title: A novel automated segmentation method for retinal layers in OCT images proves retinal degeneration after optic neuritis.
abstract: OBJECTIVE
  The evaluation of inner retinal layer thickness can serve as a direct biomarker for monitoring the course of inflammatory diseases of the central nervous system such as multiple sclerosis (MS). Using optical coherence tomography (OCT), thinning of the retinal nerve fibre layer and changes in deeper retinal layers have been observed in patients with MS. Here, we first compare a novel method for automated segmentation of OCT images with manual segmentation using two cohorts of patients with MS. Using this method, we also aimed to reproduce previous findings showing retinal degeneration following optic neuritis (ON) in MS.
  
  
  METHODS
  Based on a 5×5 expansion of the Prewitt operator to efficiently calculate the gradient of image intensity, we introduce an automated algorithm for the segmentation of intraretinal layers. We evaluated this algorithm by comparison to manually segmented two-dimensional OCT images at the macular level for 125 patients from two separate cohorts of patients with MS. Of these patients, 52 had suffered from unilateral ON+ within 6 months prior to measurement.
  
  
  RESULTS
  When comparing ON+ eyes with ON- eyes, both manual and automated segmentation demonstrated a significant inter-eye thinning in the ganglion cell layer in ON+ eyes. We also observed an increased thickness of the inner nuclear (INL) and the outer segment-retinal pigment epithelium (OS-RPE) layers of ON+ eyes in both cohorts. These findings corroborate previous data, thus demonstrating the validity of our approach.
  
  
  CONCLUSIONS
  The algorithm presented here was found to be a valid tool for replacing cumbersome manual segmentation methods in the quantification of inner retinal layers in OCT. The observed increases in thickness of INL and OS-RPE may be attributed to primary retinal inflammation, repair and/or plasticity mechanisms following the immune attack.
authors: Department of Neurology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University, Mainz, Germany.
authors: Amgad
authors: A
authors: Droby
authors: Department of Neurology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
authors: Michail
authors: M
authors: Panagoulias
authors: Medical Faculty, Department of Neurology, Heinrich Heine University, Düsseldorf, Germany.
authors: Philipp
authors: P
authors: Albrecht
authors: Department of Neurology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
authors: Eva
authors: E
authors: Reuter
authors: Department of Neurology, University Hospital, Münster, Germany.
authors: Thomas
authors: T
authors: Duning
authors: Department of Computer Science, Johannes Gutenberg University, Mainz, Germany.
authors: Andreas
authors: A
authors: Hildebrandt
authors: Department of Neurology, University Hospital, Münster, Germany.
authors: Heinz
authors: H
authors: Wiendl
authors: Department of Neurology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University, Mainz, Germany.
authors: Frauke
authors: http://orcid.org/0000-0002-1231-1928
authors: F
authors: Zipp
authors: Department of Neurology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
authors: Axel
authors: A
authors: Methner
mesh_terms: D000328:Adult; D000465:Algorithms; D015415:Biomarkers; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000175:diagnosis*; D009412:Nerve Fibers / Q000473:pathology*; D009902:Optic Neuritis / Q000150:complications / Q000175:diagnosis*; D015203:Reproducibility of Results; D012162:Retinal Degeneration / Q000175:diagnosis* / Q000209:etiology; D055351:Retinal Neurons / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: Imaging; Immunology; Optic Nerve; Pathology; Retina