7.1 T MRI to assess the anterior segment of the eye.
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.
Langner
Sönke
S
Institute for Diagnostic Radiology and Neuroradiology, University of Greifswald, Greifswald, Germany.
Martin
Heiner
H
Terwee
Thom
T
Koopmans
Steven A
SA
Krüger
Paul C
PC
Hosten
Norbert
N
Schmitz
Klaus-Peter
KP
Guthoff
Rudolf F
RF
Stachs
Oliver
O
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