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Prepolarized MRI: Development and ap...

Ungersma, Sharon E.

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Prepolarized MRI: Development and applications.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Prepolarized MRI: Development and applications./
作者:	Ungersma, Sharon E.
面頁冊數:	123 p.
附註:	Adviser: Albert Macovski.
Contained By:	Dissertation Abstracts International67-05B.
標題:	Biophysics, Medical. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3219400
ISBN:	9780542708343

Prepolarized MRI: Development and applications.
Ungersma, Sharon E.

Prepolarized MRI: Development and applications. - 123 p.

Adviser: Albert Macovski.

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

Prepolarized magnetic resonance imaging (PMRI) is a low-cost alternative to conventional MRI that retains flexible soft-tissue contrast, while reducing the capital cost of a scanner from &sim;

ISBN: 9780542708343Subjects--Topical Terms:

1017681
Biophysics, Medical.

Prepolarized MRI: Development and applications.
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520 $a Prepolarized magnetic resonance imaging (PMRI) is a low-cost alternative to conventional MRI that retains flexible soft-tissue contrast, while reducing the capital cost of a scanner from &sim; $1 million to &sim; $1 00,000. Instead of the static high-field superconducting magnet used in conventional MRI, PMRI uses two pulsed electromagnets for the two separate aspects of the MR imaging process: sample polarization and signal acquisition. This decoupling of the magnetic fields for polarization and data acquisition allows PMRI to retain the theoretical SNR of the higher polarization field, while adding the advantages of a low-field signal readout. These advantages include less acoustic noise, less RF heating of the patient, reduced susceptibility artifacts, and the possibility of creating image contrast using the flexible choice of field strength.
520 $a We have used PMRI to implement a novel form of contrast called T1 dispersion imaging, which takes advantage of the dependence of T1 on magnetic field strength. We polarize the sample at high field, then allow the sample magnetization to decay at an intermediate "evolution" field before acquiring the image at low field. The difference between images collected with different evolution field strengths can highlight tissues with significant T1 variation. In particular, tissues with high protein content, such as muscle tissue, exhibit rapid changes in their T1 due to cross-relaxation with nitrogen nuclei in protein backbones. We have created in vivo images with T1 dispersion contrast in the wrist and foot, showing contrast between healthy muscle tissue and fat. This technique may be useful for monitoring the degradation of muscle tissue in the extremities caused by diseases such as diabetes.
520 $a The T1 dispersion imaging technique can also be used over a larger field range to detect more general trends in the dependence of T1 on magnetic field strength. Gadolinium contrast agents have a significant slope to their T1 dispersion curves, while fat has a fairly flat dispersion curve even up to 0.5 T; thus, the T1 dispersion technique can be used to suppress fat signal while retaining contrast-enhanced signal. We present proof-of-concept images showing good fat suppression in the wrist while retaining strong signal from gadolinium solutions.
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