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

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 s...

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Bibliographic Details
Published in:Scientific reports 2016-08, Vol.6 (1), p.32080-32080, Article 32080
Main Authors: Ho, Leon C, Sigal, Ian A, Jan, Ning-Jiun, Yang, Xiaoling, van der Merwe, Yolandi, Yu, Yu, Chau, Ying, Leung, Christopher K, Conner, Ian P, Jin, Tao, Wu, Ed X, Kim, Seong-Gi, Wollstein, Gadi, Schuman, Joel S, Chan, Kevin C
Format: Article
Language:English
Subjects:
Animals
Biomechanics
Cattle
Cornea
Eye
Eye - diagnostic imaging
Eye - metabolism
Glaucoma
Glaucoma - diagnostic imaging
Glaucoma - metabolism
Glyceraldehyde
Intraocular Pressure
Macromolecules
Magnetic resonance imaging
Magnetic Resonance Imaging - methods
Mimicry
Molecular Imaging - methods
Myopia
Myopia - diagnostic imaging
Myopia - metabolism
NMR
Nuclear magnetic resonance
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Summary: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.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep32080