In vivo three‐dimensional whole‐brain pulsed steady‐state chemical exchange saturation transfer at 7 T

Jones, Craig K.; Polders, Daniel; Hua, Jun; Zhu, He; Hoogduin, Hans; Zhou, Jinyuan; Luijten, Peter R.; Zijl, Peter C.M. van

doi:10.1002/mrm.23141

Cited by 184 publications

(324 citation statements)

References 46 publications

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“…Next, B 1 amplitude was fixed to 1 μT while pulse duration was varied from 0 ms – 60 ms. A 3D pulsed-CEST approach (16) was chosen using a single RF irradiation every T R , creating a cumulative saturation effect and building up steady state over multiple short T R ’s. Physical constants included: 1) water protons: T 1 = 2.3 s and T 2 = 45 ms, 2) amide protons: T 1 = 1.0 s, T 2 = 20 ms, and k ex = 50 s −1 , 3) hydroxyl protons: T 1 = 1.0 s, T 2 = 40 ms, and k ex = 500 s −1 , and 4) MT: T 1 = 1.6 s, T 2 = 0.001 ms, and k ex = 20 s −1 (5, 17).…”

Section: Methodsmentioning

confidence: 99%

Optimization of 7-T Chemical Exchange Saturation Transfer Parameters for Validation of Glycosaminoglycan and Amide Proton Transfer of Fibroglandular Breast Tissue

Dula¹,

Arlinghaus²,

Williams³

et al. 2015

Radiology

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Purpose The two purposes of this study were to: 1) implement simulation-optimized chemical exchange saturation transfer (CEST) measurements sensitive to amide proton transfer (APT) and glycosaminoglycans (GAG) hydroxyl proton transfer effects in the human breast at 7 Tesla, and 2) determine the reliability of these techniques for evaluation of fibroglandular tissue in the healthy breast as a benchmark for future studies of pathology. Materials and Methods All human studies were IRB approved, HIPPA compliant, and included informed consent. The CEST parameters of saturation duration (25 ms) and amplitude (1 μT) were chosen based on simulation-driven optimization for APT contrast with the CEST effect quantified using residuals of a Lorentzian fit. Optimized parameters were implemented at 7 Tesla in ten healthy women in two separate scans to evaluate the reliability of CEST MRI measurements in the breast. CEST z-spectra were acquired over saturation offset frequencies ranging between ±40 ppm using a quadrature unilateral breast coil. The scan-rescan reliability was assessed in terms of the intraclass correlation coefficient, which indicates the ratio of between-subject variation to total variation. Results Simulations of the Bloch Equations with chemical exchange guided selection of optimal values for pulse duration and amplitude, 25 ms and 1 μT, respectively. Reliability was evaluated using intraclass correlation coefficients (95% confidence intervals) with acceptable results: 0.963 (0.852, 0.991) and 0.903 (0.609, 0.976) for APT and GAG, respectively. Conclusion We used simulations to derive optimal CEST preparation parameters to elicit maximal CEST contrast in healthy fibroglandular breast tissue due to APT at 7 T. We demonstrate that by using these parameters, obtaining reproducible values for both the amide and hydroxyl protons from of CEST MRI at 7 T is feasible in the human breast

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Section: Methodsmentioning

confidence: 99%

Optimization of 7-T Chemical Exchange Saturation Transfer Parameters for Validation of Glycosaminoglycan and Amide Proton Transfer of Fibroglandular Breast Tissue

Dula¹,

Arlinghaus²,

Williams³

et al. 2015

Radiology

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“…This method was demonstrated by Liu et al 119 for some paraCEST agents in phantoms and by Jones et al 71,72 in vivo in the human brain (Figure 7b and d). In Figure 13, the upfield LD spectrum of the right posterior lobe in human brain is compared with 1 H MRS data from the same region.…”

Section: Analysis Of Cest Spectra Without Asymmetry Analysismentioning

confidence: 84%

“…rNOE effects on mobile molecules have further been detected in the brain in animals 70 and humans. 71 However, they are difficult to detect without interference with the MTC effect, which is of course also NOE based. Only at very low B 1 field does the fine structure of the mobile components become visible above a broader MTC residual.…”

Section: Relayed Nuclear Overhauser Enhancement (Rnoe)mentioning

confidence: 99%

“…While agreement is evident for a number of resonances, it was later concluded that a broader component from residual MTC was still present in the LD data, causing enhancement of WM in LD-based images. 71,72 Around the same time, Zaiss et al 120 theoretically demonstrated the possibility of estimating and removing DS and MTC contributions with Lorentzian fitting when the weak-saturation pulse condition is applicable. In a related approach, CEST effects have also been filtered from other MTC and DS effects by using time-domain analysis in an approach known as time-domain removal of irrelevant magnetization (TRIM).…”

Section: Analysis Of Cest Spectra Without Asymmetry Analysismentioning

confidence: 99%

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Proton Chemical Exchange Saturation Transfer (CEST) MRS and MRI

Zijl

Sehgal

2016

eMagRes

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Proton magnetic resonance spectroscopy ( 1 H MRS) of biological systems has higher specificity than MRI because resonances of multiple metabolites can be distinguished, reflecting chemistry and physiology in situ. Unfortunately, this approach has very low sensitivity as the metabolites are typically at millimolar concentrations compared to the molar signal strength of water-based MRI. As a consequence, even though 1 H MRS is a powerful and common research tool, its inroad into daily clinical practice has been limited. Until very recently, 1 H MRS applications have focused on the resonances upfield (i.e., at lower frequency) of the water resonance. This article deals with protons that are generally not observed in a typical water-suppressed spectrum, namely, the exchangeable protons found predominantly downfield from water. These can usually be detected by MRS only if the transfer of water proton saturation (established during water suppression) is not a confounding factor, or by using water exchange (WEX) spectroscopy, in which RF labeling of the water protons is transferred to the exchangeable protons and subsequently detected. More importantly, it has recently become clear that the presence of such exchangeable protons on low concentration solute molecules can be detected via the water signal by RF labeling of these protons and subsequent transfer of this label to water protons. This process, leading to saturation of the water signal and enhancement of the effect through repeated exchange, can be used for the imaging of metabolite signals or exchangeable-proton-based contrast agents with enhanced sensitivity. This has given rise to the field of chemical exchange saturation transfer (CEST) MRI, which has greatly increased the potential for translating spectroscopic methods to the clinic. Examples include the measurement of pH, temperature, and enzyme activity as well as detection of cellular metabolites, ions, and proteins and peptides. In addition, bio-organic compounds can now be used for contrast agents, cell and nanoparticle labeling, and reporter genes.

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“…Recently, steady-state methods for fast CEST imaging were reported, where the long saturation irradiation was split into short parts with intermittent acquisition [15, 16]. In steady-state methods, the data acquired first (with shorter saturation time) fills the outer portion of the k-space and the data acquired later (with longer saturation time) fills the center of the k-space.…”

Section: Introductionmentioning

confidence: 99%

Balanced Steady-State Free Precession (bSSFP) from an effective field perspective: Application to the detection of chemical exchange (bSSFPX)

Shu

Liu

Grant

et al. 2017

Journal of Magnetic Resonance

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Chemical exchange saturation transfer (CEST) is a novel contrast mechanism and it is gaining increasing popularity as many promising applications have been proposed and investigated. Fast and quantitative CEST imaging techniques are further needed in order to increase the applicability of CEST for clinical use as well as to derive quantitative physiological and biological information. Steady-state methods for fast CEST imaging have been reported recently. Here, we observe that an extreme case of these methods is a balanced steady-state free precession (bSSFP) sequence. The bSSFP in itself is sensitive to the exchange processes; hence, no additional saturation or preparation is needed for CEST-like data acquisition. The bSSFP experiment can be regarded as observation during saturation, without separate saturation and acquisition modules as used in standard CEST and similar experiments. One of the differences from standard CEST methods is that the bSSFP spectrum is an XY-spectrum not a Z-spectrum. As the first proof-of-principle step, we have implemented the steady state bSSFP sequence for chemical exchange detection (bSSFPX) and verified its feasibility in phantom studies. These studies have shown that bSSFPX can achieve exchange-mediated contrast comparable to the standard CEST experiment. Therefore, the bSSFPX method has a potential for fast and quantitative CEST data acquisition.

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In vivo three‐dimensional whole‐brain pulsed steady‐state chemical exchange saturation transfer at 7 T

Cited by 184 publications

References 46 publications

Optimization of 7-T Chemical Exchange Saturation Transfer Parameters for Validation of Glycosaminoglycan and Amide Proton Transfer of Fibroglandular Breast Tissue

Optimization of 7-T Chemical Exchange Saturation Transfer Parameters for Validation of Glycosaminoglycan and Amide Proton Transfer of Fibroglandular Breast Tissue

Proton Chemical Exchange Saturation Transfer (CEST) MRS and MRI

Balanced Steady-State Free Precession (bSSFP) from an effective field perspective: Application to the detection of chemical exchange (bSSFPX)

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