BMMR2: Breast Multiparametric MRI for prediction of NAC Response Forum

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> DWI DICOM header tags question for data from GE sites

Hello! In loading and processing the training data, we find that the DWI b=100 images have headers which indicate which of the 4 images is the trace and which 3 are the directional saved images before geometric averaging. For the GE data, it's not (readily) apparent which tag indicates the trace image. Is there a tag that labels these? We can guess, but it seems useful to know if there is a GE tag we're missing. :) Thanks!

Posted by: jcdicarlo @ July 26, 2021, 7:32 p.m.

Hi Julie:
Sorting out the image order in the old GE scans can be a real challenge! They were terribly inconsistent in how they stored things.
For the 6698 studies it is only an issue for sites that had the "recon all" option set, which told the scanner to keep the directional DWI images.
I'm afraid there is no definitive way from the DICOM headers to identify which image is which in these cases. Looks like the only field that might have made that possible did not make it through the deidentification process :( .
I _think_ you can always (for this data set) sort the images by the InstanceNumber (0020,0013) and assume the following order for the volumes in the series:
<b=100 Tr>
<b=600 Tr>
<b=800 Tr>
<b=0> (average of all b=0, but that is only a single one in the 6698 protocol)
<b=100 Dir.1>
<b=600 Dir.1>
...
<b=800 Dir. 3>

For the site that did 3 scans of 2 b-values each the pattern is the same, just there is only a single b-value for each direction.
Hope that is helpful.
David

Posted by: Newitt @ Aug. 2, 2021, 4:37 p.m.

PS.
What I called the "trace" images in that previous response to not check out exactly as trace images by what I think is the standard definition (geometric mean of the 3 directional images). They are close, but there are differences. I've put the question as to how these are calculated to a contact at GE. If I get more information I will post it here.
The derived objects labeled "TRACE" are the geometric mean of the directional images for these acquisitions.

David

Posted by: Newitt @ Aug. 2, 2021, 5:28 p.m.

Thank you so much, David!!

Posted by: jcdicarlo @ Aug. 5, 2021, 3:49 p.m.
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