Generalized MAGSTE with bipolar diffusion-weighting gradient pulses

Finsterbusch, Jürgen

doi:10.1016/j.jmr.2009.05.004

Cited by 2 publications

(2 citation statements)

References 24 publications

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“…In an intermediate motional regime, a general prediction cannot easily be made (21), but it seems reasonable to assume that interactions between background and DW gradients cannot be completely suppressed anymore. There are even sequences for suppression of varying background gradient contributions (22)(23)(24)(25)(26)(27) but, again, they can only fully compensate for cross terms of background gradients that are constant during application of the DW gradients (25,26). Furthermore, they are based on an extension of the stimulated-echo sequence where additional refocusing pulses are inserted in the DW period, which reduces the signal-to-noise ratio to some extent.…”

Section: Introductionmentioning

confidence: 99%

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BOLD background gradient contributions in diffusion‐weighted fMRI—comparison of spin‐echo and twice‐refocused spin‐echo sequences

2010

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The interaction ('cross terms') between diffusion-weighting gradients and susceptibility-induced background gradient fields around vessels has an impact on apparent diffusion coefficient (ADC) measurements and diffusion-weighted functional magnetic resonance imaging (DFMRI) experiments. Monte-Carlo (MC) simulations numerically integrating the Bloch equations for a large number of random walks in a vascular model were used to investigate to what extent such interactions would influence the extravascular signal change as well as the ADC change observed in DFMRI experiments. The vascular model consists of a set of independent, randomly oriented, infinite cylinders whose internal magnetic susceptibility varies as the state changes between rest and activation. In such a network, the cross terms result in the observation of a functional increase in ADC accompanied by a descending percent signal change with increasing diffusion weighting. It is shown that the twice-refocused spin-echo sequence permits sufficient yet not total suppression of such effects compared to the standard Stejskal-Tanner spin-echo diffusion weighting under experimentally relevant conditions.

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Section: Introductionmentioning

confidence: 99%

“…Furthermore, they are based on an extension of the stimulated-echo sequence where additional refocusing pulses are inserted in the DW period, which reduces the signal-to-noise ratio to some extent. Some of methods developed for cross-term compensation have already been used in vivo (25)(26)(27).…”

Section: Introductionmentioning

confidence: 99%