angeles, CA
  • J.S. Schuman
    UPMC Eye Center, Ophthalmology and Visual Science Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • Footnotes
    Commercial Relationships  H. Ishikawa, None; G. Wollstein, None; H. Ishikawa, None; M.L. Gabriele, None; A.A. Bonfioli, None; R.J. Noecker, None; D. Greenfield, None; C. Mattox, None; R. Varma, None; J.S. Schuman, Carl Zeiss Meditec, Inc. C, P.
  • Footnotes
    Support  NEI R01–EY13178, R01–EY11289, P30–EY008098. Res to Prevent Blindness. Eye & Ear Found, Pittsburgh.
Investigative Ophthalmology & Visual Science May 2005, Vol.46, 2496. doi:
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      H. Ishikawa, G. Wollstein, H. Ishikawa, M.L. Gabriele, A.A. Bonfioli, R.J. Noecker, D. Greenfield, C. Mattox, R. Varma, J.S. Schuman; Signal Strength Outperformed Signal to Noise Ratio in Evaluating StratusOCT Image Quality . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2496.

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Abstract

Abstract: : Purpose: To compare a newly introduced image quality parameter, signal strength (SS) with the conventional signal to noise ratio (SNR), for optical coherence tomography (OCT; Stratus OCT, Carl Zeiss Meditec, Inc., Dublin, CA) images. Methods: StratusOCT images (linear macular scan and peripapillary circular scan) were analyzed using Stratus 4.0 software. SS and SNR were calculated for each image. Images without any processing (cross–correlation and/or border detection) were exported to an IBM compatible PC, and a software evaluation program was developed so that OCT experts could see StratusOCT images one at a time on a computer monitor while categorizing them by subjective 3–level–grading (excellent, acceptable, and poor). Four OCT experts independently evaluated these images in a randomized fashion, and the outcome results were compared with SS and SNR. Results:270 images of 90 subjects (30 each for normal, early, and advanced glaucoma) were enrolled in this study. Subjects were selected in a consecutive and retrospective fashion from our OCT imaging database. There were significant differences in SS and SNR between each of the categories (excellent vs. poor, acceptable vs. poor, and excellent vs. acceptable) (all p≤0.0003, Wilcoxon test). Areas under the receiver operating characteristic (ROC) curve for discrimination of poor from excellent and acceptable images were 0.89 (SNR) and 0.95 (SS) (p=0.002). The suggested cutoff of SS was 6.28 achieving the best specificity and sensitivity (0.88 and 0.86, respectively). Conclusions: SS was better than SNR in terms of discrimination of poor images. Although the operating manual states that SS of 5 or better can be acceptable, based on the results of this study it is recommended that only images with SS of 6 or greater be used clinically.

Keywords: image processing • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) 
© 2005, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2015 Association for Research in Vision and Ophthalmology.
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