In this paper, we propose an adaptive seeding strategy for visualization of diffusion tensor magnetic resonance
imaging (DT-MRI) data using streamtubes. DT-MRI is a medical imaging modality that captures unique water
diffusion properties and fiber orientation information of the imaged tissues. Visualizing DT-MRI data using
streamtubes has the advantage that not only the anisotropic nature of the diffusion is visualized but also the
underlying anatomy of biological structures is revealed. This makes streamtubes significant for the analysis of
fibrous tissues in medical images. In order to avoid rendering multiple similar streamtubes, an adaptive seeding
strategy is employed which takes into account similarity of tensors in a given region. The goal is to automate
the process of generating seed points such that regions with dissimilar tensors are assigned more seed points
compared to regions with similar tensors. The algorithm is based on tensor dissimilarity metrics that take into
account both diffusion magnitudes and directions to optimize the seeding positions and density of streamtubes
in order to reduce the visual clutter. Two recent advances in tensor calculus and tensor dissimilarity metrics
are utilized: the Log-Euclidean and the J-divergence. Results show that adaptive seeding not only helps to cull
unnecessary streamtubes that would obscure visualization but also do so without having to compute the culled
streamtubes, which makes the visualization process faster.
KEYWORDS: Visualization, Brain activation, Brain, Functional magnetic resonance imaging, Volume rendering, Digital video recorders, Opacity, Particles, Convolution, 3D metrology
Modern medical imaging provides a variety of techniques for the acquisition of multi-modality data. A typical
example is the combination of functional and anatomical data from functional Magnetic Resonance Imaging
(fMRI) and anatomical MRI measurements. Usually, the data resulting from each of these two methods is
transformed to 3D scalar-field representations to facilitate visualization. A common method for the visualization
of anatomical/functional multi-modalities combines semi-transparent isosurfaces (SSD, surface shaded display)
with other scalar visualization techniques like direct volume rendering (DVR). However, partial occlusion and
visual clutter that typically result from the overlay of these traditional 3D scalar-field visualization techniques
make it difficult for the user to perceive and recognize visual structures. This paper addresses these perceptual
issues by a new visualization approach for anatomical/functional multi-modalities. The idea is to reduce the
occlusion effects of an isosurface by replacing its surface representation by a sparser line representation. Those
lines are chosen along the principal curvature directions of the isosurface and rendered by a flow visualization
method called line integral convolution (LIC). Applying the LIC algorithm results in fine line structures that
improve the perception of the isosurface's shape in a way that it is possible to render it with small opacity
values. An interactive visualization is achieved by executing the algorithm completely on the graphics processing
unit (GPU) of modern graphics hardware. Furthermore, several illumination techniques and image compositing
strategies are discussed for emphasizing the isosurface structure. We demonstrate our method for the example
of fMRI/MRI measurements, visualizing the spatial relationship between brain activation and brain tissue.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.