title: A theoretical validation of the B-matrix spatial distribution approach to diffusion tensor imaging.
abstract: The recently presented B-matrix Spatial Distribution (BSD) approach is a calibration technique which derives the actual distribution of the B-matrix in space. It is claimed that taking into account the spatial variability of the B-matrix improves the accuracy of diffusion tensor imaging (DTI). The purpose of this study is to verify this approach theoretically through computer simulations. Assuming three different spatial distributions of the B-matrix, diffusion weighted signals were calculated for the six orientations of a model anisotropic phantom. Subsequently two variants of the BSD calibration were performed for each of the three cases; one with the assumption of high uniformity of the model phantom (uBSD-DTI) and the other taking into account imperfections in phantom structure (BSD-DTI). Several cases of varying degrees of phantom uniformity were analyzed and the distributions of the B-matrix obtained were used for the calculation of the diffusion tensor of a model isotropic phantom. The results were compared with standard diffusion tensor calculation. The simulations confirmed the improvement of accuracy in the determination of the diffusion tensor after the calibration. BSD-DTI improves accuracy independent of both the degree of uniformity of the phantom and the inhomogeneity of the B-matrix. In cases of a relatively good uniformity of the phantom and minor distortions in the spatial distribution of the B-matrix, the uBSD-DTI approach is sufficient.
authors.affiliation: Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059, Cracow. Electronic address: Karol.Borkowski@fis.agh.edu.pl.
authors.forename: Karol
authors.initials: K
authors.lastname: Borkowski
authors.affiliation: Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059, Cracow.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kłodowski
authors.affiliation: Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059, Cracow.
authors.forename: Henryk
authors.initials: H
authors.lastname: Figiel
authors.affiliation: Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, al. Mickiewicza 30, 30-059, Cracow.
authors.forename: Artur Tadeusz
authors.initials: AT
authors.lastname: Krzyżak
mesh_terms: D002138:Calibration; D003198:Computer Simulation; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
keywords: Anisotropy; DTI; Diffusion; MRI; Phantoms