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New Fourier-space sampling methods f...

Tsai, Chi-Ming.

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New Fourier-space sampling methods for fast magnetic resonance imaging and flow quantification.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	New Fourier-space sampling methods for fast magnetic resonance imaging and flow quantification./
Author:	Tsai, Chi-Ming.
Description:	110 p.
Notes:	Adviser: Dwight G. Nishimura.
Contained By:	Dissertation Abstracts International62-10B.
Subject:	Engineering, Electronics and Electrical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3028189
ISBN:	0493404767

New Fourier-space sampling methods for fast magnetic resonance imaging and flow quantification.
Tsai, Chi-Ming.

New Fourier-space sampling methods for fast magnetic resonance imaging and flow quantification. - 110 p.

Adviser: Dwight G. Nishimura.

Thesis (Ph.D.)--Stanford University, 2001.

Magnetic resonance imaging (MRI) has become a popular and effective diagnostic tool in hospitals since its initial clinical use in the early 1980s. MRI can provide not only <italic>in vivo</italic> morphological images but also physiological information such as blood flow velocity. The raw signals acquired from an MR scanner are usually interpreted as samples in Fourier space or so-called <italic> k</italic>-space. This thesis introduces new <italic>k</italic>-space sampling schemes for significantly reducing the scan times for general imaging and for flow quantification.

ISBN: 0493404767Subjects--Topical Terms:

626636
Engineering, Electronics and Electrical.

New Fourier-space sampling methods for fast magnetic resonance imaging and flow quantification.
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020 $a 0493404767
035 $a (UnM)AAI3028189
035 $a AAI3028189
040 $a UnM $c UnM
100 1 $a Tsai, Chi-Ming. $3 1256210
245 1 0 $a New Fourier-space sampling methods for fast magnetic resonance imaging and flow quantification.
300 $a 110 p.
500 $a Adviser: Dwight G. Nishimura.
500 $a Source: Dissertation Abstracts International, Volume: 62-10, Section: B, page: 4702.
502 $a Thesis (Ph.D.)--Stanford University, 2001.
520 $a Magnetic resonance imaging (MRI) has become a popular and effective diagnostic tool in hospitals since its initial clinical use in the early 1980s. MRI can provide not only <italic>in vivo</italic> morphological images but also physiological information such as blood flow velocity. The raw signals acquired from an MR scanner are usually interpreted as samples in Fourier space or so-called <italic> k</italic>-space. This thesis introduces new <italic>k</italic>-space sampling schemes for significantly reducing the scan times for general imaging and for flow quantification.
520 $a The first scheme is a variable-density sampling method which samples the high-spatial-frequency regions with a sampling density lower than that required by the well-known Nyquist sampling theorem. Although aliasing artifacts occur in the image, they can be diffuse and negligible compared to random noise if the sampling positions are adequately arranged. This method is particularly important for fast cardiovascular imaging where the scan time is limited by cardiac and respiratory motion.
520 $a The second sampling method slightly offsets the center of spiral trajectories so that the off-centered spiral trajectories are insensitive to the timing mis-registration between gradient and data acquisition systems of the MRI scanner. The timing error can cause shading artifact in spiral images and results in significant errors in quantitative applications such as flow quantification. This off-centered spiral trajectory is a simple but robust method to solve the timing problem.
520 $a Lastly a new flow quantification method based on Fourier velocity encoding is presented to overcome the notorious partial volume effects associated with conventional phase contrast methods. A new analysis framework is proposed to estimate the flow rate from low-spatial resolution and low-velocity-resolution velocity images which can be obtained in very short scan times. This method can extend the application of MR flow quantification to smaller vessels.
520 $a The concepts introduced in this thesis relieve MRI users from traditional thinking barriers such as Nyquist sampling criteria and partial volume effects. These concepts will stimulate more theoretical research in Fourier-space sampling and facilitate more clinical applications by reducing the scan time.
590 $a School code: 0212.
650 4 $a Engineering, Electronics and Electrical. $3 626636
650 4 $a Health Sciences, Radiology. $3 1019076
690 $a 0544
690 $a 0574
710 2 0 $a Stanford University. $3 754827
773 0 $t Dissertation Abstracts International $g 62-10B.
790 $a 0212
790 1 0 $a Nishimura, Dwight G., $e advisor
791 $a Ph.D.
792 $a 2001
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3028189