Data-driven Retrospective Correction of B1 Field Inhomogeneity in Fast Macromolecular Proton Fraction and R1 Mapping

2021 ◽  
pp. 1-1
Author(s):  
Vasily L. Yarnykh
Keyword(s):  
Data Driven ◽  
Field Inhomogeneity ◽  
B1 Field

Quantitative T1ρ imaging using phase cycling for B0 and B1 field inhomogeneity compensation

2011 ◽  
Vol 29 (5) ◽  
pp. 608-619 ◽  
Author(s):  
Weitian Chen ◽  
Atsushi Takahashi ◽  
Eric Han
Keyword(s):  
Field Inhomogeneity ◽  
Phase Cycling ◽  
B1 Field

scholarly journals Suppression of probe background signals via B1 field inhomogeneity

2011 ◽  
Vol 209 (2) ◽  
pp. 300-305 ◽  
Author(s):  
Jian Feng ◽  
Jeffrey A. Reimer
Keyword(s):  
Field Inhomogeneity ◽  
B1 Field

scholarly journals Transmit B1+ field inhomogeneity and T1estimation errors in breast DCE-MRI at 3 tesla

2013 ◽  
Vol 38 (2) ◽  
pp. 454-459 ◽  
Author(s):  
Kyunghyun Sung ◽  
Bruce L. Daniel ◽  
Brian A. Hargreaves
Keyword(s):  
3 Tesla ◽  
Field Inhomogeneity ◽  
Dce Mri ◽  
B1 Field

scholarly journals Using nutation-frequency-selective pulses to reduce radio-frequency field inhomogeneity in solid-state NMR

2020 ◽  
Author(s):  
Kathrin Aebischer ◽  
Nino Wili ◽  
Zdeněk Tošner ◽  
Matthias Ernst
Keyword(s):  
Solid State ◽  
Radio Frequency ◽  
Solid State Nmr ◽  
Sample Volume ◽  
Field Inhomogeneity ◽  
Spin Lock ◽  
Selective Pulses ◽  
Physical Volume ◽  
The Family ◽  
B1 Field

Abstract. Radio-frequency (rf) field inhomogeneity is a common problem in NMR which leads to non-ideal rotations of spins in parts of the sample. Often, a physical volume restriction of the sample is used to reduce the effects of rf-field inhomogeneity especially in solid-state NMR where spacers are inserted to reduce the sample volume to the centre of the coil. We show that band-selective pulses in the spin-lock frame can be used to apply B1-field selective inversions to spins that experience selected parts of the rf-field distribution. Any frequency band-selective pulse can be used for this purpose but we chose the family of I-BURP pulses (H. Geen, R. Freeman, Band-Selective Radiofrequency Pulses, J. Magn. Reson. 93 (1991) 93–141) for the measurements demonstrated here. As an example, we show that the implementation of such pulses improves homonuclear frequency-switched Lee-Goldburg decoupling in solid-state NMR.

The effect of B1 field inhomogeneity and the nonselective inversion profile on the kinetics of FAIR-based perfusion MRI

2005 ◽  
Vol 53 (6) ◽  
pp. 1355-1362 ◽  
Author(s):  
Janneke Schepers ◽  
Matthias J. P. van Osch ◽  
Lambertus W. Bartels ◽  
Sean N. Heukels ◽  
Max A. Viergever ◽  
...  
Keyword(s):  
Perfusion Mri ◽  
Field Inhomogeneity ◽  
B1 Field ◽  
Kinetics Of

scholarly journals The Influence of Radio-Frequency Transmit Field Inhomogeneities on the Accuracy of G-ratio Weighted Imaging

2021 ◽  
Vol 15 ◽  
Author(s):  
Tim M. Emmenegger ◽  
Gergely David ◽  
Mohammad Ashtarayeh ◽  
Francisco J. Fritz ◽  
Isabel Ellerbrock ◽  
...  
Keyword(s):  
White Matter ◽  
Radio Frequency ◽  
Dynamic Range ◽  
Volume Fraction ◽  
Statistical Parameter ◽  
Data Driven ◽  
Mapping Technique ◽  
Brain White Matter ◽  
B1 Field ◽  
G Ratio

G-ratio weighted imaging is a non-invasive, in-vivo MRI-based technique that aims at estimating an aggregated measure of relative myelination of axons across the entire brain white matter. The MR g-ratio and its constituents (axonal and myelin volume fraction) are more specific to the tissue microstructure than conventional MRI metrics targeting either the myelin or axonal compartment. To calculate the MR g-ratio, an MRI-based myelin-mapping technique is combined with an axon-sensitive MR technique (such as diffusion MRI). Correction for radio-frequency transmit (B1+) field inhomogeneities is crucial for myelin mapping techniques such as magnetization transfer saturation. Here we assessed the effect of B1+ correction on g-ratio weighted imaging. To this end, the B1+ field was measured and the B1+ corrected MR g-ratio was used as the reference in a Bland-Altman analysis. We found a substantial bias (≈-89%) and error (≈37%) relative to the dynamic range of g-ratio values in the white matter if the B1+ correction was not applied. Moreover, we tested the efficiency of a data-driven B1+ correction approach that was applied retrospectively without additional reference measurements. We found that it reduced the bias and error in the MR g-ratio by a factor of three. The data-driven correction is readily available in the open-source hMRI toolbox (www.hmri.info) which is embedded in the statistical parameter mapping (SPM) framework.

scholarly journals Using nutation-frequency-selective pulses to reduce radio-frequency field inhomogeneity in solid-state NMR

2020 ◽  
Vol 1 (2) ◽  
pp. 187-195
Author(s):  
Kathrin Aebischer ◽  
Nino Wili ◽  
Zdeněk Tošner ◽  
Matthias Ernst
Keyword(s):  
Solid State ◽  
Radio Frequency ◽  
Solid State Nmr ◽  
Sample Volume ◽  
Field Inhomogeneity ◽  
Spin Lock ◽  
Selective Pulses ◽  
Physical Volume ◽  
The Family ◽  
B1 Field

Abstract. Radio-frequency (rf) field inhomogeneity is a common problem in NMR which leads to non-ideal rotations of spins in parts of the sample. Often, a physical volume restriction of the sample is used to reduce the effects of rf-field inhomogeneity, especially in solid-state NMR where spacers are inserted to reduce the sample volume to the centre of the coil. We show that band-selective pulses in the spin-lock frame can be used to apply B1-field selective inversions to spins that experience selected parts of the rf-field distribution. Any frequency band-selective pulse can be used for this purpose, but we chose the family of I-BURP pulses (Geen and Freeman, 1991) for the measurements demonstrated here. As an example, we show that the implementation of such pulses improves homonuclear frequency-switched Lee–Goldburg decoupling in solid-state NMR.

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