Thanks for taking a look at these. They are similar but still curiously
different. Slice timing correction was not performed. I will check with
our technician regarding any processing that may take place during
conversion.
Are there any other possibilities that may cause this?
Best,
Drew
On 4/16/13 11:49 AM, "Watson, Christopher"
<[log in to unmask]> wrote:
>It's possible that the scanner does some processing steps itself. For
>example, I know the FA images produced directly by the scanner can be
>slightly different than those created by e.g. FSL. The results you posted
>are really quite similar.
>As a guess, perhaps if you're doing slice timing, you have the slice
>acquisition order wrong? Or perhaps the scanner creates motion corrected
>images (I think some Siemens sequences do this).
>________________________________________
>From: Sevel,Landrew S [[log in to unmask]]
>Sent: Tuesday, April 16, 2013 10:54 AM
>To: Watson, Christopher; [log in to unmask]
>Subject: Re: Different Results with Imported DICOM vs NIFTI
>
>Attached are design matrices and glass brain images for each. I noticed
>the motion parameters were slightly different from each approach as well.
>A screen shot of representative values for both is also included. These
>were also included as regressors in the model for each.
>
>Again thanks for all of the assistance.
>
>-Drew
>
>On 4/16/13 1:09 AM, "Watson, Christopher"
><[log in to unmask]> wrote:
>
>>Would you mind attaching screenshots of both situations? It would help
>>immensely in this situation, I should think. This is because, at first
>>glance, using Nifti files from different programs should *not* produce
>>different results. Perhaps the steps you went through were vastly
>>different.
>>________________________________________
>>From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf
>>of Sevel,Landrew S [[log in to unmask]]
>>Sent: Monday, April 15, 2013 1:20 PM
>>To: [log in to unmask]
>>Subject: [SPM] Different Results with Imported DICOM vs NIFTI
>>
>>SPM,
>>
>>I was recently checking some data by comparing a 1st level contrast on an
>>image from a 4D NIFTI file that was created by our scanner to an
>>SPM-converted NIFTI, from the scanner's DICOMs, of the same contrast
>>(processed the same way). This was done in SPM12b. In the DICOM import
>>step, I did receive the message that the algorithm had to guess to
>>construct the NIFTI. Nonetheless, the contrast image produced for each
>>format is different (some activations in one are absent in another, and
>>some activations occur in different places, resembling a coregistration
>>error).
>>
>>What might account for these differences?
>>
>>Best,
>>
>>Drew
>
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