Dear SPM experts,
In the process of segmenting structural MRI scans I have encountered several strange problems.
I have added a screenshot of some of the (gray matter) segmentations. As you can see, some
scans appear to be almost empty, or have strange artificial stripes, or even have parts missing of
the brain.
Even though I understood that orientation and origin don't have to be exact, I experience that by
slightly changing the orientation or origin can results in very different kind of segmentations.
Sometimes one bad segmented scan will be perfectly fine after adjusting the origin only slightly
(+1 voxel up or to the right or 0.01 pitch, yaw or roll)
The scan's that were not segmented correctly don't have any visual anomalies that could explain
the flawed segmentation. (I have added a screenshot of those scans, same order as the segm.)
Which brings me to the following questions:
- Are the segmentations that were bad before, but after adjustment looked visually fine, trustworthy?
- Is there a way (without endlessly trying to adjust the origin and re segmenting) to "fix" the
segmentation of other scans.
The segmentation is done in SPM8 with the "segment" in the main menu, after applying non uniformity correction (Sled et al.)
Kindest regards,
Mireille Nieuwenhuis | Neuroimaging Research Group | Department of Psychiatry | University Medical Center Utrecht | Heidelberglaan 100, 3584 CX Utrecht, the Netherlands | E-mail: [log in to unmask] | Currently at UCL and IoP in London (till the end of july 2012)
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