In this case, yes, but thanks for the caution. I'll switch it on my end
to search for "AcquisitionMatrixText" instead.
On 03/12/2014 02:27 PM, Harms, Michael wrote:
> Are you sure that the value of the "PhaseEncodingLines" string is the same
> as the first value of "AcquisitionMatrixText", in instances of GRAPPA,
> partial Fourier, etc?
>
> cheers,
> -MH
>
> --
> Michael Harms, Ph.D.
>
> -----------------------------------------------------------
> Conte Center for the Neuroscience of Mental Disorders
> Washington University School of Medicine
> Department of Psychiatry, Box 8134
> 660 South Euclid Ave. Tel: 314-747-6173
> St. Louis, MO 63110 Email: [log in to unmask]
>
>
>
>
> On 3/12/14 2:05 PM, "Joel Bruss" <[log in to unmask]> wrote:
>
>> 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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