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E. Vaghefi Rezaei, M. Jacobs; Visualization of Diffusion Inside the Ocular Lens Using MRI. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4392.
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The sense of vision requires that light penetrate through the ocular lens and that is dependent on the ocular lens transparency. A variety of experiments has suggested that the lens relies on internal directed ion and water fluxes for its circulation, survival and transparency (Donaldson et al 2001).Imaging techniques based on High Field Magnetic Resonance Imaging (HF-MRI) now span many modalities, which have been developed in order to study different properties of tissue. The most commonly used MRI modalities are T1-, T2- and proton density-weighted imaging (Stark et al 1988). These techniques are used to distinguish different tissues based on their intrinsic physiological properties. More complex and sophisticated MRI modalities include contrast agent-enhanced imaging, and diffusion tensor imaging (DTI). We have recently adopted these modalities for use in the ocular lens. We investigated the internal diffusive pathways of the lens in order to understand better the constraints that may be operating on directional lens fluxes.
Magnetic resonance imaging, including T2-weighted imaging and DTI, has been used to acquire data on tissue properties and diffusivity inside intact, cultured bovine lenses.
Several concentric regions of signal intensity were distinguished inside the lens, by both T2-weighted and mean diffusivity (MD) signal (Le Bihan et al 2001). The magnetic resonance data were consistent with some of the known developmental and biochemically distinct lenticular zones that have been defined previously in the literature. Diffusivity mapping of the intact lens revealed reproducible, anisotropic zones of pronounced diffusivity in certain lens regions. Other areas of the lens showed isotropic and weak diffusivity.
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