Biomedical Engineering Reference
In-Depth Information
brains of such patients, as well as the volume of their outer compartments, are smaller than
the corresponding items in normal control cases. This study aimed at proving whether this
is true or not. For this purpose, white matter, for both normal and dyslexic cases, is first
segmented, and then volumes are calculated and compared. The segmentation is performed
within a novel level set framework. Furthermore, the white matter will be subdivided into
inner and outer compartments to find out exactly which part affects the change in total
volume.
1.
INTRODUCTION
Developmental brain disorders represent one of the most interesting and chal-
lenging research areas in neuroscience. Dyslexia and autism are two of the most
complicated developmental brain disorders that affect the behavior and learning
abilities of children. Dyslexia is characterized by the failure to develop age-
appropriate reading skills despite normal intelligence levels and adequate reading
instruction [1], whereas autism is characterized by qualitative abnormalities in
behavior and higher cognitive functions [2]. One of the major causes of develop-
mental disorders is that some parts of the communications network in the brain
fail to perform their tasks properly, and this may result from a malfunction of the
structure of the minicolumns. Buxhoeveden et al. [3] presented a discussion of
minicolumn structure and their organization in the brain. One of the most effective
tools for the analysis and diagnosis of anatomical changes in brain is Magnetic
Resonance Imaging (MRI). Brambilla et al. [2] introduced a review study that
summarized morphometric brain investigations involving autistic patients in or-
der to examine the brain anatomy and development in autistic brains. Palmen et
al. [4] presented an article discussing the neuropathological findings in autistic
brains and how they correlate with MRI findings. Eliez et al. [5] published an
MRI study that investigated the morphological alteration of temporal lobe gray
matter in dyslexia. One major advantage of using MR imaging in brain studies
is the ability to extract several brain regions such as the cerebral cortex, corpus
callosum, sulci, and white/gray matters, and then calculate some parameters for
these parts (e.g., width, surface area, and volume), and use this information to
discriminate between different diseases or to address a certain disease.
Segmentation of the cerebral cortex and isolating the deep structures (such
as the corpus callosum, brain stem, and ventricles) has always been one of the
most challenging and essential tasks in the pipeline of brain functional analysis.
Over the last decade, deformable models and level sets have shown superiority in
the analysis and quantification of the different brain structures [6-10]. Duncan et
al. [11] presented a volumetric segmentation approach based on level sets in which
two surfaces are evolving simultaneously, each driven by its own image-derived
information while marinating the coupling until a representation of the two bound-
ing surfaces is obtained, and then the layer is segmented. The approach has been
applied in the segmentation of the gray matter of the brain and proved to be very
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