Application of Diffusion Tensor MRI to Study Neurologic Disease
John Carew
Diffusion tensor imaging is a quantitative magnetic resonance imaging (MRI) method that is widely used to study the microstructural properties of white matter in the brain. Since DTI can provide microstructural information, it can reveal disease-correlated tissue changes that are not evident on conventional MRI. This sensitivity to microstructure and tissue organization makes DTI an important tool for studying neurologic diseases. In addition to studying statistical problems in diffusion imaging, I am interested in applying these imaging techniques to study neurologic diseases such as amyotrophic lateral sclerosis (ALS) and Alzheimer's disease.
The diffusion tensor (a 3x3 covariance matrix) is estimated from a set of diffusion-weighted images that measure diffusion of water molecules in different gradient directions (See figures below).
Diffusion is not equal along all directions, for example diffusion is greater along a neuron than across it.
Since the diffusion tensor D is complicated to visualize at each pixel in an image, univariate measures such as fractional anisotropy (FA) are computed from D. I derived a consistent estimator for the variance of FA.
