questions > Slice Direction
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Apr 8, 2015 04:04 AM | Marco LO
Slice Direction
I got a "WARNING: Unable to determine slice direction: please check
whether slices are flipped" in converting Symbia Tomo Recon SPECT
image. What is expected correct orientations when the image
is display in MRICron?
My understanding is DICOM slice and slice-wise direction can be determined from the
three values of the Image Position (Patient) (0020,0032) attribute. If the sign of the first two values are reversed in NIfTI qoffset then could I confirmed that the conversion is correct?
Thanks & Regards,
Marco
My understanding is DICOM slice and slice-wise direction can be determined from the
three values of the Image Position (Patient) (0020,0032) attribute. If the sign of the first two values are reversed in NIfTI qoffset then could I confirmed that the conversion is correct?
Thanks & Regards,
Marco
Jun 3, 2015 01:06 PM | Chris Rorden
RE: Slice Direction
You will get this error for 2D slices. The issue is that DICOM is
specific about orientation of the slice, but due to the
implementation of different vendors it can be ambiguous regarding
the depth direction (essentially, a 2D slice does not have a depth)
and slice thickness (see links here http://stackoverflow.com/questions/14930...). For this reason, conversion tools compare the values of
successive 2D slices when building a 3D stack to ensure precise
calculations. This is usually not a problem for brain imaging as 3D
acquisitions are required for accurate motion correction and
normalization. I suspect you are seeing this message for your scout
scan or your unreconstructed data (which for SPECT would be
cylindrical).
In any case, you can always check these results by opening an image with SPM or MRIcroGL and making sure the L->R, A->P and S->I dimensions are correct.
In any case, you can always check these results by opening an image with SPM or MRIcroGL and making sure the L->R, A->P and S->I dimensions are correct.