Jun-Cheng
Weng1,2, Wen-Yih Iascc Tseng1,3
1Center for Optoelectronic Biomedicine,
National Taiwan University College of Medicine, Taipei, Taiwan; 2Department
of Medical Imaging and Radiological Sciences, Chung Shan Medical University,
Taichung, Taiwan; 3Department of Medical Imaging, National Taiwan
University Hospital, Taipei, Taiwan
The
corpus callosum (CC) is the main fiber tract connecting bilateral cerebral
hemispheres, serving information transfer and processing in various cognitive
functions. In view of the topographically-specific relation between callosal
regions and the connected cortical regions, several partitioning approaches
have been proposed to allow separate analysis of different callosal sectors.
Vertical partitions are commonly used which subdivide the CC into five
regions based on fractions of its maximal anterior-posterior length as
proposed by Wiltelson. These regions might be affected differently in the development
of disease, and their structural parameters such as size and shape might
associate with cognitive or functional tests involved in different modes of
interhemispheric interactions. This study proposed a novel technique,
q-planar imaging (QPI) to map the relative axonal diameters of CC in normal
human brain. It was based on the Fourier relationship between probability
density function (PDF) of the water molecular diffusion and sampled diffusion
attenuated images in the space of spatial modulation, dubbed q-space. It
provided MR images in which physical parameters of water diffusion such as
the mean displacement and the probability at zero displacement of water
molecules were used as image contrast. Our results demonstrated that QPI
produced reasonable distribution of relative axonal diameters of CC in normal
human brain.