title: A new semi-quantitative approach for analysing 3T diffusion tensor imaging of optic fibres and its clinical evaluation in glaucoma.
abstract: OBJECTIVE
  Diffusion tensor imaging can depict rarefaction of the optical fibers. Manual segmentation is time consuming. The purposes of the study were (1) to present a new semiquantitative segmentation approach for analyzing 3-T diffusion tensor imaging of optical fibers and (2) to clinically test the new approach by comparing optic fiber rarefaction in patients with glaucoma to that in age-matched, healthy controls.
  
  
  METHODS
  To perform semiautomated and quantitative segmentation of the optical radiation, a Mathcad-based software program was developed. The results were compared to the manual evaluation of the images performed by two experienced neuroradiologists. The eyes of 42 subjects (22 patients with glaucoma and 20 controls) aged 37 to 86 years were assessed in full ophthalmologic examinations. Magnetic resonance imaging was performed using a 3-T high-field scanner.
  
  
  RESULTS
  The evaluation using the new approach matched 94% with manually acquired rarefaction of the optical radiation; Cronbach's α was >0.81 for calculation of the manually and semiautomatically derived volumes.
  
  
  CONCLUSIONS
  The new approach seems to be robust and is clearly faster compared to the more tedious manual segmentation. Using diffusion tensor imaging at 3 T, it could be shown that there was increasing atrophy of the optical radiation (fourth neuron) with increasing age in patients with glaucoma. Compared to age-matched, healthy patients, more pronounced atrophy of the fourth neuron was found in patients with glaucoma.
authors.affiliation: Department of Neuroradiology, University Erlangen-Nuremberg, D-91054 Erlangen, Germany. tobias.engelhorn@uk-erlangen.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Engelhorn
authors.forename: Sultan
authors.initials: S
authors.lastname: Haider
authors.forename: Georg
authors.initials: G
authors.lastname: Michelson
authors.forename: Arnd
authors.initials: A
authors.lastname: Doerfler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005901:Glaucoma / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000473:pathology*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity