[slicer-users] Comparing difference between two scans

Andriy Fedorov fedorov at bwh.harvard.edu
Fri Apr 16 16:18:40 EDT 2010


On Fri, Apr 16, 2010 at 14:57, Dominik Meier <meier at bwh.harvard.edu> wrote:
> - there's also the 'ChangeTracker'  module that provides different metrics
> based on deformation or intensity
> http://www.slicer.org/slicerWiki/index.php/Modules:ChangeTracker-Documentation-3.4

Murat,

If you end up using ChangeTracker, I would recommend that you first
register (rigidly, I assume) the images outside of ChangeTracker, and
then tell it to use the existing transform (this is a new feature of
3.5/3.6: http://wiki.slicer.org/slicerWiki/index.php/Modules:ChangeTracker-Documentation-3.6),
and turn off region registration.

ChangeTracker can try to estimate volume change based on non-rigid
deformation, and/or based on intensity differences. You will need to
provide the segmentation of the object in the first scan. Note, that
deformable metric of ChangeTracker uses demons registration. If the
volumes are large, this may fail or take too long to complete, so your
only option may be intensity metric.

If you can share your data, I have another implementation of change
detection, which is based on tracking the object surface. It is not
part of Slicer at this time, but it should be straightforward to try
it on your data. Let me know if you would like to do this.

Andriy Fedorov



> Best,
> Dominik
> ______________________________________________
> DOMINIK MEIER, PH.D.
> Brigham & Women's Hospital / Harvard Medical School
> 221 Longwood Avenue, RF396, Boston, MA 02115
>
> On Apr 16, 2010, at 2:30 PM, Murat Maga wrote:
>
> Hi,
> This is not really a Slicer question, but I thought I might get some
> pointers towards the right direction.
> We would like to compare scans from two different microCT scanners.
> These are not medical scanners and are not calibrated to any standard.
> We want to measure how much difference there is at the end by using the
> standard procedures of the two facilities. For that, we thought of
> looking at the trabecular bone structural parameter estimates, and
> measure the extend they differ (if they do at all).
> But given that we will be scanning identical specimen, I thought there
> might be a better measure of overall difference. In theory, these two
> datasets should register perfectly and any difference can be attributed
> to the difference in scan quality and/or reconstruction parameters. But
> I don't know how we can convert this difference in a some kind of metric.
> Any suggestions?
> M
> --
> A. Murat Maga, PhD
> Senior Fellow
> UW Pediatrics
> Division of Craniofacial Medicine
> 1959 NE Pacific St RR234
> Seattle, WA 98195
> 206-616 9703
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