For Siemens:
#Echo Spacing or Dwelltime of fMRI image in seconds =
1/(BandwidthPerPixelPhaseEncode * # of phase encoding samples): DICOM
field (0019,1028) = BandwidthPerPixelPhaseEncode, DICOM field (0051,100b)
AcquisitionMatrixText first value (# of phase encoding samples)
I believe this accounts for GRAPPA factors and partial fourier does not
affect the echo spacing.
Peace,
Matt.
On 3/12/14 1:33 PM, "Estrid Jakobsen" <[log in to unmask]> wrote:
>Dear all,
>
>I am trying to do fieldmap correction of 7T EPI data using FUGUE, which
>requires input of a variable, 'dwell time'. If I've understood correctly,
>this variable actually refers to the 'effective echo spacing' (rather
>than simply the dwell time listed in the DICOM of the EPI data) but there
>seem to be several methods to calculate it.
>
>1. DwellTime = (EchoSpacing/GRAPPA)-1
>
>2. DwellTime = EchoSpacing*((MatrixLines*PartialFourier/GRAPPA)-1)
>
>Which of these options (if either) is correct for running FUGUE?
>
>Many thanks!
>
>Estrid
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