Most tractography methods based on diffusion tensor images (DTIs) require repeated evaluation of tensors or tensor properties at locations not on the point lattice of measurements made during imaging [1]. Furthermore, computing tractwise statistics on scalar measures [2] may also require interpolation to such locations. The process of computing tensor measures comprises two stages: first comput...

Registration of Diffusion-Weighted MR Images (DW-MRI) can be achieved by registering the corresponding 2nd-order Diffusion Tensor Images (DTI). However, it has been shown that higher-order diffusion tensors (e.g. order-4) outperform the traditional DTI in approximating complex fiber structures such as fiber crossings. In this paper we present a novel method for unbiased group-wise non-rigid reg...

Diffusion tensor imaging (DTI) is a powerful tool in the study of the course of nerve fiber bundles in the human brain. Using DTI, the local fiber orientation in each image voxel can be described by a diffusion tensor which is constructed from local measurements of diffusion coefficients along several directions. The measured diffusion coefficients and thereby the diffusion tensors are subject ...

BACKGROUND AND PURPOSE MR diffusion tensor imaging permits detailed visualization of white matter fiber tracts. This technique, unlike T2-weighted imaging, also provides information about fiber direction. We present findings of normal white matter fiber tract anatomy at high resolution obtained by using line scan diffusion tensor imaging. METHODS Diffusion tensor images in axial, coronal, and...

The intensity of an isotropically weighted MR image is proportional to a rotationally invariant measure of bulk diffusion, Trace(D) (where D is the effective diffusion tensor). Such images can be acquired from as few as two diffusion-weighted images (DWIs). Analogously, the intensity of an anisotropically weighted MR image is proportional to a rotationally invariant measure of diffusion anisotr...

Diffusion tensor imaging is often performed by acquiring a series of diffusion-weighted spin-echo echo-planar images with different direction diffusion gradients. A problem of echo-planar images is the geometrical distortions that obtain near junctions between tissues of differing magnetic susceptibility. This results in distorted diffusion-tensor maps. To resolve this we suggest acquiring two ...

Methods– Data acquisition. We scanned 9 healthy subjects (3F/6M, 31.25 ± 4.2y) at three time points separated by a 2 weeks interval. Diffusion-weighted EPI were acquired on a Siemens 3T Verio scanner, b = 1000 s/mm2, on 64 evenly distributed directions plus 2 b = 0 images. Pre-processing. The diffusion-weighted images were regularized and corrected for Rician noise. The diffusion tensor was est...

Quantitative-diffusion-tensor MRI consists of deriving and displaying parameters that resemble histological or physiological stains, i.e., that characterize intrinsic features of tissue microstructure and microdynamics. Specifically, these parameters are objective, and insensitive to the choice of laboratory coordinate system. Here, these two properties are used to derive intravoxel measures of...