Analysis ofb-value calculations in diffusion weighted and diffusion tensor imaging

摘要: Diffusion weighted imaging has opened new diagnostic possibilities by using microscopic diffusion of water molecules as a means image contrast. The directional dependence led to the development tensor imaging, which allows us characterize tissue geometry. link between measured NMR signal and self-diffusion is established so-called b matrices that depend on gradient's direction, strength, timing. However, in calculation b-matrix elements, influence gradients each element matrix often neglected. This may cause errors, turn leads an incorrect extraction coefficients. In cases where are high (high spatial resolution), these errors be substantial. Using generic pulsed gradient spin-echo (PGSE) sequence, effects neglecting demonstrated. By measuring isotropic phantom with this sequence it can analytically well experimentally shown large deviations single elements generated. These obtained applying weighting readout direction dimension combination relatively gradients. systematic avoided full considering all or generating cross-term free signals geometric average two images opposite polarity. importance calculating exact proposed methods based fact more precise parameters for extracting correct property maps, such fractional anisotropy, volume ratio, conductivity maps. © 2005 Wiley Periodicals, Inc. Concepts Magn Reson Part A 25A: 53–66,