This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: 1H Magnetic resonance spectroscopic imaging (1H MRSI) is a useful technique for measuring brain metabolites. Dualband spatial-spectral (SPSP) pulses have been designed at 3T for fully exciting the metabolites of interest, partially exciting water, while suppressing lipids. However, in these sequences, the 180 SPSP pulses must have nonlinear phase (along the spectral direction) in order to stay below RF peak power limits and consequently both 180 pulses in the PRESS excitation are relatively long. This limits TE to a minimum of 90 ms for the brain. In this study, the use of a PRESS sequence with only one dualband spatial-spectral linear phase 90 pulse and two standard spatial 180 pulses is proposed for brain MRSI. This sequence provides spectral selectivity while allowing significantly shorter echo times than existing SPSP PRESS sequences for the brain. Methods and Discussion: A linear phase 90 dualband SPSP pulse was designed using twenty one linear phase subpulses that could excite a slice as thin as 5 mm. The passband for the pulse encompassed choline at 3.2 ppm to NAA at 2.0 ppm while suppressing the lipids at 1.3 ppm and below. The partial water band was designed to excite 2% of the water signal at 4.7 ppm. The final pulse duration was 24 ms resulting in TE=60 ms. The dualband SPSP 90 pulse had very low ripple in the metabolite passband but considerable ripple in the partial water passband. However, since we are only using water as a frequency reference and not concerned with its magnitude, this ripple is tolerable. Phantom and in vivo studies demonstrate the new pulse sequence achieved the targeted design parameters. References: [1] Star-Lack JM, et al. Magn Reson Med 2000; 43:325-330. [2] Cunningham CH, et al. Magn Reson Med. 2005 May; 53(5):1033-9. [3] Barker PB, et al. Magn Reson Med. 2001 May;45(5):765-9. Acknowledgements: Lucas Foundation, NIH RR09784,

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR009784-12
Application #
7358768
Study Section
Special Emphasis Panel (ZRG1-SBIB-F (40))
Project Start
2006-06-01
Project End
2007-05-31
Budget Start
2006-06-01
Budget End
2007-05-31
Support Year
12
Fiscal Year
2006
Total Cost
$24,942
Indirect Cost
Name
Stanford University
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
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Bian, W; Tranvinh, E; Tourdias, T et al. (2016) In Vivo 7T MR Quantitative Susceptibility Mapping Reveals Opposite Susceptibility Contrast between Cortical and White Matter Lesions in Multiple Sclerosis. AJNR Am J Neuroradiol 37:1808-1815
Vos, Sjoerd B; Aksoy, Murat; Han, Zhaoying et al. (2016) Trade-off between angular and spatial resolutions in in vivo fiber tractography. Neuroimage 129:117-132

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