Corpus Callosum parcellation in 5 regions

The CC is one of the few white matter tracts that can be discretely identified by conventional MRI and its morphology may be related to dyslexia, Tourette's syndrome, Down's syndrome, depression, schizophrenia, and HIV/AIDS. Due to the fact that there are no macroscopic anatomical landmarks that clearly delimit distinct callosal areas in a midsagittal cross-section, geometric partitioning schemes have been designed to subdivide the CC, such as the Witelson's classification, although the underlying data predominantly originates from non-human primates (Witelson, 1989). This scheme defines five vertical callosal segments based on specific arithmetic fractions of the maximum anterior–posterior extent (figure 1).

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Figura 1: Witelson's scheme

The goal of this project is to propose a segmentation method based on the hierarchical watershed transform and on the tensorial morphological gradient (TMG).

Main challenges:

  • Interpolation of the raw data will be probably necessary;
  • The TMG computation should be adapted to the CC parcellation problem, by choosing a proper dissimilarity function;
  • Markers selection for the watershed transform play a huge role in this application, since the resolution of DTI is low;
  • Due to the anatomical inter-subject variability, it is difficult to draw meaningful conclusions based on comparisons with histological atlases and theoritical schemes. There is no subject-specific gold standard. Qualitative and quantitative analyses should be performed in a group of subjects.

Msc Dissertation presented by Pedro Ferro

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