A Potential Magnetic Resonance Imaging Technique Based on Chemical Exchange Saturation Transfer for In Vivo γ-Aminobutyric Acid Imaging

Yan, Gen; Zhang, Tao; Dai, Zhuozhi; Yi, Meizhi; Jia, Yanlong; Nie, Tingting; Zhang, Handi; Xiao, Gang; Wu, Renhua

doi:10.1371/journal.pone.0163765

Cited by 23 publications

(19 citation statements)

References 29 publications

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“…Because of the substantial difference in amide, amine, and hydroxyl CEST exchange properties, it will be interesting to further explore QUASS CEST analysis in the future. [53][54][55][56][57][58]…”

Section: Discussionmentioning

confidence: 99%

Quasi‐steady state chemical exchange saturation transfer (QUASS CEST) analysis—correction of the finite relaxation delay and saturation time for robust CEST measurement

Sun

2021

Magnetic Resonance in Med

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CEST provides a MR contrast mechanism sensitizing to the exchange between dilute labile and bulk water protons. However, the CEST effect depends on the RF saturation duration and relaxation delay, which need to be long to reach its steady state. Our study aims to estimate the QUAsi-Steady State (QUASS) CEST signal from experiments with shorter saturation and relaxation delay times. Methods: The evolution of the CEST signal was modeled as a function of the bulk water longitudinal relaxation rate during the relaxation delay (Td) and spin-lock relaxation rate during the RF saturation (Ts), from which the QUASS CEST effect is solved. Numeric simulations were programmed to compare the apparent CEST and QUASS CEST effects as a function of Ts and Td times. We also performed CEST MRI experiments from a creatine-gel pH phantom under serially varied Ts and Td times. Results: The numeric simulation showed that although the apparent CEST effect depends on Td and Ts, the QUASS CEST solution has little dependence. Phantom results showed that the routine CEST pH contrast could be described by a nonlinear regression model (ie, ΔCESTR = ΔCESTR app eq 1 − e − R app 1 ⋅ t). We had ΔCESTR app eq = 3.90 ± 0.03% (P < 5e−8) and R app 1 = 0.62 ± 0.02 s − 1 (P < 5e−6). For the QUASS CEST analysis, we modeled the pH contrast as ΔCESTR = ΔCESTR QUASS eq + s ⋅ t, using a linear regression model. We had ΔCESTR QUASS eq = 3.63 ± 0.01% (P < 5e−9) and s = −0.02 ± 0.00% ∕s (P < 0.01), the slope of which is minimal. Conclusions: The QUASS CEST algorithm provides a post-processing solution that facilitates robust CEST measurement. K E Y W O R D S chemical exchange saturation transfer, CEST, QUAsi-Steady State CEST, QUASS CEST 1 | INTRODUCTION Chemical exchange saturation transfer (CEST) contrast mechanism is sensitive to the exchange process between dilute labile groups and bulk water protons. 1 It has been increasingly adopted for examining disorders such as acute stroke, 2-7 tumors, 8-11 and epilepsy. 12,13 For example, pH-sensitive endogenous amide proton transfer (APT) MRI refines the routine

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Section: Discussionmentioning

confidence: 99%

Quasi‐steady state chemical exchange saturation transfer (QUASS CEST) analysis—correction of the finite relaxation delay and saturation time for robust CEST measurement

Sun

2021

Magnetic Resonance in Med

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“…GABA-CEST MRI was performed as reported in our previous study [75]. Briefly, GABA-CEST MRI was acquired on a 7.0 T small-animal MRI scanner (Agilent Technologies, USA), using a TimeMedical surface coil (TimeMedical Technologies, China).…”

Section: Methodsmentioning

confidence: 99%

Ginsenoside Rb1 regulates prefrontal cortical GABAergic transmission in MPTP-treated mice

Liu

Zong

Huang

et al. 2019

Aging

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Parkinson’s disease (PD) is a common neurodegenerative disease, featured by motor deficits and non-motor symptoms such as cognitive impairment, and malfunction of gamma-aminobutyric acid (GABA) mediated inhibitory transmission plays an important role in PD pathogenesis. The ginsenoside Rb1 molecule, a major constituent of the extract from the Ginseng root, has been demonstrated to ameliorate motor deficits and prevent dopaminergic neuron death in PD. However, whether Rb1 can regulate GABAergic transmission in PD-associated deficits and its underlying mechanisms are still unclear. In this study, we explored the effects of Rb1 on the GABAergic synaptic transmission in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. We demonstrated that Rb1 can bind with GABA A Rα1 and increase its expression in the SH-SY5Y cells and in the prefrontal cortex (PFC) of MPTP model in vitro and in vivo . Furthermore, Rb1 can promote prefrontal cortical GABA level and GABAergic transmission in MPTP-treated mice. We also revealed that Rb1 may suppress presynaptic GABA B R1 to enhance GABA release and GABA A receptor-mediated inhibitory transmission. In addition, Rb1 attenuated MPTP-induced dysfunctional gait dynamic and cognitive impairment, and this neuroprotective mechanism possibly involved regulating prefrontal cortical GABAergic transmission. Thus, Rb1 may serve as a potential drug candidate for the treatment of PD.

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“…Existing in-vivo approaches for measuring GABA include positron emission tomography (PET) [8], single photon emission tomography (SPECT) [9], proton magnetic resonance spectroscopy ( 1 H MRS) [10] and chemical exchange saturation transfer (CEST) [11, 12]. Among these, MRS at ultrahigh filed (UHF ≥ 7 T) is widely used due to high sensitivity and specificity for measuring GABA [13].…”

Section: Introductionmentioning

confidence: 99%

A comparison of sLASER and MEGA-sLASER using simultaneous interleaved acquisition for measuring GABA in the human brain at 7T

et al. 2019

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γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter, is challenging to measure using proton spectroscopy due to its relatively low concentration, J-coupling and overlapping signals from other metabolites. Currently, the prevalent methods for detecting GABA at ultrahigh field strengths (≥ 7 T) are GABA-editing and model fitting of non-editing single voxel spectra. These two acquisition approaches have their own advantages: the GABA editing approach directly measures the GABA resonance at 3 ppm, whereas the fitting approach on the non-editing spectrum allows the detection of multiple metabolites, and has an SNR advantage over longer echo time (TE) acquisitions. This study aims to compare these approaches for estimating GABA at 7 T. We use an interleaved sequence of semi-LASER (sLASER: TE = 38 ms) and MEGA-sLASER (TE = 80 ms). This simultaneous interleaved acquisition minimizes the differential effect of extraneous factors, and enables an accurate comparison of the two acquisition methods. Spectra were acquired with an 8 ml isotropic voxel at six different brain regions: anterior-cingulate cortex, dorsolateral-prefrontal cortex, motor cortex, occipital cortex, posterior cingulate cortex, and precuneus. Spectral fitting with LCModel quantified the GABA to total Cr (tCr: Creatine + Phosphocreatine) concentration ratio. After correcting the T2 relaxation time variation, GABA/tCr ratios were similar between the two acquisition approaches. GABA editing showed smaller spectral fitting error according to Cramér–Rao lower bound than the sLASER approach for all regions examined. We conclude that both acquisition methods show similar accuracy but the precision of the MEGA-editing approach is higher for GABA measurement. In addition, the 2.28 ppm GABA resonance was found to be important for estimating GABA concentration without macromolecule contamination in the GABA-edited acquisition, when utilizing spectral fitting with LCModel.

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A Potential Magnetic Resonance Imaging Technique Based on Chemical Exchange Saturation Transfer for In Vivo γ-Aminobutyric Acid Imaging

Cited by 23 publications

References 29 publications

Quasi‐steady state chemical exchange saturation transfer (QUASS CEST) analysis—correction of the finite relaxation delay and saturation time for robust CEST measurement

Quasi‐steady state chemical exchange saturation transfer (QUASS CEST) analysis—correction of the finite relaxation delay and saturation time for robust CEST measurement

Ginsenoside Rb1 regulates prefrontal cortical GABAergic transmission in MPTP-treated mice

A comparison of sLASER and MEGA-sLASER using simultaneous interleaved acquisition for measuring GABA in the human brain at 7T

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