*CJ Holmes PhD, S Haney MD, PM Thompson PhD, JR Alger PhD, TF Cloughesy MD, *A Elekes PhD, AW Toga PhD
Laboratory of Neuro Imaging, Dept. Neurology, Division of Brain Mapping,
UCLA School of Medicine, Los Angeles CA 90095, USA,
*SGI Inc., Mountain View, CA
Tensor maps reveal the profiles of growth in brain tissue. In this case of tumor growth, both the magnitude and principal directions of growth can be visualized; the shape and orientation of the glyphs help illustrate the dynamics of growth in the tissue.
Imaging. 3D gadolinium-enhanced T1-weighted (256x256 resolution; 3 mm spacing) SPGR MRI volumes were acquired over a three month period from a patient with a glioblastoma multiforme (GBM). Scans were automatically aligned into Talairach stereotaxic space with 6-parameter rigid transformations. A volume containing the lesion was identified and extracted from each serial image. These volumes were intensity normalized and converted into three dimensional (64x64x64) luminosity-only TIFF files.
Dynamic Visualization. For dynamic visualization, the data were rendered interactively using the OpenGL Volumizer library on an SGI Onyx2 InfiniteReality2 graphics pipeline. Each volume could be interactively rotated, zoomed and intensity and transparency adjusted for visualization of embedded objects. Most significantly, sixteen serial volumes could be interactively visualized in sequence, providing the ability to visualize the change in tumor dimension over time in a three dimensional fashion.
As the required hardware was too large to be conveyed to an operating room environment, the Vizserver software was employed to harness the graphics capability of the InfiniteReality2 hardware on a remote desktop workstation, across commodity 100bT network interfaces. The combination of long term dynamic volumetric visualization with remote viewing capability provided significant benefits for tracking the patient's progress in a distributed medical environment.
Paul Thompson, Ph.D.
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