Format

Send to

Choose Destination
Sci Rep. 2016 Aug 26;6:32080. doi: 10.1038/srep32080.

Non-invasive MRI Assessments of Tissue Microstructures and Macromolecules in the Eye upon Biomechanical or Biochemical Modulation.

Ho LC1,2,3, Sigal IA2,3,4,5, Jan NJ2,6, Yang X1,2, van der Merwe Y1,2,6,4,5, Yu Y7, Chau Y7,8, Leung CK9,10, Conner IP2,4,5, Jin T1, Wu EX3, Kim SG1,6,4,11,12,13, Wollstein G2,6,4,5, Schuman JS2,6,4,11,14, Chan KC1,2,6,4,5,11.

Author information

1
NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA.
2
UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
3
Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China.
4
McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
5
Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA.
6
Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
7
Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Hong Kong, China.
8
Division of Biomedical Engineering, Hong Kong University of Science and Technology, Hong Kong, China.
9
University Eye Center, Hong Kong Eye Hospital, Hong Kong, China.
10
Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
11
Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA.
12
Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Korea.
13
Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea.
14
Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, PA, USA.

Abstract

The microstructural organization and composition of the corneoscleral shell (CSS) determine the biomechanical behavior of the eye, and are important in diseases such as glaucoma and myopia. However, limited techniques can assess these properties globally, non-invasively and quantitatively. In this study, we hypothesized that multi-modal magnetic resonance imaging (MRI) can reveal the effects of biomechanical or biochemical modulation on CSS. Upon intraocular pressure (IOP) elevation, CSS appeared hyperintense in both freshly prepared ovine eyes and living rat eyes using T2-weighted MRI. Quantitatively, transverse relaxation time (T2) of CSS increased non-linearly with IOP at 0-40 mmHg and remained longer than unloaded tissues after being unpressurized. IOP loading also increased fractional anisotropy of CSS in diffusion tensor MRI without apparent change in magnetization transfer MRI, suggestive of straightening of microstructural fibers without modification of macromolecular contents. Lastly, treatments with increasing glyceraldehyde (mimicking crosslinking conditions) and chondroitinase-ABC concentrations (mimicking glycosaminoglycan depletion) decreased diffusivities and increased magnetization transfer in cornea, whereas glyceraldehyde also increased magnetization transfer in sclera. In summary, we demonstrated the changing profiles of MRI contrast mechanisms resulting from biomechanical or biochemical modulation of the eye non-invasively. Multi-modal MRI may help evaluate the pathophysiological mechanisms in CSS and the efficacy of corneoscleral treatments.

PMID:
27561353
PMCID:
PMC5000015
DOI:
10.1038/srep32080
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Nature Publishing Group Icon for PubMed Central
Loading ...
Support Center