Dear Karen,
I'm pretty sure that number down to 0.4 mm can still be estimated pretty accurately in a realignment. A rigid realignment can be estimated very well over a large volume.
I'm not aware of a comparison of realignment techniques, especially at such small values.
Nonetheless, I'm pretty sure that if your voxels are 3x3x4 mm^3, you don't probably need realignement with a 0.4 mm accuracy to begin with.
Cheers,
Luca
________________________________________
Da: SPM (Statistical Parametric Mapping) <[log in to unmask]> per conto di Karsten Mueller <[log in to unmask]>
Inviato: mercoledì 19 ottobre 2016 16.47.48
A: [log in to unmask]
Oggetto: [SPM] Accuracy of 6 motion parameters with a big voxel size: 3x3x4 mm^3
Subject: Accuracy of 6 motion parameters with a big voxel size: 3x3x4 mm^3
Dear Colleagues,
I would like to ask you for your opinion about the SPM-Output including the 6 motion parameters (TXT-File from realignment) when using a BIG voxel size of 3x3x4 mm^3.
What is the accuracy of the numbers written in the txt-file?
While motion within the range of a half voxel length (around 1.5mm) may be a reliable number, values smaller than 0.4 mm (that would be smaller than 1/7 of a voxel length) have probably a low accuracy.
Does it make sense to discuss motion in the range between 0.0 and 0.4 mm when using voxels of 3x3x4 mm^3?
Are there comparisons between the SPM-values and a motion tracking system using such a big voxel size?
Thank you very much for your suggestions,
Best wishes,
Karsten
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