The presence of Rician noise in magnetic resonance imaging (MRI) introduces systematic errors in diffusion tensor imaging (DTI) measurements. This paper evaluates gradient direction schemes and tensor estimation routines to determine how to achieve the maximum accuracy and precision of tensor derived measures for a fixed amount of scan time. We present Monte Carlo simulations that quantify the ...

In this paper, we present an affine image coregistration technique for Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) data sets based on mutual information. The technique is based on a multichannel approach where the diffusion weighted images are aligned according to the corresponding acquisition gradient directions. Also, in addition to the coregistration of the DT-MRI data sets, an appr...

This study describes a method of utilizing unaveraged dipolar effects to characterize and compute collagen fiber tracks using magnetic resonance imaging. The technique yields information about fiber structure with some similarities to what can be obtained in brain using diffusion tensor imaging, but relies on a completely different physical mechanism, namely, unaveraged homonuclear dipolar inte...

Recently, a novel Direct String Magnetic Gradiometer (DSMG) has been developed, where a vibrating wire, driven by an AC current, is used as a single sensitive element. It is designed to directly measure the local off-diagonal components of the magnetic gradient tensor, Bxz, Byz and Bxy, provided the distance to an object creating magnetic anomalies is much larger than the length of the string. ...

Magnetic resonance (MR) diffusion tensor imaging (DTI) can resolve the white matter fiber orientation within a voxel provided that the fibers are strongly aligned. However, a given voxel may contain a distribution of fiber orientations due to, for example, intravoxel fiber crossing. The present study sought to test whether a geodesic, high b-value diffusion gradient sampling scheme could resolv...

results stereoscopic displays of the nerves were obtained in all 24 elbows by vr, mip, and fiber tractography post-processing methods. the vr/mip post-processing methods were easier to perform compared to fiber tractography. there was no significant difference among the scores of fiber tracking and vr/mip reconstruction for single direction. the imaging quality scores of fiber tractography and ...

We describe a fully-vectorial, three-dimensional algorithm to compute the definite-frequency eigenstates of Maxwell's equations in arbitrary periodic dielectric structures, including systems with anisotropy (birefringence) or magnetic materials, using preconditioned block-iterative eigensolvers in a planewave basis. Favorable scaling with the system size and the number of computed bands is exhi...

The one-loop vacuum polarization tensor is computed in QED with an external constant, homogeneous magnetic field at finite temperature. The Schwinger proper-time formalisme is used and the computations are done in Euclidian space. The well-known results are recovered when the temperature and/or the magnetic field are switched off and the effect of the magnetic field on the Debye screening is di...