[Insight-users] Problems related to registration

[Luis Ibanez]

Hi Srivalli,

Here are some of the points to check


0) Make sure that the pixel spacing
    and origin of your image are correctly
    set in millimeters.


1) What registration components are you
    using  ?

    - optimizer ?
    - metric    ?
    - transform ?


2) Connect an Observer to the optimizer
    and print out the metric value and
    the transform parameters as the registration
    progresses.

3) Plot the Metric values versus the number
    of iterations and evaluate how noisy the
    metric is, and how much it is increasing.


The plots of Metric and transform parameters
versus number of iterations are the best
guidance for determining how to tune the
parameters of a registration method.

Please provide more details about the components
you are combining.


Thanks


    Luis


-------------------
CSPL wrote:
> Dear Mr.Luis,
>  
>  I am working on medical image registration. I could get the single 
> modality image registration well.
> But,Facing problems in MultiModalityRegistration.
> In my application I have to register MR and SPECT volumes, MR as FIXED 
> and SPECT as MOVING.
> Both MR and SPECT are PreProcessed.
> MR is of size 256X256X120.
> Brain is extracted from skull in MR volume and the extracted brain is 
> used as FIXED.
> ITK Neighbourhoodconnected filter is used to extract object based on the 
> given seed point and threshold range.
>  
> SPECT is processed to make cubic voxels.
> Procesed to find the minimum dimension of SPECT  and creates a new 
> volume with all  dimensions equal to minimum dimension.
>  Inititally SPECT is of size 128X128X49.After processing it will become 
> 128X128X96.Voxel Width, Voxel Height and Voxel Depth will be same.
>  
> After preprocessing extracted brain and spect will be given as inputs 
> for registration.
>  
> To view the output of registration, I am merging SPECT with original MR 
> volume(includes both brain and skull) so that spect exactly fits in the 
> brain part.
> But, when I see the output spect is not positioning correctly.
> Sometimes I see that  middle slices are ok but,failing at last slices.
> I tried in many ways by chaning the parameters.
> I feel that registration depends on fixed and moving images. Parameter 
> tuning can be succes only if input images are correct.
> Can you please tell us what could be the reason to fail?
> I am doubt whether I am  wrong in giving input images or in tuning 
> parameters.
> Regards,
> Srivalli