My PhD research, so far, is primarily focused on Diffusion Tensor Imaging (DTI) and its statistical analysis. To be specific, I have worked on DTI Atlas building and tract based statistical analysis to perform group statistics.


DTI Atlas building

DTI Atlas building tries to map all the DTI images into a common coordinate framework in order to facilitate statistical analysis of diffusion parameters across the population. The pipeline first estimates the individual tensors and their respective scalar measures using Dtiprocess tools. Next, an unbiased, deformable atlas building procedure is applied by using AtlasWerks to bring the population of datasets into the common coordinate frame. To maintain the relationship between the deformed diffusion images and the respective tensor orientation, we use Riemannian framework to average tensors. For more details about the pipeline, click here


Tract-based Statistical analysis

After reconstructing fiber-tracts using streamline integration method, the diffusion measures corresponding to these tracts provide a means to perform population studies in neuroimaging. DTI atlas building produces a global spatial normalization in order to parameterize these diffusion properties across the population. Thus, it provides a clinically interpretable structure to analyze group differences. To carry out these group differences along the tracts, the techniques including Principal Component Analysis (PCA) and nonparametric permutation tests have been used.

Volumetric segmentation

Volumetric Approach to segment WM tract in DTI

A volumetric segmentation framework is used to study the white matter connectivity, specifically the corticospinal tract (CST). The methodology is based on Fletcher et al and uses Hamilton-Jacobi (H-J) formulation and a fast iterative method to minimize the cost between two target regions. The resulting high-connectivity voxels represent the volumetric pathway of the required tract between two regions.
[MICCAI2011-DTI Tractography Challenge]


Veni G, Hao X, Zygmunt K, Fletcher T, Whitaker, R; DTI Tractography Challenge- MICCAI 2011: A Volumetric Approach to extract Corticospinal tract in Diffusion Tensor MRI. DTI Tractography for Neurosurgical Planning: A Grand Challenge-MICCAI (2011)