Quality ImprovementsQuality Improvementsfor Multi-Modal Neuroimagingfor Multi-Modal Neuroimaging
Mika SeppäMika Seppä
Brain Research Unit / LTLBrain Research Unit / LTLAMI-CentreAMI-Centre
Helsinki University of TechnologyHelsinki University of Technology
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1. Registration
2. Resampling
3. Visualization
3 central stages:
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Match metricMatch metric Single-modal registrationSingle-modal registration
– sum of squared differencessum of squared differences Multi-modal registrationMulti-modal registration
– mutual informationmutual information
1. Registration1. Registration
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MI artifactsMI artifacts
Images alignedImages aligned Same pixel/voxel Same pixel/voxel
sizessizes
Registration biasRegistration bias Local maximaLocal maxima
Continuous samplingContinuous sampling– higher-order methodhigher-order method
offset (pixels)
MI
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2. Resampling2. Resampling
Very common operationVery common operation– geom. correction, motion correction, group geom. correction, motion correction, group
average etc.average etc.
15 xSNR = 10*log10(s2/e2)
...
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Two-stage resamplingTwo-stage resamplingSN
R (d
B)
Time (ms)
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3. Visualization3. Visualization
0.1-5 fps
800 fps
120 fps
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Seppä (2007). On continuous sampling and sub-Seppä (2007). On continuous sampling and sub-sample accuracy in mutual-information registration. sample accuracy in mutual-information registration.
TKK ReportTKK Report, TKK-KYL-017., TKK-KYL-017.
Seppä (2007). High-quality two-stage resampling for 3-Seppä (2007). High-quality two-stage resampling for 3-D volumes in medical imaging. D volumes in medical imaging. Medical Image Medical Image
AnalysisAnalysis, 11:346-360., 11:346-360.
Seppä, Hämäläinen (2005). Visualizing human brain Seppä, Hämäläinen (2005). Visualizing human brain surface from T1-weighted MR images using texture-surface from T1-weighted MR images using texture-
mapped triangle meshes. mapped triangle meshes. NeuroImageNeuroImage, 26:1-12., 26:1-12.
Hiltunen, Suortti, Arvela, Seppä, Joensuu, Hari (2005). Hiltunen, Suortti, Arvela, Seppä, Joensuu, Hari (2005). Diffusion tensor imaging and tractography of distal Diffusion tensor imaging and tractography of distal peripheral nerves at 3 T. peripheral nerves at 3 T. Clinical NeurophysiologyClinical Neurophysiology, ,
116:2315-2323.116:2315-2323.
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