Detailed Obital 3D-Vsualization

Abstract

 

Purpose:

 

To present a highly detailed 3D-visualization of the orbit with focus on the extra ocular muscles (EOM), orbital nerves and vessels, orbital fat and lacrimal gland (LG) in a post mortem control, a control and patients with TAO.

 

Methods:

 

First, MRI data sets are registered to CT. After processing the CT data using a special contour filter, the orbital cavity can be segmented. Thereby, the MRI voxels representing the orbit can be selected and visualized by direct volume rendering using a special transfer function. Shaded rendering of the globe and superpositioning of the original MRI facilitates anatomic orientation. With standard MRI resolution, orbital blood vessels and nerves can be visualized in 3D. Variable clipping planes enable free view to the inner orbital structures. Validation is provided by comparison of the visualizations of the same case based on different MRI protocols.

 

Results:

 

For the EOM, the separation between bulbar and global layer can be observed. Orbital nerves and vascular structures can be analyzed using special positions of the clipping plane. Nerves, such as the nasociliary nerve (fig.1), are rendered with high contrast whereas vascular structures are displayed as dark lines. Both parts of the LG can be visualized in detail. In TAO the marked enlargement of the LG, the EOM and the orbital fat can be seen in 3D.

 

Conclusions:

 

The diagnostic potential of the detailed 3D rendering of the orbit needs further evaluation esp. in regard to visualization of orbital nerves. The effect of TAO on the EOM and the LG can be further studied. An additional benefit of the approach is expected for the detection of LG tumor. In the long run, the 3D-visualization should be rendered dynamically for functional diagnosis support.  

 

Keywords: orbit • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • lacrimal gland