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Studies of magnetic susceptibility a...

Zhao, Yansong.

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Studies of magnetic susceptibility artifacts in magnetic resonance imaging.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Studies of magnetic susceptibility artifacts in magnetic resonance imaging./
Author:	Zhao, Yansong.
Description:	142 p.
Notes:	Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 2109.
Contained By:	Dissertation Abstracts International67-04B.
Subject:	Engineering, Biomedical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3214335
ISBN:	9780542658266

Studies of magnetic susceptibility artifacts in magnetic resonance imaging.
Zhao, Yansong.

Studies of magnetic susceptibility artifacts in magnetic resonance imaging. - 142 p.

Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 2109.

Thesis (Ph.D.)--Yale University, 2006.

The use of high magnetic fields for in vivo magnetic resonance greatly benefits neuroimaging, cardiac imaging and in vivo MR spectroscopy by higher signal-to-noise ratio, better BOLD contrast, and increased spectral resolution. However, magnetic field inhomogeneity increases with field strength, leads to more severe magnetic susceptibility artifacts that restrict many pulse sequences, particularly those widely-used fast T2*-sensitive imaging techniques.

ISBN: 9780542658266Subjects--Topical Terms:

1017684
Engineering, Biomedical.

Studies of magnetic susceptibility artifacts in magnetic resonance imaging.
LDR:03210nmm 2200325 4500 001 1828903
005 20071023113046.5
008 130610s2006 eng d
020 $a 9780542658266
035 $a (UMI)AAI3214335
035 $a AAI3214335
040 $a UMI $c UMI
100 1 $a Zhao, Yansong. $3 1917781
245 1 0 $a Studies of magnetic susceptibility artifacts in magnetic resonance imaging.
300 $a 142 p.
500 $a Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 2109.
500 $a Adviser: John C. Gore.
502 $a Thesis (Ph.D.)--Yale University, 2006.
520 $a The use of high magnetic fields for in vivo magnetic resonance greatly benefits neuroimaging, cardiac imaging and in vivo MR spectroscopy by higher signal-to-noise ratio, better BOLD contrast, and increased spectral resolution. However, magnetic field inhomogeneity increases with field strength, leads to more severe magnetic susceptibility artifacts that restrict many pulse sequences, particularly those widely-used fast T2*-sensitive imaging techniques.
520 $a This thesis investigates the susceptibility artifacts in MRI, specifically, image distortions and signal losses resulting from static susceptibility differences and signal fluctuations from dynamic respiratory effects. The mechanism by which field inhomogeneities affect image is presented. Field inhomogeneities and artifacts that arise from changing the chest volume and/or overall air susceptibility during abdominal breathing are calculated using a magnetic field calculator and two sets of digital phantoms. Respiration-induced signal fluctuations are serious artifacts in functional images that affect the sensitivity of BOLD-fMRI. They are largely the result of intravoxel dephasing and are severe in inferior parts of the brain as well as in EPI experiments with long echo times.
520 $a High order dynamic shimming is capable to reduce both subject-induced and respiration-induced susceptibility artifacts. Benefits and challenges of high order dynamic shimming are demonstrated with computer simulations using real image data. Geometric distortions and signal intensities for different degrees of dynamic shimming are simulated and the results are compared with the images obtained with a conventional shimming technique.
520 $a Another contribution of this thesis is a fast, high resolution B 0 mapping method that takes advantage of the multi-shots fast spin echo sequence. It is faster and less sensitive to signal losses than the conventional gradient echo technique, and has the ability to acquire high resolution field maps to accurately describe the field inhomogeneities. The sequence has been successfully implemented on various systems. A MATLAB based automatic shimming tool that utilizes such fast field mapping method has been developed to locally correct field inhomogeneities up to the third order.
590 $a School code: 0265.
650 4 $a Engineering, Biomedical. $3 1017684
650 4 $a Engineering, Electronics and Electrical. $3 626636
650 4 $a Health Sciences, Radiology. $3 1019076
690 $a 0541
690 $a 0544
690 $a 0574
710 2 0 $a Yale University. $3 515640
773 0 $t Dissertation Abstracts International $g 67-04B.
790 1 0 $a Gore, John C., $e advisor
790 $a 0265
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3214335