Tilted head positions can indeed cause segmentation problems. You can
use the adjustment described by Dana also to correct for the tilted head
(pitch/roll/yaw).
Don't forget to correct for this movement in your functional images, or
to coregister anatomy and functional images at the end again.
- Benjamin
Dana Perantie schrieb:
> Hi Youngbin,
>
> It’s difficult to say what is happening. Is it only a problem with this
> one subject, while segments of other subjects are fine? I find that if
> the head is tilted it doesn’t matter as long as the AC is set as the
> origin prior to segmenting. I have no idea if this is the problem, but
> it’s all I can think to suggest:
>
> When you Display the structural scan and go to coordinate (mm) 0 0 0 the
> crosshairs should land on the AC. If it does not, you can adjust the
> “right” “forward” “up” in the lower left of the Display and then
> “Reorient image” to make the AC the origin. Carlton Chu posted a script
> to do this automatically if you have a lot of images (auto_reorient.m).
>
> https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0810&L=SPM&P=R35554
> <https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0810&L=SPM&P=R35554>
>
>
>
> -Dana
>
>
>
> *From:* SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]]
> *On Behalf Of *Youngbin Kwak
> *Sent:* Sunday, May 03, 2009 4:53 PM
> *To:* [log in to unmask]
> *Subject:* [SPM] SPM5 segmentation
>
>
>
> Hi all,
>
>
>
> One of my subject's head position in the high resolution structural scan
> is not quite parallel to the AC-PC line (he lifted his chin up), and I
> think this causes problems such as when using segmentation. Even after
> coregistering it to his functional scans which are relatively well
> positioned, using segmenation option in SPM5 does not give any results
> for gray and white matter. Can someone help me out solve this issue?
>
> Thanks!
>
> Youngbin
>
--
Benjamin Bender
Abteilung Diagnostische und Interventionelle Neuroradiologie
Universitätsklinikum Tübingen
Hoppe-Seyler- Str. 3
72076 Tübingen
Tel. (07071) 29-85397
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