Echo Planar Imaging
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Echo Planar Imaging
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Author : Franz Schmitt
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Echo Planar Imaging written by Franz Schmitt and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Medical categories.
"Dost thou love life? Then do not squander time, for that's the stuff life is made oj': Benjamin Franklin This book describes the technical principles and applications of echo-planar imaging (EPI) which, as much as any other technique, has shaped the develop ment of modern magnetic resonance imaging (MRI). The principle of EPI, namely, the acquisition of multiple nuclear magnetic resonance echoes from a single spin excitation, has made it possible to shorten the previously time-con suming MRI data acquisition from minutes to much less than a second. Interest ingly, EPI is one of the oldest MRI techniques, conceived in 1976 by Sir Peter Mansfield only 4 years after the initial description of the principles of MRI. One of the inventors of MRI himself, Mansfield realized that fast data acquisition would be paramount in bringing medical applications of MRI to full fruition. The technological challenges in implementing EPI, however, were formidable. Until the end of the 1980s few people believed that EPI would be clinically useful, since its complexity was far greater than that of "conventional" MRI methods.
Echo Planar Imaging Artifact Correction With Parallel Imaging
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Author : Bin Xie
language : en
Publisher: Open Dissertation Press
Release Date : 2017-01-26
Echo Planar Imaging Artifact Correction With Parallel Imaging written by Bin Xie and has been published by Open Dissertation Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-26 with Echo-planar imaging categories.
This dissertation, "Echo Planar Imaging Artifact Correction With Parallel Imaging" by Bin, Xie, 解斌, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Echo planar imaging (EPI) is a fast imaging technique that has been widely used in various MRI applications, such diffusion, perfusion and functional magnetic resonance imaging (fMRI). However, the EPI image quality is intrinsically hindered by three major artifacts, i.e., Nyquist ghost, geometric distortion and fat residue. The main objective of this dissertation is to investigate and develop novel methods to correct different EPI artifacts using parallel imaging. Firstly, a new Nyquist ghost and geometric distortion correction method using parallel imaging was proposed in EPI. This method calibrates the parallel imaging from two frames of EPI acquired with different phase labels. Then Nyquist ghost is subsequently removed by reconstructing images from only positive or negative echoes. Meanwhile, this phase labeling strategy shifts the TE of the second frame and allows the B0 field map generation from positive and negative images for distortion correction. The phantom results at 7T and 3T demonstrated that our method could greatly reduce Nyquist ghost even under oblique imaging and poor eddy current conditions, yielding significant improvements over the existing reference scan and image entropy minimization methods, and eliminate the geometric distortion simultaneously. The phantom results indicated that the SNR efficiency was largely preserved while the fMRI results showed no apparent degradation of temporal resolution. Secondly, in order to further improve the SNR performance of parallel imaging in Nyquist ghost correction, a new method which incorporates phase error correction with sensitivity encoding (SENSE) was proposed. This method reconstructs two Nyquist ghost free images from positive or negative echo, and then estimates a phase error map from these two images. Phase error correction is subsequently incorporated into SENSE to reconstruct the final Nyquist ghost free images. Results from phantom and human brain experiments demonstrated that this method was as robust as the other parallel imaging based Nyquist ghost correction techniques even under oblique imaging and poor eddy current conditions. Moreover, SNR measurements in both phantom and in vivo studies suggested that this method did not suffer from noise amplification and provided larger signal-to-noise ratio (SNR) than the others similar parallel imaging based Nyquist ghost correction techniques. Lastly, the parallel imaging was applied to separate water and fat signal in EPI images. This method utilizes the intrinsic chemical shift property of fat. It treats the water and shifted fat signal in composite EPI images as two simultaneously excited images, which are separated by parallel imaging. Two parallel imaging reconstruction algorithms were applied and evaluated for water and fat separation. The human brain EPI results demonstrated the feasibility of using parallel imaging to separate water and fat signal by both algorithms. This method was further applied to brain and liver diffusion weighted imaging, and the results demonstrated it can be used to remove the undesired fat residual signal. In summary, these studies have demonstrated parallel imaging can be used for EPI artifacts correction and benefit EPI-based applications. Subjects: Echo-planar imaging
Echo Planar Imaging
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Author : David M. Weber
language : en
Publisher:
Release Date : 1993
Echo Planar Imaging written by David M. Weber and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Magnetic resonance imaging categories.
Echo Planar Imaging Artifact C
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Author : Bin Xie
language : en
Publisher: Open Dissertation Press
Release Date : 2017-01-26
Echo Planar Imaging Artifact C written by Bin Xie and has been published by Open Dissertation Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-26 with Technology & Engineering categories.
This dissertation, "Echo Planar Imaging Artifact Correction With Parallel Imaging" by Bin, Xie, 解斌, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Echo planar imaging (EPI) is a fast imaging technique that has been widely used in various MRI applications, such diffusion, perfusion and functional magnetic resonance imaging (fMRI). However, the EPI image quality is intrinsically hindered by three major artifacts, i.e., Nyquist ghost, geometric distortion and fat residue. The main objective of this dissertation is to investigate and develop novel methods to correct different EPI artifacts using parallel imaging. Firstly, a new Nyquist ghost and geometric distortion correction method using parallel imaging was proposed in EPI. This method calibrates the parallel imaging from two frames of EPI acquired with different phase labels. Then Nyquist ghost is subsequently removed by reconstructing images from only positive or negative echoes. Meanwhile, this phase labeling strategy shifts the TE of the second frame and allows the B0 field map generation from positive and negative images for distortion correction. The phantom results at 7T and 3T demonstrated that our method could greatly reduce Nyquist ghost even under oblique imaging and poor eddy current conditions, yielding significant improvements over the existing reference scan and image entropy minimization methods, and eliminate the geometric distortion simultaneously. The phantom results indicated that the SNR efficiency was largely preserved while the fMRI results showed no apparent degradation of temporal resolution. Secondly, in order to further improve the SNR performance of parallel imaging in Nyquist ghost correction, a new method which incorporates phase error correction with sensitivity encoding (SENSE) was proposed. This method reconstructs two Nyquist ghost free images from positive or negative echo, and then estimates a phase error map from these two images. Phase error correction is subsequently incorporated into SENSE to reconstruct the final Nyquist ghost free images. Results from phantom and human brain experiments demonstrated that this method was as robust as the other parallel imaging based Nyquist ghost correction techniques even under oblique imaging and poor eddy current conditions. Moreover, SNR measurements in both phantom and in vivo studies suggested that this method did not suffer from noise amplification and provided larger signal-to-noise ratio (SNR) than the others similar parallel imaging based Nyquist ghost correction techniques. Lastly, the parallel imaging was applied to separate water and fat signal in EPI images. This method utilizes the intrinsic chemical shift property of fat. It treats the water and shifted fat signal in composite EPI images as two simultaneously excited images, which are separated by parallel imaging. Two parallel imaging reconstruction algorithms were applied and evaluated for water and fat separation. The human brain EPI results demonstrated the feasibility of using parallel imaging to separate water and fat signal by both algorithms. This method was further applied to brain and liver diffusion weighted imaging, and the results demonstrated it can be used to remove the undesired fat residual signal. In summary, these studies have demonstrated parallel imaging can be used for EPI artifacts correction and benefit EPI-based applications. Subjects: Echo-planar imaging
Echo Planar Imaging
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Author : David M. Weber
language : en
Publisher:
Release Date : 1995
Echo Planar Imaging written by David M. Weber and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Magnetic resonance imaging categories.
Diffusion Weighted Magnetic Resonance Imaging With Readout Segmented Echo Planar Imaging
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Author : Stephen Robert Frost
language : en
Publisher:
Release Date : 2012
Diffusion Weighted Magnetic Resonance Imaging With Readout Segmented Echo Planar Imaging written by Stephen Robert Frost and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
A Computer Simulation For The Image Reconstruction Of Interleaved Echo Planar Magnetic Resonance Scans
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Author : Jonathan Matthew Bronstein
language : en
Publisher:
Release Date : 1998
A Computer Simulation For The Image Reconstruction Of Interleaved Echo Planar Magnetic Resonance Scans written by Jonathan Matthew Bronstein and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.
Optimization Of Echo Planar Imaging Technique And Applications To Functional Studies On Conscious Rabbits
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Author : Nan-kuei Chen
language : en
Publisher:
Release Date : 2001
Optimization Of Echo Planar Imaging Technique And Applications To Functional Studies On Conscious Rabbits written by Nan-kuei Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Echo planar imaging (EPI) is one of the fastest MR imaging sequences, and is appropriate for functional MRI (fMRI) studies because of its high temporal resolution and sensitivity to BOLD effect. However, EPI data is always degraded by various artifacts due to off-resonance factors. EPI artifacts need to be removed before the EPI based fMRI data can be correctly interpreted.
Spin Preparation Sequences For Echo Planar Imaging
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Author : Mark Roger Symms
language : en
Publisher:
Release Date : 1991
Spin Preparation Sequences For Echo Planar Imaging written by Mark Roger Symms and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with categories.
Single Shot Multi Echo Sensitivity Encoded Echo Planar Imaging With Application To Investigating Temporal Correlations In Functional Magnetic Resonance Imaging
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Author : Callen N. Johnson
language : en
Publisher:
Release Date : 2013
Single Shot Multi Echo Sensitivity Encoded Echo Planar Imaging With Application To Investigating Temporal Correlations In Functional Magnetic Resonance Imaging written by Callen N. Johnson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Echo-planar imaging categories.