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In-Plane Motion Correction in Reconstruction of non-Cartesian 3D-functional MRI
Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
2011 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Korrigering av 2D-rörelser vid rekonstruktion av icke-kartesisk 3D funktionell MRI (Swedish)
Abstract [en]

When patients move during an MRI examination, severe artifacts arise in the reconstructed image and motion correction is therefore often desired. An in-plane motion correction algorithm suitable for PRESTO-CAN, a new 3D functional MRI method where sampling of k-space is radial in kx-direction and kz-direction and Cartesian in ky-direction, was implemented in this thesis work.

Rotation and translation movements can be estimated and corrected for sepa- rately since the magnitude of the data is only affected by the rotation. The data were sampled in a radial pattern and the rotation was estimated by finding the translation in angular direction using circular correlation. Correlation was also used when finding the translation in x-direction and z-direction.

The motion correction algorithm was evaluated on computer simulated data, the motion was detected and corrected for, and this resulted in images with greatly reduced artifacts due to patient movements. 

Abstract [sv]

När patienter rör sig under en MRI-undersökning uppstår artefakter i den rekonstruerande bilden och därför är det önskvärt med rörelsekorrigering. En 2D- rörelsekorrigeringsalgoritm som är anpassad för PRESTO-CAN har tagits fram. PRESTO-CAN är en ny fMRI-metod för 3D där samplingen av k-rummet är radiell i (kx,kz)-planet och kartesisk i ky-riktningen.

Rotations- och translationsrörelser kan estimeras separat då magnituden av signalen bara påverkas av rotationsrörelser. Eftersom data är samplat radiellt kan rotationen estimeras genom att hitta translationen i vinkelled med hjälp av cirkulär korrelation. Korrelation används även för att hitta translationen i i x- och z-riktningen. Test på simulerat data visar att rörelsekorrigeringsalgoritmen både detekterar och korrigerar för rörelser vilket leder till bilder med mycket mindre rörelseartefakter. 

Place, publisher, year, edition, pages
2011. , 62 p.
Keyword [en]
MRI, fMRI, PRESTO-CAN, Motion Correction, Radial Sampling Pattern, Fourier domain, Circular Correlation, Gridding Reconstruction
National Category
Medical Image Processing
URN: urn:nbn:se:liu:diva-72056ISRN: LiTH-ISY-EX--11/4480--SEOAI: diva2:456354
Subject / course
Computer Vision Laboratory
Available from: 2011-11-14 Created: 2011-11-14 Last updated: 2012-05-30Bibliographically approved

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Computer VisionThe Institute of Technology
Medical Image Processing

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