Automated Choroidal Segmentation in Enhanced Depth Imaging Optical Coherence Tomography Images

Document Type : Original Article (s)

Authors

1 MSC Student, Department of Biomedical Engineering, School of Medicine AND Student Research Committee, Isfahan University of Medical Sciences, Isfahan, Iran

2 PhD Student, Department of Biomedical Engineering, School of Medicine AND Student Research Committee, Isfahan University of Medical Sciences, Isfahan, Iran

3 Associate Professor, Department of Biomedical Engineering, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

Abstract

Background: Enhanced depth imaging optical coherence tomography images (EDI-OCT) is used for detailed imaging of the choroid layer that contains the highest amount of blood flow in the eye and is affected in several diseases such as choroidal polyps, age-related degeneration and central serous chorioretinopathy. Choroidal segmentation is really important, but the manual segmentation is time consuming and encounters difficulties when large numbers of data is available. Since a large amount of information is available in the images, non-automated and visual analysis of data is almost impossible for the ophthalmologist. The main goal of automatic segmentation was to help the ophthalmologists in the diagnosis and monitoring diseases related to the eye.Methods: The data used in this project was obtained from the Heidelberg OCT-HRA2-KT instrument. Fifty 2 dimensional data were used to evaluate the algorithm. In this study, the retinal pigment epithelium (RPE) and choroid was segmented using a boundary detection algorithm named dynamic programming.Findings: The proposed algorithm was compared with the manual segmentation and the results showed an unsigned error of 1.71 ± 0.93 pixels for retinal pigmented epithelium (RPE) extraction and 10.48 ± 4.11 pixels for choroid detection. It showed significant improvements over other approaches like k-means method.Conclusion: A few automated methods are applied in the choroid segmentation and most of the studies were mainly focused on the manual separation. In this study, a fast and automated method was provided for the segmentation of choroid area.

Keywords


  1. Cioffi GA, Granstam E, Alm A. Ocular circulation. In: Kaufman PL, Alm A, editors. Adler's physiology of the eye. 10th ed. Philadelphia, PA: Mosby; 2003.
  2. Chung SE, Kang SW, Lee JH, Kim YT. Choroidal thickness in polypoidal choroidal vasculopathy and exudative age-related macular degeneration. Ophthalmology 2011; 118(5): 840-5.
  3. Jirarattanasopa P, Ooto S, Tsujikawa A, Yamashiro K, Hangai M, Hirata M, et al. Assessment of macular choroidal thickness by optical coherence tomography and angiographic changes in central serous chorioretinopathy. Ophthalmology 2012; 119(8): 1666-78.
  4. Brown JS, Flitcroft DI, Ying GS, Francis EL, Schmid GF, Quinn GE, et al. In vivo human choroidal thickness measurements: evidence for diurnal fluctuations. Invest Ophthalmol Vis Sci 2009; 50(1): 5-12.
  5. Coleman DJ, Silverman RH, Chabi A, Rondeau MJ, Shung KK, Cannata J, et al. High-resolution ultrasonic imaging of the posterior segment. Ophthalmology 2004; 111(7): 1344-51.
  6. Sarks SH. Ageing and degeneration in the macular region: a clinico-pathological study. Br J Ophthalmol 1976; 60(5): 324-41.
  7. Povazay B, Hermann B, Unterhuber A, Hofer B, Sattmann H, Zeiler F, et al. Three-dimensional optical coherence tomography at 1050 nm versus 800 nm in retinal pathologies: enhanced performance and choroidal penetration in cataract patients. J Biomed Opt 2007; 12(4): 041211.
  8. Spaide RF, Koizumi H, Pozzoni MC. Enhanced depth imaging spectral-domain optical coherence tomography. Am J Ophthalmol 2008; 146(4): 496-500.
  9. Rahman W, Chen FK, Yeoh J, Patel P, Tufail A, Da CL. Repeatability of manual subfoveal choroidal thickness measurements in healthy subjects using the technique of enhanced depth imaging optical coherence tomography. Invest Ophthalmol Vis Sci 2011; 52(5): 2267-71.
  10. Margolis R, Spaide RF. A pilot study of enhanced depth imaging optical coherence tomography of the choroid in normal eyes. Am J Ophthalmol 2009; 147(5): 811-5.
  11. Kajic V, Esmaeelpour M, Povazay B, Marshall D, Rosin PL, Drexler W. Automated choroidal segmentation of 1060 nm OCT in healthy and pathologic eyes using a statistical model. Biomed Opt Express 2012; 3(1): 86-103.
  12. Tian J, Marziliano P, Baskaran M, Tun TA, Aung T. Automatic measurements of choroidal thickness in EDI-OCT images. Conf Proc IEEE Eng Med Biol Soc 2012; 2012: 5360-3.
  13. Bellman RE, Dreyfus SE. Applied dynamic programming. Princeton, NJ: Princeton University Press; 1962.
  14. Sonka M, Hlavac V, Boyle R. Image processing, analysis, and machine vision. Boston, MA: PWS Publishing; 1999.
  15. Shi J, Malik J. Normalized cuts and image segmentation. Journal IEEE Transactions on Pattern Analysis and Machine Intelligence 2013; 22(8): 888-905.
  16. Erdem E. Nonlinear diffusion PDEs [Online]. 2012. Available from: URL: http://web.cs.hacettepe.edu.tr/~erkut/bil717.s12/w04-nonlineardif.pdf.
  17. Kanal LN, Krishnaiah PR. Handbook of statistics 2: classification, pattern recognition and reduction of dimensionality. Amsterdam, Holland: Elsevier Science Pub Co; 1982.
  18. Chiu SL. Fuzzy model identification based on cluster estimation. Journal of intelligent and Fuzzy systems 1994; 2(3): 267-78.