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O. Bergamin, M. Piccirelli, R. Luechinger, M. Soellinger, A. Rutz, P. Boesiger; Two–Dimensional MRI Motion Map of the Vitreous Induced by Eye Movement . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3297.
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© ARVO (1962-2015); The Authors (2016-present)
To understand further mechanisms of vitreo–retinal traction, we investigated the in vivo flow pattern of the vitreous with motion encoded MRI (CSPAMM and CDENSE). So far, the only measurement of the vitreous flow pattern in vivo was done in one dimension. In vitro experiments provided only a description in a spherical model.
For reproducible and accurate eye alignment, subjects fixed upon a horizontal sinusoidally moving target (63°/sec, ±20°). A microscopy coil (47mm diameter) at 1.5T was used to acquire dynamic 2D CSPAMM images (256x151 scan–matrix, 512x512 recon.–matrix, in 6min 21 time frames of 70ms, at a resolution of 0.3x0.3x4 mm3 and tag–line distance: 2mm) and 2D CDENSE images (128x111 scan–matrix, 256x256 recon.–matrix, in 5min 21 time frames of 70ms, 0.6x0.6x5mm3, encoding strength: 3.6mm/pi). Data were post–processed to get displacement maps.
The CSPAMM motion encoded images (Panels A–D) provided information of the movement also within homogeneous regions like the vitreous humor. CDENSE (Panel E) had a higher sensitivity to motion than CSPAMM, but also showed higher noise. Panels A–D: Four CSPAMM images of the clockwise rotating eye (first half of a sinusoidal movement). The vitreous humor moved as a damped oscillator due to its high viscosity. Panel E: CDENSE image of the globe at the change of direction by a sinusoidal movement. The vitreous humor was still turning clockwise as the globe already began to rotate counterclockwise. The vitreous humor movement was clearly affected by the lens of the eye and it was not moving at the center of ocular rotation.
CSPAMM allows the visualization of the vitreous humor motion. CDENSE is more sensitive to noise but allows to detect smaller movements, which may be essential for modeling the vitreous humor movement. This understanding of the in vivo flow pattern of the vitreous humor may give new insights into mechanisms leading to retinal detachment and following reattachment surgery.
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