title: 7.1 T MRI to assess the anterior segment of the eye.
abstract: OBJECTIVE
  Visualization of the anterior segment and biometric evaluation of the entire crystalline lens pose significant challenges for imaging techniques because of tissue-induced distortion artifacts. The present study was conducted to demonstrate the advantages of high-resolution magnetic resonance imaging (micro-MRI) for visualizing the anterior segment.
  
  
  METHODS
  High-resolution MR ocular images were acquired on an ultra-high-field MR unit using a two-channel coil with four coil elements and T(2)-weighted turbo spin echo sequences ex vivo in pig, rabbit, monkey, and human donor eyes and in vivo in rabbits. Tissue heating, reproducibility, and signal-to-noise ratio were investigated in vivo. Monkey eye lens thickness (LT) was also measured using A-scan ultrasonography (US).
  
  
  RESULTS
  Anterior segment details of phakic eyes were obtained ex vivo (pig, rabbit, monkey, and human donor eyes) with pixel matrix size 512 × 512 (in-plane resolution 80 × 80 μm) and in vivo (rabbit eyes) with pixel matrix size 320 × 320 (in-plane resolution 125 × 125 μm). Complete quantification of lens dimensions as they correlate with the sulcus-sulcus and angle-angle plane can be performed. In LT determinations in monkey eyes, no significant difference was detected between micro-MRI and A-scan US (P > 0.05, Mann-Whitney U test). Biometric analysis of one pseudophakic monkey eye confirmed the absence of relevant distortion artifacts.
  
  
  CONCLUSIONS
  Micro-MRI allows ex vivo and in vivo visualization and quantification of the spatial arrangement of the anterior eye segment. Imaging of the retroiridian region, including the entire crystalline lens, overcomes a number of major limitations in the quantitative evaluation of the anterior segment.
authors.affiliation: Institute for Diagnostic Radiology and Neuroradiology, University of Greifswald, Greifswald, Germany.
authors.forename: Sönke
authors.initials: S
authors.lastname: Langner
authors.forename: Heiner
authors.initials: H
authors.lastname: Martin
authors.forename: Thom
authors.initials: T
authors.lastname: Terwee
authors.forename: Steven A
authors.initials: SA
authors.lastname: Koopmans
authors.forename: Paul C
authors.initials: PC
authors.lastname: Krüger
authors.forename: Norbert
authors.initials: N
authors.lastname: Hosten
authors.forename: Klaus-Peter
authors.initials: KP
authors.lastname: Schmitz
authors.forename: Rudolf F
authors.initials: RF
authors.lastname: Guthoff
authors.forename: Oliver
authors.initials: O
authors.lastname: Stachs
mesh_terms: D000328:Adult; D000818:Animals; D000869:Anterior Eye Segment / Q000033:anatomy & histology*; D001699:Biometry; D001831:Body Temperature; D006801:Humans; D007908:Lens, Crystalline / Q000000981:diagnostic imaging; D008251:Macaca; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D011817:Rabbits; D013552:Swine; D014463:Ultrasonography