Acquisition sequences and reconstruction methods for fast chemical exchange saturation transfer imaging

Zhang, Yi; Zu, Tao; Liu, Ruibin; Zhou, Jinyuan

doi:10.1002/nbm.4699

Cited by 22 publications

(32 citation statements)

References 135 publications

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“…[50][51][52] The side-chain amide signals between 2.5 to 3.0 ppm are expected to be much smaller than the Arg proton signal as previously recorded by the downfield MRS study 54 and CEST study at an extremely high MRI field (21.1 T). 41 In the current study, contributions from Asn and Gln side-chain amide protons were summarized by a single peak at 2.28 ppm with GuanCEST because of a low spectral resolution at 3 T. However, an additional peak should be added for the side-chain amide protons for the HSR-CEST at high MRI fields.…”

Section: Discussionmentioning

confidence: 96%

“…A cw saturation scheme provides a high labeling efficiency 41 . When performing CEST with multi‐slice turbo spin‐echo (TSE) acquisition, the MTC from the neighboring slices can also interference with the CEST signal 42 .…”

Section: Methodsmentioning

confidence: 99%

“…A cw saturation scheme provides a high labeling efficiency. 41 When performing CEST with multi-slice turbo spin-echo (TSE) acquisition, the MTC from the neighboring slices can also interference with the CEST signal. 42 Therefore, a single slice cw TSE (cwTSE) sequence (Figure 1A) was used to optimize the B 1 value and serve as a reference for determining the labeling efficiency of other CEST sequences.…”

Section: Mri Experimentsmentioning

confidence: 99%

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Guanidinium and amide CEST mapping of human brain by high spectral resolution CEST at 3 T

Wang

Park

Kamson

et al. 2022

Magnetic Resonance in Med

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Purpose: To extract guanidinium (Guan) and amide CEST on the human brain at 3 T MRI with the high spectral resolution (HSR) CEST combined with the polynomial Lorentzian line-shape fitting (PLOF).Methods: Continuous wave (cw) turbo spin-echo (TSE) CEST was implemented to obtain the optimum saturation parameters. Both Guan and amide CEST peaks were extracted and quantified using the PLOF method. The NMR spectra on the egg white phantoms were acquired to reveal the fitting range and the contributions to the amide and GuanCEST. Two types of CEST approaches, including cw gradient-and spin-echo (cwGRASE) and steady state EPI (ssEPI), were implemented to acquire multi-slice HSR-CEST. Results: GuanCEST can be extracted with the PLOF method at 3 T, and the optimum B 1 = 0.6 μT was determined for GuanCEST in white matter (WM) and 1.0 μT in gray matter (GM). The optimum B 1 = 0.8-1 μT was found for amide-CEST. AmideCEST is lower in both WM and GM collected with ssEPI compared to those by cwGRASE (ssEPI = [1.27-1.63]%; cwGRASE = [2.19-2.25]%). The coefficients of variation (COV) of the amide and Guan CEST in both WM and GM for ssEPI (COV: 28.6-33.4%) are significantly higher than those of cwGRASE (COV: 8.6-18.8%). Completely different WM/GM contrasts for Guan and amide CEST were observed between ssEPI and cwGRASE. The amideCEST was found to have originated from the unstructured amide protons as suggested by the NMR spectrum of the unfolded proteins in egg white. Conclusion:Guan and amide CEST mapping can be achieved by the HSR-CEST at 3 T combing with the PLOF method. K E Y W O R D Schemical exchange saturation transfer (CEST), magnetization transfer contrast (MTC), guanidinium CEST, amide CEST, continuous wave gradient-and spin-echo (cwGRASE), steady state EPI (ssEPI), polynomial Lorentzian line-shape fitting (PLOF)

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Section: Discussionmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Mri Experimentsmentioning

confidence: 99%

See 1 more Smart Citation

Guanidinium and amide CEST mapping of human brain by high spectral resolution CEST at 3 T

Wang

Park

Kamson

et al. 2022

Magnetic Resonance in Med

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“…In addition, qCEST analysis requires an RF saturation time (10 s in our study) to reach a steady-state and at least three different CEST experiments with different B 1 amplitudes to perform the Ω-plots. By using dual-gradient echo strategies [41], simulated multi-slice gradient echo (GRE) sequences [42], phase-shifted multiplanar CEST-fast imaging with steady-state free precession (FISP) sequences [43], ultrafast one-shot acquisition [44], compressed sensing [45], and other imaging techniques, this limitation could be addressed in future studies [46]. Second, the two IVD MR studies we performed (in situ and in vivo) have only limited comparability.…”

Section: Discussionmentioning

confidence: 99%

Lorentzian-Corrected Apparent Exchange-Dependent Relaxation (LAREX) Ω-Plot Analysis—An Adaptation for qCEST in a Multi-Pool System: Comprehensive In Silico, In Situ, and In Vivo Studies

Radke

Wilms

Frenken

et al. 2022

IJMS

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Based on in silico, in situ, and in vivo studies, this study aims to develop a new method for the quantitative chemical exchange saturation transfer (qCEST) technique considering multi-pool systems. To this end, we extended the state-of-the-art apparent exchange-dependent relaxation (AREX) method with a Lorentzian correction (LAREX). We then validated this new method with in situ and in vivo experiments on human intervertebral discs (IVDs) using the Kendall-Tau correlation coefficient. In the in silico experiments, we observed significant deviations of the AREX method as a function of the underlying exchange rate (kba) and fractional concentration (fb) compared to the ground truth due to the influence of other exchange pools. In comparison to AREX, the LAREX-based Ω-plot approach yielded a substantial improvement. In the subsequent in situ and in vivo experiments on human IVDs, no correlation to the histological reference standard or Pfirrmann classification could be found for the fb (in situ: τ = −0.17 p = 0.51; in vivo: τ = 0.13 p = 0.30) and kba (in situ: τ = 0.042 p = 0.87; in vivo: τ = −0.26 p = 0.04) of Glycosaminoglycan (GAG) with AREX. In contrast, the influence of interfering pools could be corrected by LAREX, and a moderate to strong correlation was observed for the fractional concentration of GAG for both in situ (τ = −0.71 p = 0.005) and in vivo (τ = −0.49 p < 0.001) experiments. The study presented here is the first to introduce a new qCEST method that enables qCEST imaging in systems with multiple proton pools.

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“…Over the years, a variety of reconstruction‐related methods for accelerating CEST acquisition have been developed 20 . Based on the compressibility or sparsity of the image in the transform domain, compressed sensing 21 has been applied to accelerate CEST imaging 22–24 .…”

Section: Introductionmentioning

confidence: 99%

Joint K‐space and Image‐space Parallel Imaging (KIPI) for accelerated chemical exchange saturation transfer acquisition

Sun

et al. 2022

Magnetic Resonance in Med

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Purpose To develop an auto‐calibrated technique by joint K‐space and Image‐space Parallel Imaging (KIPI) for accelerated CEST acquisition. Theory and Methods The KIPI method selects a calibration frame with a low acceleration factor (AF) and auto‐calibration signals (ACS) acquired, from which the coil sensitivity profiles and artifact correction maps are calculated after restoring the k‐space by GRAPPA. Then the other frames with high AF and without ACS can be reconstructed by SENSE and artifact suppression. The signal leakage due to the T2‐decay filtering in k‐space compromises the SENSE reconstruction, which can be corrected by the artifact suppression algorithm of KIPI. The 2D and 3D imaging experiments were done on the phantom, healthy volunteer, and brain tumor patient with a 3T scanner. Results The proposed KIPI method was evaluated by retrospectively undersampled data with variable AFs and compared against existing parallel imaging methods (SENSE/auto, GRAPPA, and ESPIRiT). KIPI enabled CEST frames with random AFs to achieve similar image quality, eliminated the strong aliasing artifacts, and generated significantly smaller errors than the other methods (p < 0.01). The KIPI method permitted an AF up to 12‐fold in both phase‐encoding and slice‐encoding directions for 3D CEST source images, achieving an overall 8.2‐fold speedup in scan time. Conclusion KIPI is a novel auto‐calibrated parallel imaging method that enables variable AFs for different CEST frames, achieves a significant reduction in scan time, and does not compromise the accuracy of CEST maps.

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Acquisition sequences and reconstruction methods for fast chemical exchange saturation transfer imaging

Cited by 22 publications

References 135 publications

Guanidinium and amide CEST mapping of human brain by high spectral resolution CEST at 3 T

Guanidinium and amide CEST mapping of human brain by high spectral resolution CEST at 3 T

Lorentzian-Corrected Apparent Exchange-Dependent Relaxation (LAREX) Ω-Plot Analysis—An Adaptation for qCEST in a Multi-Pool System: Comprehensive In Silico, In Situ, and In Vivo Studies

Joint K‐space and Image‐space Parallel Imaging (KIPI) for accelerated chemical exchange saturation transfer acquisition

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