Thanks for that, Matt. I'd read something similar before but the DICOM
I have has "Unimplemented" in the 0019,1028 header field. 0051,100b
doesn't exist as well. I had to use the ascii header to grab the same
information:
dcmPic=`ls *dcm | sort -t. -k 5 -n | head -1 | tail -1`
BWpe=`strings $dcmPic | grep -A1 "BandwidthPerPixelPhaseEncode" | head
-2 | tail -1`
dimpe=`strings $dcmPic | grep -A1 "PhaseEncodingLines" | head -1 | awk
'{print $3}'`
dwellTime=`echo $BWpe $dimpe | awk '{print (1/($1*$2))}'`
Hope this helps someone else.
-Joel
On 03/12/2014 01:58 PM, Matt Glasser wrote:
> 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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