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Ma L, Cai C, Yang H, Cai S, Qian J, Xiao L, Zhong K, Chen Z. Motion-tolerant diffusion mapping based on single-shot overlapping-echo detachment (OLED) planar imaging. Magn Reson Med 2017; 80:200-210. [DOI: 10.1002/mrm.27023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 10/31/2017] [Accepted: 11/01/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Lingceng Ma
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance; Xiamen University; Xiamen China
| | - Congbo Cai
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance; Xiamen University; Xiamen China
- Department of Communication Engineering; Xiamen University; Xiamen China
| | - Hongyi Yang
- High Magnet Field Laboratory, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences; Hefei China
| | - Shuhui Cai
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance; Xiamen University; Xiamen China
| | - Junchao Qian
- High Magnet Field Laboratory, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences; Hefei China
| | - Lizhi Xiao
- State Key Laboratory of Petroleum Resources and Prospecting; China University of Petroleum; Beijing China
| | - Kai Zhong
- High Magnet Field Laboratory, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences; Hefei China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance; Xiamen University; Xiamen China
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Nicolas R, Gros-Dagnac H, Aubry F, Celsis P. Comparison of BOLD, diffusion-weighted fMRI and ADC-fMRI for stimulation of the primary visual system with a block paradigm. Magn Reson Imaging 2017; 39:123-131. [PMID: 28163122 DOI: 10.1016/j.mri.2017.01.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 10/20/2022]
Abstract
The blood oxygen level-dependent (BOLD) effect is extensively used for functional MRI (fMRI) but presents some limitations. Diffusion-weighted fMRI (DfMRI) has been proposed as a method more tightly linked to neuronal activity. This work proposes a protocol of DfMRI acquired for several b-values and diffusion directions that is compared to gradient-echo BOLD (GE-BOLD) and to repeated spin-echo BOLD (SE-BOLD, acquisitions performed with b=0s/mm2), which was also used to ensure the reproducibility of the response. A block stimulation paradigm of the primary visual system (V1) was performed in 12 healthy subjects with checkerboard alternations (2Hz frequency). DfMRI was performed at 3T with 5 b-values (b=1500, 1000, 500, 250, 0s/mm2) with TR/TE=1004/93ms, Δ/δ=45.4ms/30ms, and 6 spatial directions for diffusion measures. GE-BOLD was performed with a similar block stimulation design timing. Apparent Diffusion Coefficient (ADC)-fMRI was computed with all b-values used. An identical Z-score level was used for all fMRI modalities for the comparison of volumes of activation. ADC-fMRI and SE-BOLD fMRI activation locations were compared in a voxel-based analysis to a cytoarchitectural probability map of V1. SE-BOLD activation volumes represented only 55% of the GE-BOLD activation volumes (P<0.0001). DfMRI activation volumes averaged for all b-values acquired represented only 12% of GE-BOLD (P<0.0001) and only 22% of SE-BOLD activation volumes (P<0.005). Compared to SE-BOLD-fMRI, ADC-fMRI activations showed fewer pixels outside of V1 and a higher average probability of belonging to V1. DfMRI and ADC-fMRI acquisition at 3T could be easily post-processed with common neuro-imaging software. DfMRI and ADC-fMRI activation volumes were significantly smaller than those obtained with SE-BOLD. ADC-fMRI activations were more precisely localized in V1 than those of SE-BOLD-fMRI. This validated the increased capability of ADC-fMRI compared to BOLD to enhance the precision of localizing an fMRI activation in the cyto-architectural zone V1, thereby justifying the use of ADC-fMRI for neuro-scientific studies.
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Affiliation(s)
- R Nicolas
- Imagerie cérébrale et handicaps neurologiques, INSERM Université de Toulouse (UMR 825), F-31059 Toulouse, France; Aquitaine Institute for Cognitive and Integrative Neuroscience (INCIA), CNRS Université Bordeaux 2 (UMR 5287), F-33400 Talence, France; ARCANI, 27, rue fonfrède (N° SIRET: 803 234 715 00016), F-33800 Bordeaux, France.
| | - H Gros-Dagnac
- Imagerie cérébrale et handicaps neurologiques, INSERM Université de Toulouse (UMR 825), F-31059 Toulouse, France
| | - F Aubry
- Imagerie cérébrale et handicaps neurologiques, INSERM Université de Toulouse (UMR 825), F-31059 Toulouse, France
| | - P Celsis
- Imagerie cérébrale et handicaps neurologiques, INSERM Université de Toulouse (UMR 825), F-31059 Toulouse, France
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Abstract
Measurements of water molecule diffusion along fiber tracts in CNS by diffusion tensor imaging (DTI) provides a static map of neural connections between brain centers, but does not capture the electrical activity along axons for these fiber tracts. Here, a modification of the DTI method is presented to enable the mapping of active fibers. It is termed dynamic diffusion tensor imaging (dDTI) and is based on a hypothesized “anisotropy reduction due to axonal excitation” (“AREX”). The potential changes in water mobility accompanying the movement of ions during the propagation of action potentials along axonal tracts are taken into account. Specifically, the proposed model, termed “ionic DTI model”, was formulated as follows.First, based on theoretical calculations, we calculated the molecular water flow accompanying the ionic flow perpendicular to the principal axis of fiber tracts produced by electrical conduction along excited myelinated and non-myelinated axons. Based on the changes in molecular water flow we estimated the signal changes as well as the changes in fractional anisotropy of axonal tracts while performing a functional task. The variation of fractional anisotropy in axonal tracts could allow mapping the active fiber tracts during a functional task.
Although technological advances are necessary to enable the robust and routine measurement of this electrical activity-dependent movement of water molecules perpendicular to axons, the proposed model of dDTI defines the vectorial parameters that will need to be measured to bring this much needed technique to fruition.
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Affiliation(s)
- Nikos Makris
- Harvard Medical School, Department of Psychiatry, Center for Morphometric Analysis, HST Athinoula A. Martinos Center, Massachusetts General Hospital, Boston, MA 02129, USA
- Harvard Medical School, Department of Neurology, Center for Morphometric Analysis, HST Athinoula A. Martinos Center, Massachusetts General Hospital, Boston, MA 02129, USA
- Corresponding author at: Massachusetts General Hospital, Center for Morphometric Analysis, Building 149, 13th Street, Office 10.006, Charlestown, MA 02129, USA. Tel.: +1 617 726 5733; fax: +1 617 726 5711.
| | - Gregory P. Gasic
- Harvard Medical School, Department of Radiology, HST Athinoula A. Martinos Center, Massachusetts General Hospital, Boston, MA 02129, USA
| | - Leoncio Garrido
- Department of Physical Chemistry, Instituto de Ciencia y Tecnología de Polímeros, Consejo Superior de Investigaciones Científicas (ICTP-CSIC), Juan de la Cierva 3, E-28006 Madrid, Spain
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Balasubramanian M, Mulkern RV, Wells WM, Sundaram P, Orbach DB. Magnetic resonance imaging of ionic currents in solution: the effect of magnetohydrodynamic flow. Magn Reson Med 2014; 74:1145-55. [PMID: 25273917 DOI: 10.1002/mrm.25445] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 07/25/2014] [Accepted: 08/15/2014] [Indexed: 11/06/2022]
Abstract
PURPOSE Reliably detecting MRI signals in the brain that are more tightly coupled to neural activity than blood-oxygen-level-dependent fMRI signals could not only prove valuable for basic scientific research but could also enhance clinical applications such as epilepsy presurgical mapping. This endeavor will likely benefit from an improved understanding of the behavior of ionic currents, the mediators of neural activity, in the presence of the strong magnetic fields that are typical of modern-day MRI scanners. THEORY Of the various mechanisms that have been proposed to explain the behavior of ionic volume currents in a magnetic field, only one-magnetohydrodynamic flow-predicts a slow evolution of signals, on the order of a minute for normal saline in a typical MRI scanner. METHODS This prediction was tested by scanning a volume-current phantom containing normal saline with gradient-echo-planar imaging at 3 T. RESULTS Greater signal changes were observed in the phase of the images than in the magnitude, with the changes evolving on the order of a minute. CONCLUSION These results provide experimental support for the MHD flow hypothesis. Furthermore, MHD-driven cerebrospinal fluid flow could provide a novel fMRI contrast mechanism.
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Affiliation(s)
- Mukund Balasubramanian
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Robert V Mulkern
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - William M Wells
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Padmavathi Sundaram
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Darren B Orbach
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Mulkern RV, Haker SJ, Maier SE. On high b diffusion imaging in the human brain: ruminations and experimental insights. Magn Reson Imaging 2009; 27:1151-62. [PMID: 19520535 PMCID: PMC2894527 DOI: 10.1016/j.mri.2009.05.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 02/20/2009] [Accepted: 05/06/2009] [Indexed: 01/23/2023]
Abstract
Interest in the manner in which brain tissue signal decays with b factor in diffusion imaging schemes has grown in recent years following the observation that the decay curves depart from purely monoexponential decay behavior. Regardless of the model or fitting function proposed for characterizing sufficiently sampled decay curves (vide infra), the departure from monoexponentiality spells increased tissue characterization potential. The degree to which this potential can be harnessed to improve specificity, sensitivity and spatial localization of diseases in brain, and other tissues, largely remains to be explored. Furthermore, the degree to which currently popular diffusion tensor imaging methods, including visually impressive white matter fiber "tractography" results, have almost completely ignored the nonmonoexponential nature of the basic signal decay with b factor is worthy of communal introspection. Here we limit our attention to a review of the basic experimental features associated with brain water signal diffusion decay curves as measured over extended b-factor ranges, the simple few parameter fitting functions that have been proposed to characterize these decays and the more involved models, e.g.,"ruminations," which have been proposed to account for the nonmonoexponentiality to date.
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Affiliation(s)
- Robert V. Mulkern
- Department of Radiology, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Steven J. Haker
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Stephan E. Maier
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Sutton BP, Ouyang C, Karampinos DC, Miller GA. Current trends and challenges in MRI acquisitions to investigate brain function. Int J Psychophysiol 2009; 73:33-42. [PMID: 19236896 DOI: 10.1016/j.ijpsycho.2008.12.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 12/08/2008] [Accepted: 12/23/2008] [Indexed: 11/19/2022]
Abstract
Functional magnetic resonance imaging (fMRI) studies using the blood oxygenation level dependent (BOLD) response have become a widely used tool for noninvasive assessment of functional organization of the brain. Yet the technique is still fairly new, with many significant challenges remaining. Capitalizing on additional contrast mechanisms available with MRI, several other functional imaging techniques have been developed that potentially provide improved quantification or specificity of neuronal function. This article reviews the challenges and the current state of the art in MRI-based methods of imaging cognitive function.
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Affiliation(s)
- Bradley P Sutton
- Bioengineering Department, University of Illinois at Urbana-Champaign, 3120 DCL, 1304 W Springfield Avenue, Urbana, IL 61801 United States.
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