1
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Wang D, Stirnberg R, Stöcker T. Improved gradient echo magnitude- and phase-based mapping of T 2 $$ {\mathrm{T}}_2 $$ using multiple RF spoiling increments at 3T and 7T. Magn Reson Med 2024. [PMID: 38987985 DOI: 10.1002/mrm.30217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 05/23/2024] [Accepted: 06/25/2024] [Indexed: 07/12/2024]
Abstract
PURPOSE The transverse relaxation time T 2 $$ {}_2 $$ holds significant relevance in clinical applications and research studies. Conventional T 2 $$ {}_2 $$ mapping approaches rely on spin-echo sequences, which require lengthy acquisition times and involve high radiofrequency (RF) power deposition. An alternative gradient echo (GRE) phase-based T 2 $$ {}_2 $$ mapping method, utilizing steady-state acquisitions at one small RF spoil phase increment, was recently demonstrated. Here, a modified magnitude- and phase-based T 2 $$ {}_2 $$ mapping approach is proposed, which improvesT 2 $$ {\mathrm{T}}_2 $$ estimations by simultaneous fitting ofT 1 $$ {\mathrm{T}}_1 $$ and signal amplitude (A ∝ P D $$ A\propto PD $$ ) at three or more RF spoiling phase increments, instead of assuming a fixedT 1 $$ {\mathrm{T}}_1 $$ value. METHODS The feasibility of the magnitude-phase-based method was assessed by simulations, in phantom and in vivo experiments using skipped-CAIPI three-dimensional-echo-planar imaging (3D-EPI) for rapid GRE imaging.T 2 $$ {\mathrm{T}}_2 $$ ,T 1 $$ {\mathrm{T}}_1 $$ and PD estimations obtained by our method were compared toT 2 $$ {\mathrm{T}}_2 $$ of the phase-based method andT 1 $$ {\mathrm{T}}_1 $$ and PD of spoiled GRE-based multi-parameter mapping using a multi-echo version of the same sequence. RESULTS The agreement of the proposedT 2 $$ {\mathrm{T}}_2 $$ with ground truth and referenceT 2 $$ {\mathrm{T}}_2 $$ values was higher than that of phase-basedT 2 $$ {\mathrm{T}}_2 $$ in simulations and in phantom data. While phase-basedT 2 $$ {\mathrm{T}}_2 $$ overestimation increases with actualT 2 $$ {\mathrm{T}}_2 $$ andT 1 $$ {\mathrm{T}}_1 $$ , the proposed method is accurate over a large range of physiologically meaningfulT 2 $$ {\mathrm{T}}_2 $$ andT 1 $$ {\mathrm{T}}_1 $$ values. At the same time, precision is improved. In vivo results were in line with these observations. CONCLUSION Accurate magnitude-phase-based T 2 $$ {}_2 $$ mapping is feasible in less than 5 min scan time for 1 mm nominal isotropic whole-head coverage at 3T and 7T.
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Affiliation(s)
- Difei Wang
- MR Physics, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Rüdiger Stirnberg
- MR Physics, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Tony Stöcker
- MR Physics, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
- Department of Physics & Astronomy, University of Bonn, Bonn, Germany
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2
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Stirnberg R, Deistung A, Reichenbach JR, Breteler MMB, Stöcker T. Rapid submillimeter QSM and R 2* mapping using interleaved multishot 3D-EPI at 7 and 3 Tesla. Magn Reson Med 2024. [PMID: 38988040 DOI: 10.1002/mrm.30216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 06/05/2024] [Accepted: 06/24/2024] [Indexed: 07/12/2024]
Abstract
PURPOSE To explore the high signal-to-noise ratio (SNR) efficiency of interleaved multishot 3D-EPI with standard image reconstruction for fast and robust high-resolution whole-brain quantitative susceptibility (QSM) andR 2 ∗ $$ {R}_2^{\ast } $$ mapping at 7 and 3T. METHODS Single- and multi-TE segmented 3D-EPI is combined with conventional CAIPIRINHA undersampling for up to 72-fold effective gradient echo (GRE) imaging acceleration. Across multiple averages, scan parameters are varied (e.g., dual-polarity frequency-encoding) to additionally correct forB 0 $$ {\mathrm{B}}_0 $$ -induced artifacts, geometric distortions and motion retrospectively. A comparison to established GRE protocols is made. Resolutions range from 1.4 mm isotropic (1 multi-TE average in 36 s) up to 0.4 mm isotropic (2 single-TE averages in approximately 6 min) with whole-head coverage. RESULTS Only 1-4 averages are needed for sufficient SNR with 3D-EPI, depending on resolution and field strength. Fast scanning and small voxels together with retrospective corrections result in substantially reduced image artifacts, which improves susceptibility andR 2 ∗ $$ {R}_2^{\ast } $$ mapping. Additionally, much finer details are obtained in susceptibility-weighted image projections through significantly reduced partial voluming. CONCLUSION Using interleaved multishot 3D-EPI, single-TE and multi-TE data can readily be acquired 10 times faster than with conventional, accelerated GRE imaging. Even 0.4 mm isotropic whole-head QSM within 6 min becomes feasible at 7T. At 3T, motion-robust 0.8 mm isotropic whole-brain QSM andR 2 ∗ $$ {R}_2^{\ast } $$ mapping with no apparent distortion in less than 7 min becomes clinically feasible. Stronger gradient systems may allow for even higher effective acceleration rates through larger EPI factors while maintaining optimal contrast.
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Affiliation(s)
- Rüdiger Stirnberg
- MR Physics, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Andreas Deistung
- Clinic and Outpatient Clinic for Radiology, University Hospital Halle (Saale), University Medicine Halle, Halle (Saale), Germany
| | - Jürgen R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany
| | - Monique M B Breteler
- Population Health Sciences, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
- Faculty of Medicine, Institute for Medical Biometry, Informatics and Epidemiology (IMBIE), University of Bonn, Bonn, Germany
| | - Tony Stöcker
- MR Physics, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
- Department of Physics and Astronomy, University of Bonn, Bonn, Germany
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3
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Hwang SH, Lee HS, Choi SH, Park SH. Distortion correction using topup algorithm by single k-space (TASK) for echo planar imaging. Sci Rep 2023; 13:18751. [PMID: 37907782 PMCID: PMC10618273 DOI: 10.1038/s41598-023-46163-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/28/2023] [Indexed: 11/02/2023] Open
Abstract
Distortion of echo planar imaging (EPI) can be corrected using B0 field maps, which can be estimated with the topup algorithm that requires two EPI images with opposite distortions. In this study, we propose a new algorithm, termed topup algorithm by single K-space (TASK), to generate two input images from a single k-space for the topup algorithm to correct EPI distortions. The centric EPI contains the opposite phase-encoding polarities in one k-space, which can be divided into two halves with opposite distortions. Therefore, two inputs could be extracted by dividing the k-space into halves and processing them using the proposed procedure including an iterative procedure of automatic brain masking and uniformity correction. The efficiency of TASK was evaluated using 3D EPI. Quantitative evaluations showed that TASK corrected EPI distortion at a similar level to the traditional methods. The estimated field maps from the conventional topup and TASK showed a high correlation ([Formula: see text]). An ablation study showed the validity of every suggested step. Furthermore, it was confirmed that TASK was effective for distortion correction of two-shot centric EPI as well, demonstrating its wider applicability. In conclusion, TASK can correct EPI distortions by its own single k-space information with no additional scan.
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Affiliation(s)
- Seon-Ha Hwang
- MRI Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | | | - Seung Hong Choi
- Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea
| | - Sung-Hong Park
- MRI Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Rm 1002, CMS (E16) Building, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea.
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4
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Zhao Z, Zhang X, Zhang X, Cheng Y, Chen L, Shen Z, Chen B, Wang H, Chen Y, Xuan W, Zhuang Z, Zheng X, Geng Y, Dong G, Guan J, Lin Y, Wu R. Amide Proton Transfer-Weighted Imaging Detects Hippocampal Proteostasis Disturbance Induced by Sleep Deprivation at 7.0 T MRI. ACS Chem Neurosci 2022; 13:3597-3607. [PMID: 36469930 PMCID: PMC9785040 DOI: 10.1021/acschemneuro.2c00494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 11/14/2022] [Indexed: 12/09/2022] Open
Abstract
Sleep deprivation leads to hippocampal injury. Proteostasis disturbance is an important mechanism linking sleep deprivation and hippocampal injury. However, identifying noninvasive imaging biomarkers for hippocampal proteostasis disturbance remains challenging. Amide proton transfer-weighted (APTw) imaging is a chemical exchange saturation transfer technique based on the amide protons in proteins and peptides. We aimed to explore the ability of APTw imaging in detecting sleep deprivation-induced hippocampal proteostasis disturbance and its biological significance, as well as its biological basis. In vitro, the feasibility of APTw imaging in detecting changes of the protein state was evaluated, demonstrating that APTw imaging can detect alterations in the protein concentration, conformation, and aggregation state. In vivo, the hippocampal APTw signal declined with increased sleep deprivation time and was significantly lower in sleep-deprived rats than that in normal rats. This signal was positively correlated with the number of surviving neurons counted in Nissl staining and negatively correlated with the expression of glucose-regulated protein 78 evaluated in immunohistochemistry. Differentially expressed proteins in proteostasis network pathways were identified in the hippocampi of normal rats and sleep-deprived rats via mass spectrometry proteomics analysis, providing the biological basis for the change of the hippocampal APTw signal in sleep-deprived rats. These findings demonstrate that APTw imaging can detect hippocampal proteostasis disturbance induced by sleep deprivation and reflect the extent of neuronal injury and endoplasmic reticulum stress.
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Affiliation(s)
- Zhihong Zhao
- Department of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Xiaojun Zhang
- Center
for Core Facilities, Shantou University
Medical College, Shantou515000, China
| | - Xiaolei Zhang
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Yan Cheng
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Lihua Chen
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Zhiwei Shen
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Beibei Chen
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Hongzhi Wang
- Department
of Pathology, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Yue Chen
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Wentao Xuan
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Zerui Zhuang
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Xinhui Zheng
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Yiqun Geng
- Laboratory
of Molecular Pathology, Guangdong Provincial Key Laboratory of Infectious
Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou515000, China
| | - Geng Dong
- Department
of Biochemistry and Molecular Biology, Medical Informatics Research
Center, Shantou University Medical College, Shantou515000, China
| | - Jitian Guan
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Yan Lin
- Department
of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
| | - Renhua Wu
- Department of Medical Imaging, Second Affiliated Hospital, Shantou University Medical College, Shantou515000, China
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5
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Löwen D, Pracht ED, Stirnberg R, Liebig P, Stöcker T. Interleaved binomial kT-Points for water-selective imaging at 7T. Magn Reson Med 2022; 88:2564-2572. [PMID: 35942989 DOI: 10.1002/mrm.29376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/13/2022] [Accepted: 06/13/2022] [Indexed: 11/07/2022]
Abstract
PURPOSE We present a time-efficient water-selective, parallel transmit RF excitation pulse design for ultra-high field applications. METHODS The proposed pulse design method achieves flip angle homogenization at ultra-high fields by employing spatially nonselective k T $$ {\mathrm{k}}_T $$ -points pulses. In order to introduce water-selection, the concept of binomial pulses is applied. Due to the composite nature of k T $$ {\mathrm{k}}_T $$ -points, the pulse can be split into multiple binomial subpulse blocks shorter than half the precession period of fat, that are played out successively. Additional fat precession turns, that would otherwise impair the spectral response, can thus be avoided. Bloch simulations of the proposed interleaved binomial k T $$ {\mathrm{k}}_T $$ -points pulses were carried out and compared in terms of duration, homogeneity, fat suppression and pulse energy. For validation, in vivo MP-RAGE and 3D-EPI data were acquired. RESULTS Simulation results show that interleaved binomial k T $$ {\mathrm{k}}_T $$ -points pulses achieve shorter total pulse durations, improved flip angle homogeneity and more robust fat suppression compared to available methods. Interleaved binomial k T $$ {\mathrm{k}}_T $$ -points can be customized by changing the number of k T $$ {\mathrm{k}}_T $$ -points, the subpulse duration and the order of the binomial pulse. Using shorter subpulses, the number of k T $$ {\mathrm{k}}_T $$ -points can be increased and hence better homogeneity is achieved, while still maintaining short total pulse durations. Flip angle homogenization and fat suppression of interleaved binomial k T $$ {\mathrm{k}}_T $$ -points pulses is demonstrated in vivo at 7T, confirming Bloch simulation results. CONCLUSION In this work, we present a time efficient and robust parallel transmission technique for nonselective water excitation with simultaneous flip angle homogenization at ultra-high field.
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Affiliation(s)
- Daniel Löwen
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | | | | | | | - Tony Stöcker
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
- Department of Physics and Astronomy, University of Bonn, Bonn, Germany
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6
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Wang D, Ehses P, Stöcker T, Stirnberg R. Reproducibility of rapid multi-parameter mapping at 3T and 7T with highly segmented and accelerated 3D-EPI. Magn Reson Med 2022; 88:2217-2232. [PMID: 35877781 DOI: 10.1002/mrm.29383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 06/16/2022] [Accepted: 06/17/2022] [Indexed: 11/11/2022]
Abstract
PURPOSE Quantitative multi-parameter mapping (MPM) has been shown to provide good longitudinal and cross-sectional reproducibility for clinical research. Unfortunately, acquisition times (TAs) are typically infeasible for routine scanning at high resolutions. METHODS A fast whole-brain MPM protocol based on interleaved multi-shot 3D-EPI with controlled aliasing (SC-EPI) at 3T and 7T is proposed and compared with MPM using a standard spoiled gradient echo (FLASH) sequence. Four parameters (R1 , PD, R 2 * $$ {R}_2^{\ast } $$ , and MTsat) were measured in less than 3 min at 1 mm isotropic resolution. Five subjects went through the same scanning sessions twice at each scanner. The intra-subject coefficient of variation (scan-rescan) (CoV) was estimated for each protocol and scanner to assess the longitudinal reproducibility. RESULTS At 3T, the CoV of SC-EPI ranged between 1.2%-4.8% for PD and R1 , 2.8%-10.6% for R 2 * $$ {R}_2^{\ast } $$ and MTsat, which was comparable with FLASH (0.6%-4.9% for PD and R1 , 2.6%-11.3% for R 2 * $$ {R}_2^{\ast } $$ and MTsat). At 7T, where the SC-EPI TA was reduced to ∼2 min, the CoV of SC-EPI (1.4%-10.6% for PD, R1 , and R 2 * $$ {R}_2^{\ast } $$ ) was 1.2-2.4 times larger than the CoV of FLASH (1.0%-15%) and MTsat showed much higher variability across subjects. The SC-EPI-MPM protocol at 3T showed high reproducibility and yielded stable quantitative maps at a clinically feasible resolution and scan time, whereas at 7T, MT saturation homogeneity needs to be improved. CONCLUSION SC-EPI-based MPM is feasible as an additional MRI modality in clinical or population studies where the parameters offer great potential as biomarkers.
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Affiliation(s)
- Difei Wang
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Philipp Ehses
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Tony Stöcker
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Department of Physics and Astronomy, University of Bonn, Bonn, Germany
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7
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Wang C, Lin G, Shen Z, Wang R. Angiopep-2 as an Exogenous Chemical Exchange Saturation Transfer Contrast Agent in Diagnosis of Alzheimer's Disease. JOURNAL OF HEALTHCARE ENGINEERING 2022; 2022:7480519. [PMID: 35422975 PMCID: PMC9005290 DOI: 10.1155/2022/7480519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/22/2022] [Accepted: 03/11/2022] [Indexed: 02/05/2023]
Abstract
BACKGROUND Chemical exchange saturation transfer (CEST) is a novel imaging modality in clinical practice and scientific research. Angiopep-2 is an artificial peptide that can penetrate blood-brain barrier. The aim of this study was to explore the feasibility of Angiopep-2 serving as an exogenous CEST contrast. METHODS Phantoms of Angiopep-2 with different concentrations were prepared and then scanned using the 7.0T small animal MRI scanner. Different parameters including saturation powers and saturation duration were used to achieve the optimal CEST effect, and the optimal parameters were finally selected based on Z-spectra, asymmetric spectra, and phantom CEST imaging. CEST scanning of dimethyl sulfoxide (DMSO), the substance helping Angiopep-2 to be dissolved in water, was performed to exclude its contribution for the CEST effect. RESULTS A broad dip was observed from 2.5 to 3.5 ppm in the Z-spectra of Angiopep-2 phantoms. The most robust CEST was generated at 3.2 ppm when using formula (M -3.2ppm - M +3.2ppm)/M -3.2ppm. The CEST effect of Angiopep-2 was concentration dependent; the effect increased as the concentration increased. In addition, the CEST effect was more obvious as the saturation power increased and peaked at 5.5 µT, and the CEST effect increased as the saturation duration increased. DMSO showed nearly 0% of the CEST effect at 3.2 ppm. CONCLUSIONS Our results demonstrate that Angiopep-2 can act as an excellent exogenous CEST contrast. As it can penetrate blood-brain barrier and bind amyloid-β protein, amyloid-β targeting CEST, with Angiopep-2 as an exogenous contrast agent, can be potentially used as a novel imaging modality for early diagnosis of Alzheimer's disease. Collectively, Angiopep-2 may play a critical role in early diagnosis of Alzheimer's disease.
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Affiliation(s)
- Chengguang Wang
- Department of Neurosurgery, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, Henan, China
| | - Guisen Lin
- Department of Medical Imaging, 2nd Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515000, China
| | - Zhiwei Shen
- Philips Healthcare, Tianzhe Road 16, Chaoyang, Beijing 100600, China
| | - Runrun Wang
- Department of Neurology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, Henan, China
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8
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Raimondo L, Oliveira ĹAF, Heij J, Priovoulos N, Kundu P, Leoni RF, van der Zwaag W. Advances in resting state fMRI acquisitions for functional connectomics. Neuroimage 2021; 243:118503. [PMID: 34479041 DOI: 10.1016/j.neuroimage.2021.118503] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 08/16/2021] [Accepted: 08/22/2021] [Indexed: 01/21/2023] Open
Abstract
Resting state functional magnetic resonance imaging (rs-fMRI) is based on spontaneous fluctuations in the blood oxygen level dependent (BOLD) signal, which occur simultaneously in different brain regions, without the subject performing an explicit task. The low-frequency oscillations of the rs-fMRI signal demonstrate an intrinsic spatiotemporal organization in the brain (brain networks) that may relate to the underlying neural activity. In this review article, we briefly describe the current acquisition techniques for rs-fMRI data, from the most common approaches for resting state acquisition strategies, to more recent investigations with dedicated hardware and ultra-high fields. Specific sequences that allow very fast acquisitions, or multiple echoes, are discussed next. We then consider how acquisition methods weighted towards specific parts of the BOLD signal, like the Cerebral Blood Flow (CBF) or Volume (CBV), can provide more spatially specific network information. These approaches are being developed alongside the commonly used BOLD-weighted acquisitions. Finally, specific applications of rs-fMRI to challenging regions such as the laminae in the neocortex, and the networks within the large areas of subcortical white matter regions are discussed. We finish the review with recommendations for acquisition strategies for a range of typical applications of resting state fMRI.
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Affiliation(s)
- Luisa Raimondo
- Spinoza Centre for Neuroimaging, Amsterdam, the Netherlands; Experimental and Applied Psychology, VU University, Amsterdam, the Netherlands
| | - Ĺcaro A F Oliveira
- Spinoza Centre for Neuroimaging, Amsterdam, the Netherlands; Experimental and Applied Psychology, VU University, Amsterdam, the Netherlands
| | - Jurjen Heij
- Spinoza Centre for Neuroimaging, Amsterdam, the Netherlands; Experimental and Applied Psychology, VU University, Amsterdam, the Netherlands
| | | | - Prantik Kundu
- Hyperfine Research Inc, Guilford, CT, United States; Icahn School of Medicine at Mt. Sinai, New York, United States
| | - Renata Ferranti Leoni
- InBrain, Department of Physics, FFCLRP, University of São Paulo, Ribeirão Preto, Brazil
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9
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Reducing SAR in 7T brain fMRI by circumventing fat suppression while removing the lipid signal through a parallel acquisition approach. Sci Rep 2021; 11:15371. [PMID: 34321529 PMCID: PMC8319205 DOI: 10.1038/s41598-021-94692-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/09/2021] [Indexed: 12/14/2022] Open
Abstract
Ultra-high-field functional magnetic resonance imaging (fMRI) offers a way to new insights while increasing the spatial and temporal resolution. However, a crucial concern in 7T human MRI is the increase in power deposition, supervised through the specific absorption rate (SAR). The SAR limitation can restrict the brain coverage or the minimal repetition time of fMRI experiments. In the majority of today’s studies fMRI relies on the well-known gradient-echo echo-planar imaging (GRE-EPI) sequence, which offers ultrafast acquisition. Commonly, the GRE-EPI sequence comprises two pulses: fat suppression and excitation. This work provides the means for a significant reduction in the SAR by circumventing the fat-suppression pulse. Without this fat-suppression, however, lipid signal can result in artifacts due to the chemical shift between the lipid and water signals. Our approach exploits a reconstruction similar to the simultaneous-multi-slice method to separate the lipid and water images, thus avoiding undesired lipid artifacts in brain images. The lipid-water separation is based on the known spatial shift of the lipid signal, which can be detected by the multi-channel coils sensitivity profiles. Our study shows robust human imaging, offering greater flexibility to reduce the SAR, shorten the repetition time or increase the volume coverage with substantial benefit for brain functional studies.
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10
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Stirnberg R, Stöcker T. Segmented K-space blipped-controlled aliasing in parallel imaging for high spatiotemporal resolution EPI. Magn Reson Med 2020; 85:1540-1551. [PMID: 32936488 DOI: 10.1002/mrm.28486] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 12/16/2022]
Abstract
PURPOSE A segmented k-space blipped-controlled aliasing in parallel imaging (skipped-CAIPI) sampling strategy for EPI is proposed, which allows for a flexible choice of EPI factor and phase encode bandwidth independent of the controlled aliasing in parallel imaging (CAIPI) sampling pattern. THEORY AND METHODS With previously proposed approaches, exactly two EPI trajectories were possible given a specific CAIPI pattern, either with slice gradient blips (blipped-CAIPI) or following a shot-selective CAIPI approach (higher resolution). Recently, interleaved multi-shot segmentation along shot-selective CAIPI trajectories has been applied for high-resolution anatomical imaging. For more flexibility and a broader range of applications, we propose segmentation along any blipped-CAIPI trajectory. Thus, all EPI factors and phase encode bandwidths available with traditional segmented EPI can be combined with controlled aliasing. RESULTS Temporal SNR maps of moderate-to-high-resolution time series acquisitions at varying undersampling factors demonstrate beneficial sampling alternatives to blipped-CAIPI or shot-selective CAIPI. Rapid high-resolution scans furthermore demonstrate SNR-efficient and motion-robust structural imaging with almost arbitrary EPI factor and minimal noise penalty. CONCLUSION Skipped-CAIPI sampling increases protocol flexibility for high spatiotemporal resolution EPI. In terms of SNR and efficiency, high-resolution functional or structural scans benefit vastly from a free choice of the CAIPI pattern. Even at moderate resolutions, the independence of sampling pattern, TE, and image matrix size is valuable for optimized functional protocol design. Although demonstrated with 3D-EPI, skipped-CAIPI is also applicable with simultaneous multislice EPI.
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Affiliation(s)
| | - Tony Stöcker
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Department of Physics and Astronomy, University of Bonn, Bonn, Germany
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11
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Lee H, Choi SH, Sohn CH, Kim SG, Lee J, Park J. Rapid three-dimensional steady-state chemical exchange saturation transfer magnetic resonance imaging. Magn Reson Med 2020; 85:1209-1221. [PMID: 32851659 DOI: 10.1002/mrm.28487] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 07/11/2020] [Accepted: 07/30/2020] [Indexed: 02/05/2023]
Abstract
PURPOSE To make clinically feasible whole-brain chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) by enhancing imaging efficiency. METHODS A novel, whole-brain three-dimensional (3D) steady-state CEST MRI method was introduced by utilizing a time-efficient, fat-suppressed excitation followed by rapid, segmented 3D echo-planar-imaging with incoherent undersampling in k-ω space. Missing signals and CEST-specific spectral images were then jointly estimated directly from incomplete measurements using model-based reconstruction and robust spectral analysis. In vivo studies were performed at 3T both retrospectively (using a fully sampled reference) and prospectively to validate the effectiveness of the proposed method in patients with brain cancer. RESULTS In retrospective studies, the proposed method exhibits superior accuracies to existing methods in estimating images, z-spectra, and APTw relative to the reference. In prospective patient studies, compared with existing methods, the proposed method is statistically significantly different in contrast-to-noise ratio of the APTw contrast between tumor and normal appearing white matter (NAWM) and amide proton transfer weighted contrast (p < 0.05) while not being significantly different in signal-to-noise ratio in an NAWM region. CONCLUSIONS We successfully demonstrated that it is feasible to perform whole-brain CEST MRI roughly within 4 minutes for patients with brain cancer. It is expected that the proposed method widens clinical utilities of CEST MRI.
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Affiliation(s)
- Hoonjae Lee
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.,Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Republic of Korea
| | - Seung Hong Choi
- Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Chul-Ho Sohn
- Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Seong-Gi Kim
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.,Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Republic of Korea
| | - Joonyeol Lee
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.,Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Republic of Korea
| | - Jaeseok Park
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.,Biomedical Institute for Convergence, Sungkyunkwan University, Suwon, Republic of Korea
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12
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Chen Y, Dai Z, Fan R, Mikulis DJ, Qiu J, Shen Z, Wang R, Lai L, Tang Y, Li Y, Jia Y, Yan G, Wu R. Glymphatic System Visualized by Chemical-Exchange-Saturation-Transfer Magnetic Resonance Imaging. ACS Chem Neurosci 2020; 11:1978-1984. [PMID: 32492333 DOI: 10.1021/acschemneuro.0c00222] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Dysfunction of the glymphatic system may play a significant role in the development of neurodegenerative diseases. However, in vivo imaging of the glymphatic system is challenging. In this study, we describe an unconventional MRI method for imaging the glymphatic system based on chemical exchange saturation transfer, which we tested in an in vivo porcine model of impaired glymphatic function. The blood, lymph, and cerebrospinal fluid (CSF) from one pig were used for testing the MRI effect in vitro at 7 Tesla (T). Unilateral deep cervical lymph node ligation models were then performed in 20 adult male Sprague-Dawley rats. The brains were scanned in vivo dynamically after surgery using the new MRI method. Behavioral tests were performed after each scanning session and the results were tested for correlations with the MRI signal intensity. Finally, the pathological assessment was conducted in the same brain slices. The special MRI effect in the lymph was evident at about 1.0 ppm in water and was distinguishable from those of blood and CSF. In the model group, the intensity of this MRI signal was significantly higher in the ipsilateral than in the contralateral hippocampus. The correlation between the signal abnormality and the behavioral score was significant (Pearson's, R2 = 0.9154, p < 0.005). We conclude that the novel MRI method can visualize the glymphatic system in vivo.
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Affiliation(s)
- Yuanfeng Chen
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
| | - Zhuozhi Dai
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
| | - Ruhang Fan
- Department of Pathology, Medical College of Shantou University, Guangdong, Shantou 515031, P.R. China
| | - David John Mikulis
- Division of Neuroradiology, Department of Medical Imaging, University Health Network, Toronto, Ontario M5T 2S7, Canada
| | - Jinming Qiu
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
| | - Zhiwei Shen
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
| | - Runrun Wang
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
| | - Lihua Lai
- Department of Radiology, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, P. R. China
| | - Yanyan Tang
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
| | - Yan Li
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
| | - Yanlong Jia
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
| | - Gen Yan
- Department of Radiology, the Second Affiliated Hospital of Xiamen Medical College, Xiamen, Fujian Province 361022, China
| | - Renhua Wu
- Department of Radiology, the Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, P.R. China
- Provincial Key Laboratory of Medical Molecular Imaging, Guangdong, Shantou 515041, P.R. China
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13
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Mueller S, Stirnberg R, Akbey S, Ehses P, Scheffler K, Stöcker T, Zaiss M. Whole brain snapshot CEST at 3T using 3D‐EPI: Aiming for speed, volume, and homogeneity. Magn Reson Med 2020; 84:2469-2483. [DOI: 10.1002/mrm.28298] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 03/16/2020] [Accepted: 04/02/2020] [Indexed: 12/18/2022]
Affiliation(s)
- Sebastian Mueller
- High‐field Magnetic Resonance Center Max Planck Institute for Biological Cybernetics Tuebingen Germany
| | | | - Suzan Akbey
- German Center for Neurodegenerative Diseases (DZNE) Bonn Germany
| | - Philipp Ehses
- German Center for Neurodegenerative Diseases (DZNE) Bonn Germany
| | - Klaus Scheffler
- High‐field Magnetic Resonance Center Max Planck Institute for Biological Cybernetics Tuebingen Germany
- Department of Biomedical Magnetic Resonance Eberhard Karls University Tuebingen Tuebingen Germany
| | - Tony Stöcker
- German Center for Neurodegenerative Diseases (DZNE) Bonn Germany
- Department of Physics and Astronomy University of Bonn Bonn Germany
| | - Moritz Zaiss
- High‐field Magnetic Resonance Center Max Planck Institute for Biological Cybernetics Tuebingen Germany
- Department of Neuroradiology University Hospital Erlangen Erlangen Germany
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14
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Common and dissociable effects of oxytocin and lorazepam on the neurocircuitry of fear. Proc Natl Acad Sci U S A 2020; 117:11781-11787. [PMID: 32385158 DOI: 10.1073/pnas.1920147117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Benzodiazepines (BZDs) represent the gold standard of anxiolytic pharmacotherapy; however, their clinical benefit is limited by side effects and addictive potential. Consequently, there is an urgent need to develop novel and safe anxiolytics. The peptide hormone oxytocin (OXT) exhibits anxiolytic-like properties in animals and humans, but whether OXT and BZDs share similar effects on the neural circuitry of fear is unclear. Therefore, the rationale of this ultra-high-field functional MRI (fMRI) study was to test OXT against the clinical comparator lorazepam (LZP) with regard to their neuromodulatory effects on local and network responses to fear-related stimuli. One hundred twenty-eight healthy male participants volunteered in this randomized double-blind, placebo-controlled, between-group study. Before scanning using an emotional face-matching paradigm, participants were randomly administered a single dose of OXT (24 IU), LZP (1 mg), or placebo. On the behavioral level, LZP, but not OXT, caused mild sedation, as evidenced by a 19% increase in reaction times. On the neural level, both OXT and LZP inhibited responses to fearful faces vs. neutral faces within the centromedial amygdala (cmA). In contrast, they had different effects on intra-amygdalar connectivity; OXT strengthened the coupling between the cmA and basolateral amygdala, whereas LZP increased the interplay between the cmA and superficial amygdala. Furthermore, OXT, but not LZP, enhanced the coupling between the cmA and the precuneus and dorsomedial prefrontal cortex. These data implicate inhibition of the cmA as a common denominator of anxiolytic action, with only OXT inducing large-scale connectivity changes of potential therapeutic relevance.
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Norbeck O, Sprenger T, Avventi E, Rydén H, Kits A, Berglund J, Skare S. Optimizing 3D EPI for rapid T
1
‐weighted imaging. Magn Reson Med 2020; 84:1441-1455. [DOI: 10.1002/mrm.28222] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 01/14/2020] [Accepted: 01/29/2020] [Indexed: 01/17/2023]
Affiliation(s)
- Ola Norbeck
- Department of Neuroradiology Karolinska University Hospital Stockholm Sweden
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
| | - Tim Sprenger
- MR Applied Science Laboratory Europe, GE Healthcare Stockholm Sweden
| | - Enrico Avventi
- Department of Neuroradiology Karolinska University Hospital Stockholm Sweden
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
| | - Henric Rydén
- Department of Neuroradiology Karolinska University Hospital Stockholm Sweden
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
| | - Annika Kits
- Department of Neuroradiology Karolinska University Hospital Stockholm Sweden
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
| | - Johan Berglund
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
| | - Stefan Skare
- Department of Neuroradiology Karolinska University Hospital Stockholm Sweden
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
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16
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Comparison of SMS-EPI and 3D-EPI at 7T in an fMRI localizer study with matched spatiotemporal resolution and homogenized excitation profiles. PLoS One 2019; 14:e0225286. [PMID: 31751410 PMCID: PMC6872176 DOI: 10.1371/journal.pone.0225286] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/31/2019] [Indexed: 02/06/2023] Open
Abstract
The simultaneous multi-slice EPI (SMS-EPI, a.k.a. MB-EPI) sequence has met immense popularity recently in functional neuroimaging. A still less common alternative is the use of 3D-EPI, which offers similar acceleration capabilities. The aim of this work was to compare the SMS-EPI and the 3D-EPI sequences in terms of sampling strategies for the detection of task-evoked activations at 7T using detection theory. To this end, the spatial and temporal resolutions of the sequences were matched (1.6 mm isotropic resolution, TR = 1200 ms) and their excitation profiles were homogenized by means of calibration-free parallel-transmission (Universal Pulses). We used a fast-event “localizer” paradigm of 5:20 min in order to probe sensorimotor functions (visual, auditory and motor tasks) as well as higher level functions (language comprehension, mental calculation), where results from a previous large-scale study at 3T (N = 81) served as ground-truth reference for the brain areas implicated in each cognitive function. In the current study, ten subjects were scanned while their activation maps were generated for each cognitive function with the GLM analysis. The SMS-EPI and 3D-EPI sequences were compared in terms of raw tSNR, t-score testing for the mean signal, activation strength and accuracy of the robust sensorimotor functions. To this end, the sensitivity and specificity of these contrasts were computed by comparing their activation maps to the reference brain areas obtained in the 3T study. Estimated flip angle distributions in the brain reported a normalized root mean square deviation from the target value below 10% for both sequences. The analysis of the t-score testing for the mean signal revealed temporal noise correlations, suggesting the use of this metric instead of the traditional tSNR for testing fMRI sequences. The SMS-EPI and 3D-EPI thereby yielded similar performance from a detection theory perspective.
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17
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Wang R, Wang C, Dai Z, Chen Y, Shen Z, Xiao G, Chen Y, Zhou JN, Zhuang Z, Wu R. An Amyloid-β Targeting Chemical Exchange Saturation Transfer Probe for In Vivo Detection of Alzheimer's Disease. ACS Chem Neurosci 2019; 10:3859-3867. [PMID: 31343167 DOI: 10.1021/acschemneuro.9b00334] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A reliable and reproducible detection of Aβ deposits would be beneficial for the early diagnosis of Alzheimer's disease (AD). In the present study, the feasibility of applying chemical exchange saturation transfer (CEST) for Aβ deposit detection using angiopep-2 as a probe was evaluated, and it was demonstrated that CEST could detect angiopep-2 and Aβ-angiopep-2 aggregates in vitro. Furthermore, APP/PS1 mice injected with angiopep-2 exhibited a significantly higher in vivo CEST effect when compared with controls. The distribution of Aβ deposits detected by CEST imaging was consistent with the histological staining results. The present study is the first to report a reliable exogenous CEST probe to noninvasively evaluate Aβ deposits in APP/PS1 mice. Furthermore, these results demonstrate the potential for clinical AD diagnosis and Aβ-targeted drug therapy assessment using CEST imaging with the angiopep-2 probe.
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Affiliation(s)
- Runrun Wang
- Department of Medical Imaging, Second Affiliated Hospital , Shantou University Medical College , Shantou , Guangdong 515000 , P. R. China
| | - Chenwei Wang
- CAS Key Laboratory of Brain Function and Disease, School of Life Sciences , University of Science and Technology of China , Hefei , Anhui 230000 , P. R. China
| | - Zhuozhi Dai
- Department of Medical Imaging, Second Affiliated Hospital , Shantou University Medical College , Shantou , Guangdong 515000 , P. R. China
| | - Yanzi Chen
- Department of Medical Imaging, Second Affiliated Hospital , Shantou University Medical College , Shantou , Guangdong 515000 , P. R. China
| | - Zhiwei Shen
- Department of Medical Imaging, Second Affiliated Hospital , Shantou University Medical College , Shantou , Guangdong 515000 , P. R. China
| | - Gang Xiao
- Department of Mathematics and Statistics , Hanshan Normal University , Chaozhou 515000 , P. R. China
| | - Yuanfeng Chen
- Department of Medical Imaging, Second Affiliated Hospital , Shantou University Medical College , Shantou , Guangdong 515000 , P. R. China
| | - Jiang-Ning Zhou
- CAS Key Laboratory of Brain Function and Disease, School of Life Sciences , University of Science and Technology of China , Hefei , Anhui 230000 , P. R. China
- Center for Excellence in Brain Science and Intelligence Technology , Chinese Academy of Sciences , Shanghai 200031 , China
| | - Zerui Zhuang
- Department of Medical Imaging, Second Affiliated Hospital , Shantou University Medical College , Shantou , Guangdong 515000 , P. R. China
| | - Renhua Wu
- Department of Medical Imaging, Second Affiliated Hospital , Shantou University Medical College , Shantou , Guangdong 515000 , P. R. China
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18
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Akbey S, Ehses P, Stirnberg R, Zaiss M, Stöcker T. Whole‐brain snapshot CEST imaging at 7 T using 3D‐EPI. Magn Reson Med 2019; 82:1741-1752. [DOI: 10.1002/mrm.27866] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/06/2019] [Accepted: 05/24/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Suzan Akbey
- German Center for Neurodegenerative Diseases (DZNE) Bonn Germany
| | - Philipp Ehses
- German Center for Neurodegenerative Diseases (DZNE) Bonn Germany
| | | | - Moritz Zaiss
- Max‐Planck Institute for Biological Cybernetics Tübingen Germany
| | - Tony Stöcker
- German Center for Neurodegenerative Diseases (DZNE) Bonn Germany
- Department of Physics and Astronomy University of Bonn Bonn Germany
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19
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Hybrid MR-PET of brain tumours using amino acid PET and chemical exchange saturation transfer MRI. Eur J Nucl Med Mol Imaging 2018; 45:1031-1040. [PMID: 29478081 DOI: 10.1007/s00259-018-3940-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 01/04/2018] [Indexed: 10/18/2022]
Abstract
PURPOSE PET using radiolabelled amino acids has become a promising tool in the diagnostics of gliomas and brain metastasis. Current research is focused on the evaluation of amide proton transfer (APT) chemical exchange saturation transfer (CEST) MR imaging for brain tumour imaging. In this hybrid MR-PET study, brain tumours were compared using 3D data derived from APT-CEST MRI and amino acid PET using O-(2-18F-fluoroethyl)-L-tyrosine (18F-FET). METHODS Eight patients with gliomas were investigated simultaneously with 18F-FET PET and APT-CEST MRI using a 3-T MR-BrainPET scanner. CEST imaging was based on a steady-state approach using a B1 average power of 1μT. B0 field inhomogeneities were corrected a Prametric images of magnetisation transfer ratio asymmetry (MTRasym) and differences to the extrapolated semi-solid magnetisation transfer reference method, APT# and nuclear Overhauser effect (NOE#), were calculated. Statistical analysis of the tumour-to-brain ratio of the CEST data was performed against PET data using the non-parametric Wilcoxon test. RESULTS A tumour-to-brain ratio derived from APT# and 18F-FET presented no significant differences, and no correlation was found between APT# and 18F-FET PET data. The distance between local hot spot APT# and 18F-FET were different (average 20 ± 13 mm, range 4-45 mm). CONCLUSION For the first time, CEST images were compared with 18F-FET in a simultaneous MR-PET measurement. Imaging findings derived from18F-FET PET and APT CEST MRI seem to provide different biological information. The validation of these imaging findings by histological confirmation is necessary, ideally using stereotactic biopsy.
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20
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Bastiaansen JA, Stuber M. Flexible water excitation for fat-free MRI at 3T using lipid insensitive binomial off-resonant RF excitation (LIBRE) pulses. Magn Reson Med 2017; 79:3007-3017. [DOI: 10.1002/mrm.26965] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/11/2017] [Accepted: 09/21/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Jessica A.M. Bastiaansen
- Department of Radiology; University Hospital (CHUV) and University of Lausanne (UNIL); Lausanne Switzerland
| | - Matthias Stuber
- Department of Radiology; University Hospital (CHUV) and University of Lausanne (UNIL); Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
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21
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Stirnberg R, Huijbers W, Brenner D, Poser BA, Breteler M, Stöcker T. Rapid whole-brain resting-state fMRI at 3 T: Efficiency-optimized three-dimensional EPI versus repetition time-matched simultaneous-multi-slice EPI. Neuroimage 2017; 163:81-92. [PMID: 28923276 DOI: 10.1016/j.neuroimage.2017.08.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/28/2017] [Accepted: 08/09/2017] [Indexed: 01/18/2023] Open
Abstract
State-of-the-art simultaneous-multi-slice (SMS-)EPI and 3D-EPI share several properties that benefit functional MRI acquisition. Both sequences employ equivalent parallel imaging undersampling with controlled aliasing to achieve high temporal sampling rates. As a volumetric imaging sequence, 3D-EPI offers additional means of acceleration complementary to 2D-CAIPIRINHA sampling, such as fast water excitation and elliptical sampling. We performed an application-oriented comparison between a tailored, six-fold CAIPIRINHA-accelerated 3D-EPI protocol at 530 ms temporal and 2.4 mm isotropic spatial resolution and an SMS-EPI protocol with identical spatial and temporal resolution for whole-brain resting-state fMRI at 3 T. The latter required eight-fold slice acceleration to compensate for the lack of elliptical sampling and fast water excitation. Both sequences used vendor-supplied on-line image reconstruction. We acquired test/retest resting-state fMRI scans in ten volunteers, with simultaneous acquisition of cardiac and respiration data, subsequently used for optional physiological noise removal (nuisance regression). We found that the 3D-EPI protocol has significantly increased temporal signal-to-noise ratio throughout the brain as compared to the SMS-EPI protocol, especially when employing motion and nuisance regression. Both sequence types reliably identified known functional networks with stronger functional connectivity values for the 3D-EPI protocol. We conclude that the more time-efficient 3D-EPI primarily benefits from reduced parallel imaging noise due to a higher, actual k-space sampling density compared to SMS-EPI. The resultant BOLD sensitivity increase makes 3D-EPI a valuable alternative to SMS-EPI for whole-brain fMRI at 3 T, with voxel sizes well below 3 mm isotropic and sampling rates high enough to separate dominant cardiac signals from BOLD signals in the frequency domain.
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Affiliation(s)
| | - Willem Huijbers
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; Jheronimus Academy of Data Science, Cognitive Science and Artificial Intelligence, Tilburg University, The Netherlands
| | - Daniel Brenner
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Benedikt A Poser
- Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Monique Breteler
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Tony Stöcker
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; Department of Physics and Astronomy, University of Bonn, Bonn, Germany
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