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Lucilio Cordero-Grande and Carlos Alberola -López LPI, University of Valladolid ( Spain ). EXTENDING HARP IMAGING BY ACQUIRING AN OVERDETERMINED SET OF STRIPES. Computer No.: 10 . Introduction (I). MR tagging: tracking of material points through time. Introduction (II).
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Lucilio Cordero-Grande and Carlos Alberola-López LPI, University of Valladolid (Spain) EXTENDING HARP IMAGING BY ACQUIRING AN OVERDETERMINED SET OF STRIPES Computer No.: 10
Introduction (I) • MR tagging: tracking of material points through time Extending HARP imaging by acquiring an overdetermined set of stripes
Introduction (II) • Harmonic Phase (HARP) method for MR tagging • Dense reconstruction of the deformation gradient tensor • Prone to noise and phase interferences • Overdetermined set of stripes (~DiffusionWeightedImaging) Extending HARP imaging by acquiring an overdetermined set of stripes
Method (I) • HARP image: • Wave vector: • 2D (forsimplicity): • Matrixform: • (Spatial) deformationgradient tensor: Extending HARP imaging by acquiring an overdetermined set of stripes
Method (II) • HARP: [1] • Matrixform: [1] N.F. Osman, et alt. Imagingheartmotionusingharmonicphase MRI. IEEE TMI, 19(3): 186-202, 2000 Extending HARP imaging by acquiring an overdetermined set of stripes
Method (III) • LS estimation: • LAD estimation: ( ) • Local phaseWindowed Fourier Transform (WFT) [2] [2] L. Cordero-Grande et alt. Improvingharmonicphaseimagingbythewindowed Fourier transform. IEEE ISBI, 520-523, 2011 Extending HARP imaging by acquiring an overdetermined set of stripes
Results (I) • Simulateddeformation [3] appliedto a real image • Estimate • Mean FröbeniusNorm Error (FNE): • [3] M. Marinelli et alt. Automaticfilterdesign in HARP analysis of taggedmagneticresonanceimages. IEEE ISBI, 1429-1432, 2008. Extending HARP imaging by acquiring an overdetermined set of stripes
Results (II) Extending HARP imaging by acquiring an overdetermined set of stripes
Results (III) Extending HARP imaging by acquiring an overdetermined set of stripes
Results (IV) Extending HARP imaging by acquiring an overdetermined set of stripes
Results (V) • LAD betterthan LS for • Overdetermined HARP (O-HARP) using LAD betterthan HARP for • Relativedecrease in mean FNE of a 55% for Extending HARP imaging by acquiring an overdetermined set of stripes
Results (VI) Extending HARP imaging by acquiring an overdetermined set of stripes
Results (VII) • O-HARP: robustness • WFT-HARP: precision Extending HARP imaging by acquiring an overdetermined set of stripes
Conclusions • Acquisition of overdetermined set of stripes • Validationwithsynthetic data • New oportunitiesfor HARP imagingif: • Usingmodernacquisitiontechniques • Acquiringreducedsubset of k-space • Applicationto DENSE oreven PC Extending HARP imaging by acquiring an overdetermined set of stripes