title: Automated image alignment and segmentation to follow progression of geographic atrophy in age-related macular degeneration.
abstract: OBJECTIVE
  To develop a computer-based image segmentation method for standardizing the quantification of geographic atrophy (GA).
  
  
  METHODS
  The authors present an automated image segmentation method based on the fuzzy c-means clustering algorithm for the detection of GA lesions. The method is evaluated by comparing computerized segmentation against outlines of GA drawn by an expert grader for a longitudinal series of fundus autofluorescence images with paired 30° color fundus photographs for 10 patients.
  
  
  RESULTS
  The automated segmentation method showed excellent agreement with an expert grader for fundus autofluorescence images, achieving a performance level of 94 ± 5% sensitivity and 98 ± 2% specificity on a per-pixel basis for the detection of GA area, but performed less well on color fundus photographs with a sensitivity of 47 ± 26% and specificity of 98 ± 2%. The segmentation algorithm identified 75 ± 16% of the GA border correctly in fundus autofluorescence images compared with just 42 ± 25% for color fundus photographs.
  
  
  CONCLUSIONS
  The results of this study demonstrate a promising computerized segmentation method that may enhance the reproducibility of GA measurement and provide an objective strategy to assist an expert in the grading of images.
authors.affiliation: *Wilmer Eye Institute, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, Maryland; †Hoover Rehabilitation Low Vision Services, Greater Baltimore Medical Center, Baltimore, Maryland; and ‡Department of Computer Science, Johns Hopkins University, Baltimore, Maryland.
authors.forename: David J
authors.initials: DJ
authors.lastname: Ramsey
authors.forename: Janet S
authors.initials: JS
authors.lastname: Sunness
authors.forename: Poorva
authors.initials: P
authors.lastname: Malviya
authors.forename: Carol
authors.initials: C
authors.lastname: Applegate
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Hager
authors.forename: James T
authors.initials: JT
authors.lastname: Handa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003941:Diagnostic Techniques, Ophthalmological; D018450:Disease Progression; D005189:False Positive Reactions; D005260:Female; D005584:Fovea Centralis / Q000473:pathology; D057092:Geographic Atrophy / Q000175:diagnosis*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity