The word tractography refer to any method for estimating the trajectories of the fiber tracts in the white matter.In other words,It is the technique that visually represents the nevers tracts with the Diffusion-Weighted images(DWI).
It is a 3D modeling technique.The images used for analysis is the magnetic resonances imaging(MRI) or Computed Tomography(CT) scan image.Many methods such as streamline tractography under the principle of successuive stepping in the direction of the principle eigen vector,FACT have been proposed for the tractography,and the results will vary enormously depending on the chosen method.In recent,mostly commonly streamline Diffusion Tensor Imaging(DTI) is used to perform tractography.
The most recent trending technology popular for imaging the white matters of the brain is DTI.DTI is a sensitive probe of cellular structure that measures the diffusion of water molecules and the measured diffusion quantity is the diffusion coefficient or diffusivity.Its unit is mm2/s.The macroscopic diffusion measurement in the tissue is anisotropic as measurement varies with direction.
Compare to diffusion MRI,DTI is prior because it provides the crucial invariant description of shape of water diffusion to measure anisotropic diffusion.It is used for fiber tract estimation, volumentric analysis,glyphy derivation,etc.After the estimation of DTI data,it is processed to display fiber tracts.
Fibers trajectories can be selected by ‘virtual dissection’,where inclusion or exclusion of region are defined and used to select trajectories.The more important factor with fiber tracking is that making the voxel isotropic.i.e.in-plane pixel length and section thickness must be same.Hence,the optimizing of DTI for fiber Tracking is more important in fiber tracking.
DTI has many application in neuroradiology such as DTI tractography applied in the measurement of normal maturational changes in development of normal brain and spainal cord,Congenital anomalies and leukodustrophies,also known as Krabee’s disease which is white matter disorder caused by the deficiency of galactocerebrosidase,DTI in MS lesions,DTI fiber tractography,rendering,segmentation of tumor cells,etc.In this paper we dispatch the fiber tractography of human brain using a open-source software.There are many open-source software for Medical Image Analysis Software such as visualization Toolkit(VTK),ITK,FSL,SPM,GIMIAS,3D Slicer,MIA,etc.Here, we used 3D Slicer for fiber tractography.3D Slicer is a platform for 3D visulaization.