open-discussion > missing gradients
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Dec 12, 2018  08:12 AM | karen
missing gradients
Dear all, 

When looking in the QCReport.txt files I noticed that there are gradients missing in the list of "Included gradients", which are not listed as interlace-wise check artifacts or slice-wise check artifacts (I'm skipping gradient-wise check). In fact, they are not mentioned in the report at all. This usually happens for 1-2 gradients in about 1 per 8 subjects. Does somebody know what happened to those gradients?

For example, in the file attached, you can see that gradient 42 is not listed as an included gradient and neither as an interlace-wise or slice wise artifact. 

Thanks, 
Karen
Attachment: DTIPrep_QCReport
Dec 14, 2018  08:12 AM | Martin Styner
RE: missing gradients
Originally posted by karen:
Dear all, 

When looking in the QCReport.txt files I noticed that there are gradients missing in the list of "Included gradients", which are not listed as interlace-wise check artifacts or slice-wise check artifacts (I'm skipping gradient-wise check). In fact, they are not mentioned in the report at all. This usually happens for 1-2 gradients in about 1 per 8 subjects. Does somebody know what happened to those gradients?

For example, in the file attached, you can see that gradient 42 is not listed as an included gradient and neither as an interlace-wise or slice wise artifact. 

Thanks, 
Karen
Hi Karen
I could not see the attached file (not sure what's wrong with it, but I cannot download it from NITRC). Is gradient 42 a baseline/b=0 volume? If so then it would be missing, as it was averaged with the other b=0 volumes.
Martin
Dec 17, 2018  07:12 AM | karen
RE: missing gradients
Hi Martin,

Thanks for your response. In this case gradient 42 was a baseline volume (and I would have expected it to be listed with the other baseline volumes "Baselines_indices" in the list ). However, it also seems to happen for gradients, i.e. not baseline volumes. I attached another file, in which gradient 87 is not in the list of included gradients and not listed among the artifacts (and it is not a baseline volume).

Best, 
Karen