Progress toward quantitative in vivo chemical exchange saturation transfer (CEST) MRI

Ji, Yang; Zhou, Iris Yuwen; Qiu, Bensheng; Sun, Phillip Zhe

doi:10.1002/ijch.201700025

Cited by 16 publications

(22 citation statements)

References 193 publications

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“…[28][29][30][31] Ideally, for providing the most useful estimation of the metabolite of interest, the actual physical CEST propertiesproton exchange rate, and solute concentration should be mapped. In accordance, various efforts were previously taken to achieve quantitative CEST imaging 32 such as the quantitation of exchange using saturation power (QUESP) or time (QUEST) [33][34][35] and Omega plot 36 methods. These methods exploit the dependency of the CEST signal on the saturation power (or saturation time) and fit the MTR asym for a single offset as a function of the saturation parameter to estimate the labile proton volume fraction and exchange rate.…”

Section: Introductionmentioning

confidence: 99%

CEST MR‐Fingerprinting: Practical considerations and insights for acquisition schedule design and improved reconstruction

Perlman

Herz

Zaiß

et al. 2019

Magnetic Resonance in Med

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Purpose: To understand the influence of various acquisition parameters on the ability of CEST MR-Fingerprinting (MRF) to discriminate different chemical exchange parameters and to provide tools for optimal acquisition schedule design and parameter map reconstruction. Methods: Numerical simulations were conducted using a parallel computing implementation of the Bloch-McConnell equations, examining the effect of TR, TE, flip-angle, water T 1 and T 2 , saturation-pulse duration, power, and frequency on the discrimination ability of CEST-MRF. A modified Euclidean distance matching metric was evaluated and compared to traditional dot product matching. L-Arginine phantoms of various concentrations and pH were scanned at 4.7T and the results compared to numerical findings. Results: Simulations for dot product matching demonstrated that the optimal flipangle and saturation times are 30 • and 1100 ms, respectively. The optimal maximal saturation power was 3.4 μT for concentrated solutes with a slow exchange rate, and 5.2 μT for dilute solutes with medium-to-fast exchange rates. Using the Euclidean distance matching metric, much lower maximum saturation powers were required (1.6 and 2.4 μT, respectively), with a slightly longer saturation time (1500 ms) and 90 • flip-angle. For both matching metrics, the discrimination ability increased with the repetition time. The experimental results were in agreement with simulations, demonstrating that more than a 50% reduction in scan-time can be achieved by Euclidean distance-based matching. Conclusions: Optimization of the CEST-MRF acquisition schedule is critical for obtaining the best exchange parameter accuracy. The use of Euclidean distance-based matching of signal trajectories simultaneously improved the discrimination ability and reduced the scan time and maximal saturation power required. |

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Section: Introductionmentioning

confidence: 99%

CEST MR‐Fingerprinting: Practical considerations and insights for acquisition schedule design and improved reconstruction

Perlman

Herz

Zaiß

et al. 2019

Magnetic Resonance in Med

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“…For example, the combination of the concentration of various metabolites and their chemical exchange rates can be used to assess different tissue environments such as cancer vs. contralateral region, or ischaemic vs. non-ischaemic tissues (58). Measurements of chemical exchange rates can be also used to select the most appropriate parameters for CEST acquisition (59), (60). This is important because CEST contrast is complex.…”

Section: Techniques To Measure the Exchange Ratesmentioning

confidence: 99%

Pulse sequences for measuring exchange rates between proton species: From unlocalised NMR spectroscopy to chemical exchange saturation transfer imaging

Demetriou

Kujawa

Golay

2020

Progress in Nuclear Magnetic Resonance Spectroscopy

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“…When there exists the B 0 inhomogeneity, the spillover effect is no longer symmetric. Furthermore, the B 1 inhomogeneity of the RF pulse may also cause spatial variation in labeling efficiency and spillover factor [35]. Apart from the efforts in improving magnetic field inhomogeneities using hardware-based methods, such as parallel transmit technologies [36], post-processing algorithms have been developed for field inhomogeneity correction [37,38].…”

Section: Correction Of B 0 and Bmentioning

confidence: 99%

“…The comprehensive methods like simultaneous mapping of B 0 and B 1 fields [35,41], and model-based correction algorithm, [42] have also been developed to improve the accuracy of MTR asym or PTR.…”

Section: Correction Of B 0 and Bmentioning

confidence: 99%

Basics of Chemical Exchange Saturation Transfer (CEST) Magnetic Resonance Imaging

Murase¹

2018

High-Resolution Neuroimaging - Basic Physical Principles and Clinical Applications

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Chemical exchange saturation transfer (CEST) is one of the contrast mechanisms in magnetic resonance imaging (MRI) and has been used to detect dilute proteins through the interaction between bulk water and labile solute protons. Amide proton transfer (APT) MRI has been developed for imaging diseases such as acute stroke. Moreover, various CEST agents have been explored to enhance the CEST effect. The contrast mechanism of CEST or APT MRI, however, is complex and depends not only on the concentration of amide protons or CEST agents and exchange properties, but also varies with imaging parameters such as radiofrequency (RF) power and magnetic field strength. When there are multiple exchangeable pools within a single CEST system, the contrast mechanism of CEST becomes even more complex. Numerical simulations are useful and effective for analyzing the complex contrast mechanism of CEST and for investigating the optimal imaging parameter values. In this chapter, we present the basics of CEST or APT MRI and a simple and fast numerical method for solving the time-dependent Bloch-McConnell equations for analyzing the behavior of magnetization and/or contrast mechanism in CEST or APT MRI. We also present a method for analyzing the behavior of magnetization in spin-locking CEST MRI.

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Progress toward quantitative in vivo chemical exchange saturation transfer (CEST) MRI

Cited by 16 publications

References 193 publications

CEST MR‐Fingerprinting: Practical considerations and insights for acquisition schedule design and improved reconstruction

CEST MR‐Fingerprinting: Practical considerations and insights for acquisition schedule design and improved reconstruction

Pulse sequences for measuring exchange rates between proton species: From unlocalised NMR spectroscopy to chemical exchange saturation transfer imaging

Basics of Chemical Exchange Saturation Transfer (CEST) Magnetic Resonance Imaging

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