[Insight-users] Re:Registration

[Luis Ibanez]

Hi Srivalli,

Since you are using the CenteredAffineTransform, please
make sure that you initialize it by using the class:

   CenteredTransformInitializer

You will find examples on how to do this in the softwareguide

    http://www . itk . org/ItkSoftwareGuide . pdf


and the source code in

    Insight/Examples/Registration

Also, make sure that you define the array of optimizerScales.
It is fundamental to scale the translation paramters with
respect to the rotation (matrix components) parameters.
You will also find examples about this in the SoftwareGuide.


Regards,


   Luis


--------------
CSPL wrote:
> Dear Mr.Luis,
>  
>  ThankYou for your reply. I am enclosing the details about registration 
> components.
>  
> Transform : CenteredAffineTransform
> Optimizer : RegularStepGradientDescentOptimizer
> Metric :MattesMutualInformationImageToImageMetric
> Interpolation :LinearInterpolateImageFunction
> Registration Method : MultiResolutionImageRegistrationMethod
> Pyramid : RecursiveMultiResolutionPyramidImageFilter
>  
> 
> Regards,
> SriValli.
> Your reply:
> 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
>  
> My question:
> 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.