T2 weighted imaging of the bovine eye and 3D reconstruction of the ocular lens’ sutures using tractography

Abstract

TITLE: T2 weighted imaging of the bovine eye.

The adaptation of MRI protocols for the ocular tissue was required to achieve a range of high contrast MRI results from this organ. Among various protocols available, the 3D gradient echo protocol was thought to be the most suitable. During this experiment, it was revealed that the ocular T2 properties vary throughout the eye and especially the ocular lens stood out from the rest of the ocular tissue. Using 3D surface rendering techniques and taking advantage of high contrast and high resolution data from the ocular lens, some iso-surfaces corresponding to different T2 relaxation times were rendered and visualized. It is believed that the concentric volumes detected in the lens were corresponding to its varying water-protein ratio from periphery towards the core of the lens.

TITLE: 3D reconstruction of the ocular lens’ sutures using tractography.

Diffusion Tensor Imaging (DTI) was performed on the bovine ocular lens and it was noticed that the sutures structure of the lens was not distinguishable on images with no diffusion weighting. This was thought to be because of the close water content of the suture structure to its neighbouring fiber cells, leading to a smooth refractive index in the lens. However the sutures structure was evident in the diffusion weighted images, leading to the conclusion that the water mobility in these clefts is higher than that in the neighbouring cells. Using DTI data, eigenvectors were calculated in the 3D space. Streamlines were created in the sutures structure region by tracing the calculated eigenvectors. This 3D rendered structure showed the rotation and penetration of the sutures, from the polar regions towards the core of the lens. From the posterior pole to the anterior pole of the lens, the sutures seemed to rotate close to 60º which is very close to the findings of the literature. This work was encouraging for the future development of DTI technique as a non-invasive imaging method to study structural properties of the ocular lens.