Model for the correction of motion-induced phase errors in multishot diffusion-weighted-MRI of the head: are cardiac-motion-induced phase errors reproducible from beat-to-beat?
In diffusion-weighted imaging, multishot acquisitions are problematic due to intershot inconsistencies of the phase caused by motion during the diffusion-encoding gradients. A model for the motion-induced phase errors in diffusion-weighted-MRI of the brain is presented, in which rigid-body and nonrigid-body motion are separated. In the model, it is assumed that nonrigid-body motion is due to cardiac pulsation, and that the motion patterns are repeatable from beat-to-beat. To test the validity of this assumption, the repeatability of nonrigid-body motion-induced phase errors is quantified in three healthy volunteers. Nonrigid-body motion-induced phase was found to significantly correlate (P < 0.05) with pulse-oximeter waveforms in ~83% of the pixels tested across all slices and subjects.
Department of Radiology, Stanford University, Stanford, California, USA. rafaelo@stanford.edu
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O'Halloran
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Holdsworth
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Aksoy
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Bammer
D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D019416:Head Movements / Q000502:physiology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity