Constrained Source Space MR Spectroscopy: Multiple Voxels, No Gradient Readout

Landheer, Karl; Sahgal, Arjun; Das, Sandhitsu R.; Graham, Simon J.

doi:10.3174/ajnr.a4319

Cited by 5 publications

(11 citation statements)

References 26 publications

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“…Thus, for many pulse sequences there can be found examples in the literature which do not crush all unwanted coherence pathways. For an uncoupled spin ½ particle, ignoring the crushing effects of the slice‐select gradients and pulse profiles (which are explored further in the Discussion), it can be shown that the crusher scheme for PRESS used by Landheer et al does not crush the unwanted stimulated echo, a scheme for sLASER by Scheenen et al does not suppress 26 unwanted pathways, another scheme for sLASER by Boer et al does not suppress 2 unwanted pathways, a scheme for MEGA‐sLASER by Andreychenko et al does not suppress 8 unwanted pathways, and a separate scheme for MEGA‐sLASER by Prinsen et al does not suppress the same 8 unwanted pathways, a scheme for MEGA‐LASER by Bogner et al does not suppress 2 unwanted pathways, a scheme by Near et al for MEGA‐SPECIAL does not suppress 2 unwanted pathways, and schemes by Lin et al for J‐resolved LASER and J‐resolved sLASER do not suppress 18 and 2 unwanted pathways, respectively.…”

Section: Introductionmentioning

confidence: 99%

Dephasing optimization through coherence order pathway selection (DOTCOPS) for improved crusher schemes in MR spectroscopy

Landheer

Juchem

2018

Magnetic Resonance in Med

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Purpose To develop an algorithm which can robustly eliminate all unwanted coherence pathways for an arbitrary magnetic resonance spectroscopy experiment through the adjustment of the relative amplitudes of crusher gradients, thereby reducing the effects of spurious echoes and mislocalization. Theory and Methods The effect of crushing gradients for all coherence pathways was modeled according to the associated physics, and a cost function was optimized which maximally crushes all unwanted coherence pathways, while unaffecting the desired coherence pathway(s). The efficacy of the method was tested versus literature schemes from 2 separate MR spectroscopy (MRS) sequences: sLASER and MEGA‐sLASER with both phantom and in vivo experiments. Results Improved crushing power for 2 separate MRS sequences was demonstrated for 2 crushing schemes adopted from the literature in both phantom and in vivo data. Conclusion A novel algorithm and associated software was developed based on rigorous treatment of all coherence pathways, which can be applied to any arbitrary magnetic resonance spectroscopic pulse sequence of interest and any arbitrary coupled spin system. This developed method solves a long‐standing problem in in vivo MRS and is expected to critically improve the data quality of virtually all MRS applications.

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Section: Introductionmentioning

confidence: 99%

Dephasing optimization through coherence order pathway selection (DOTCOPS) for improved crusher schemes in MR spectroscopy

Landheer

Juchem

2018

Magnetic Resonance in Med

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“…In principle, DW‐JPRESS could be combined with parallel imaging to measure the change in ADCs in two or more voxels simultaneously , which would be critical in reducing experiment times for future DW‐MRS applications such as those that compare results between healthy and diseased tissues. However, care must be taken to avoid the possibility of introducing artifacts from a multivoxel reconstruction.…”

Section: Discussionmentioning

confidence: 99%

Diffusion‐weighted J‐resolved spectroscopy

Landheer

Schulte²,

Geraghty

et al. 2016

Magnetic Resonance in Med

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“…Furthermore, the technique is not constrained to single‐voxel applications. It could be incorporated into a typical MRSI technique, or a multivoxel technique that avoids or minimizes k ‐space encoding, such as Hadamard encoding or constrained source space MRS . This could be advantageous for the measurement of the T 1 value of metabolites in pathologies with large heterogeneous regions, or to expedite control measurements from regions of healthy tissue.…”

Section: Discussionmentioning

confidence: 99%

A rapid inversion technique for the measurement of longitudinal relaxation times of brain metabolites: application to lactate in high‐grade gliomas at 3 T

et al. 2016

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The aim of this study was to develop a time-efficient inversion technique to measure the T1 relaxation time of the methyl group of lactate (Lac) in the presence of contaminating lipids and to measure T1 at 3 T in a cohort of primary high-grade gliomas. Three numerically optimized inversion times (TIs) were chosen to minimize the expected error in T1 estimates for a given input total scan duration (set to be 30 min). A two-cycle spectral editing scheme was used to suppress contaminating lipids. The T1 values were then estimated from least-squares fitting of signal measurements versus TI. Lac T1 was estimated as 2000 ± 280 ms. After correcting for T1 (and T2 from literature values), the mean absolute Lac concentration was estimated as 4.3 ± 2.6 mm. The technique developed agrees with the results obtained by standard inversion recovery and can be used to provide rapid T1 estimates of other spectral components as required. Lac T1 exhibits similar variations to other major metabolites observable by MRS in high-grade gliomas. The T1 estimate provided here will be useful for future MRS studies wishing to report relaxation-corrected estimates of Lac concentration as an objective tumor biomarker. Copyright © 2016 John Wiley & Sons, Ltd.

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Constrained Source Space MR Spectroscopy: Multiple Voxels, No Gradient Readout

Abstract: BACKGROUND AND PURPOSE: Our goal was to develop a novel technique for measuring a small number of localized spectra simultaneously and in a time-efficient manner.

Cited by 5 publications

References 26 publications

Dephasing optimization through coherence order pathway selection (DOTCOPS) for improved crusher schemes in MR spectroscopy

Dephasing optimization through coherence order pathway selection (DOTCOPS) for improved crusher schemes in MR spectroscopy

Diffusion‐weighted J‐resolved spectroscopy

A rapid inversion technique for the measurement of longitudinal relaxation times of brain metabolites: application to lactate in high‐grade gliomas at 3 T

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