Abstract/Details

Power spectral density imaging to expand the Nyquist limit


2000 2000

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Abstract (summary)

Power spectral density imaging (PSDI), a new Magnetic Resonance Imaging (MRI) method, is introduced for the unaliasing of high frequency signal components which are usually mixed with the low frequency components in conventional MRI. In PSDI, k-space is scanned in several different ways, so the temporal and spatial components are aliased in different patterns. With the correct reconstruction, the power spectral density for each pixel is acquired with a much higher Nyquist frequency limit than could be otherwise achieved. In two-spatial-dimension (2D) PSDI, the Nyquist limit is determined by the time spent scanning every kx line. In the case of three-spatial-dimension (3D) PSDI, it is the time spent on scanning every (kx, ky) plane which determines the limit. Signals of full-brain functional MRI (FMRI) and functional connectivity studies are always contaminated with temporally aliased respiratory and cardiac signals, which are caused by hardware limitations on the TR time. With a higher Nyquist limit, PSDI can increase the accuracy of function detection in FMRI and functional connectivity studies by elimination of the contamination from the cardiac and respiratory signals. Conversely, unambiguous detection of the cardiac-band signal fluctuations could provide a new type of MR angiography. The tradeoff of this method is that only statistics can be acquired for each pixel, such as the mean and the power spectral density. In addition, a relatively long time is required for the collection of all the required data.

Indexing (details)


Subject
Biophysics;
Biomedical research
Classification
0760: Biophysics
0541: Biomedical research
Identifier / keyword
Applied sciences; Biological sciences; Cardiac signals; High-frequency signal components; Nyquist limit; Power spectral density imaging; Respiratory signals; Signal fluctuations
Title
Power spectral density imaging to expand the Nyquist limit
Author
Bennett, Raoqiong
Number of pages
140
Publication year
2000
Degree date
2000
School code
0495
Source
DAI-B 62/03, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780493167572, 0493167579
Advisor
Cox, Robert W.
University/institution
The Medical College of Wisconsin
University location
United States -- Wisconsin
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3007629
ProQuest document ID
304660105
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304660105/abstract
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