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Hyperpolarized helium-3 diffusion ma...

Wang, Chengbo.

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Hyperpolarized helium-3 diffusion magnetic resonance imaging in human lungs.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Hyperpolarized helium-3 diffusion magnetic resonance imaging in human lungs./
作者:	Wang, Chengbo.
面頁冊數:	172 p.
附註:	Adviser: John P. Mugler, III.
Contained By:	Dissertation Abstracts International68-02B.
標題:	Engineering, Biomedical. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3251384

Hyperpolarized helium-3 diffusion magnetic resonance imaging in human lungs.
Wang, Chengbo.

Hyperpolarized helium-3 diffusion magnetic resonance imaging in human lungs. - 172 p.

Adviser: John P. Mugler, III.

Thesis (Ph.D.)--University of Virginia, 2007.

Overall, our results suggest that measuring 3He diffusion over both short and long time scales offers a valuable tool for characterizing the lung structure of subjects with severe asthma or COPD.Subjects--Topical Terms:

1017684
Engineering, Biomedical.

Hyperpolarized helium-3 diffusion magnetic resonance imaging in human lungs.
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035 $a (UMI)AAI3251384
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100 1 $a Wang, Chengbo. $3 1294735
245 1 0 $a Hyperpolarized helium-3 diffusion magnetic resonance imaging in human lungs.
300 $a 172 p.
500 $a Adviser: John P. Mugler, III.
500 $a Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1125.
502 $a Thesis (Ph.D.)--University of Virginia, 2007.
520 $a Overall, our results suggest that measuring 3He diffusion over both short and long time scales offers a valuable tool for characterizing the lung structure of subjects with severe asthma or COPD.
520 $a COPD and asthma are important lung diseases that have significant morbidity and mortality. Current methods for diagnosing and monitoring COPD and asthma are not sensitive enough. Hyperpolarized 3He magnetic MRI has been used to assess a number of lung diseases. The high diffusivity of 3He permits 3He diffusion MRI to be used to investigate various structural aspects of the lung at different time scales. Short-time-scale 3He diffusion MRI has proven to be sensitive to emphysematous changes. Preliminary results suggest that long-time-scale 3He diffusion MRI may offer improved sensitivity to emphysematous changes than the standard short-time-scale 3He diffusion MRI.
520 $a Several new MR pulse sequences based on stimulated echoes were developed to measure 3He diffusion for diffusion times on the order of a second. The basic equations governing the evolution of signals during these measurements were developed. Numerical simulations were performed to assess the sensitivity of the proposed methods to noise and to variations in experimental or physical parameters. In addition, measurements were made in a nearly-free-diffusion gas phantom and the results were compared with literature values.
520 $a Measurements in healthy subjects confirmed that 3He diffusion still strongly depends on the diffusion time for times on the order of a second, and that the ADC decreases by about 7 fold when the diffusion time is increased from 0.2 to 6 seconds. Reproducibility, anisotropy of diffusion values and the dependence on tag wavelength were characterized.
520 $a Experiments in COPD subjects proved that measurement of 3He diffusion in the long-time-scale is significantly more sensitive to early COPD changes than the standard measurement of 3He diffusion in the short-time-scale. Measurements in severe asthma subjects revealed large regional variations in long-time-scale ADC maps, while the corresponding short-time-scale ADC maps were more uniform, with small regional variations. There was good correlation between areas where long-time-scale ADC values increased and areas of low-density "air-trapping" seen on computed-tomography images.
590 $a School code: 0246.
650 4 $a Engineering, Biomedical. $3 1017684
650 4 $a Health Sciences, Radiology. $3 1019076
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710 2 0 $a University of Virginia. $3 645578
773 0 $t Dissertation Abstracts International $g 68-02B.
790 $a 0246
790 1 0 $a Mugler, John P., III, $e advisor
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3251384