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Miao X, Li Y, Zhou X, Luo Y, Paez AG, Liu D, van Zijl PCM, Hua J. Evaluation of T2-prepared blood oxygenation level dependent functional magnetic resonance imaging with an event-related task: Hemodynamic response function and reproducibility. Front Neurosci 2023; 17:1114045. [PMID: 36937683 PMCID: PMC10017524 DOI: 10.3389/fnins.2023.1114045] [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: 12/02/2022] [Accepted: 02/13/2023] [Indexed: 03/06/2023] Open
Abstract
T2-prepared (T2prep) blood oxygenation level dependent (BOLD) functional MRI (fMRI) is an alternative fMRI approach developed to mitigate the susceptibility artifacts that are typically observed in brain regions near air-filled cavities, bleeding and calcification, and metallic objects in echo-planar-imaging (EPI) based fMRI images. Here, T2prep BOLD fMRI was evaluated in an event-related paradigm for the first time. Functional experiments were performed using gradient-echo (GRE) EPI, spin-echo (SE) EPI, and T2prep BOLD fMRI during an event-related visual task in 10 healthy human subjects. Each fMRI method was performed with a low (3.4 × 3.4 × 4 mm3) and a high (1.5 mm isotropic) spatial resolution on 3T and a high resolution (1.5 mm isotropic) on 7T. Robust activation were detected in the visual cortex with all three fMRI methods. In each group of fMRI scans (3T low resolution, 3T high resolution, and 7T high resolution), GRE EPI showed the highest signal change (ΔS/S), largest full-width-at-half-maximum (FWHM) and longest time-to-peak (TTP) extracted from the hemodynamic response functions (HRF), indicating substantial signal contribution from large draining veins which have longer response times than microvessels. In contrast, T2prep BOLD showed the lowest ΔS/S, smallest FWHM, and shortest TTP, suggesting that T2prep BOLD may have a purer T2-weighted BOLD contrast that is more sensitive to microvessels compared to GRE/SE EPI BOLD. This trend was more obvious in fMRI scans performed with a lower spatial resolution on a lower field (3T with a 3.4 × 3.4 × 4 mm3 voxel). Scan-rescan reproducibility in the same subjects was comparable among the three fMRI methods. The results from the current study are expected to be useful to establish T2prep BOLD as a useful alternative fMRI approach for event-related fMRI in brain regions with large susceptibility artifacts.
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Affiliation(s)
- Xinyuan Miao
- Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
| | - Yinghao Li
- Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Xinyi Zhou
- Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Yu Luo
- Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
| | - Adrian G. Paez
- Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
| | - Dapeng Liu
- Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
| | - Peter C. M. van Zijl
- Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
| | - Jun Hua
- Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
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Kim JH, Taylor AJ, Himmelbach M, Hagberg GE, Scheffler K, Ress D. Characterization of the blood oxygen level dependent hemodynamic response function in human subcortical regions with high spatiotemporal resolution. Front Neurosci 2022; 16:1009295. [PMID: 36303946 PMCID: PMC9592726 DOI: 10.3389/fnins.2022.1009295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Subcortical brain regions are absolutely essential for normal human function. These phylogenetically early brain regions play critical roles in human behaviors such as the orientation of attention, arousal, and the modulation of sensory signals to cerebral cortex. Despite the critical health importance of subcortical brain regions, there has been a dearth of research on their neurovascular responses. Blood oxygen level dependent (BOLD) functional MRI (fMRI) experiments can help fill this gap in our understanding. The BOLD hemodynamic response function (HRF) evoked by brief (<4 s) neural activation is crucial for the interpretation of fMRI results because linear analysis between neural activity and the BOLD response relies on the HRF. Moreover, the HRF is a consequence of underlying local blood flow and oxygen metabolism, so characterization of the HRF enables understanding of neurovascular and neurometabolic coupling. We measured the subcortical HRF at 9.4T and 3T with high spatiotemporal resolution using protocols that enabled reliable delineation of HRFs in individual subjects. These results were compared with the HRF in visual cortex. The HRF was faster in subcortical regions than cortical regions at both field strengths. There was no significant undershoot in subcortical areas while there was a significant post-stimulus undershoot that was tightly coupled with its peak amplitude in cortex. The different BOLD temporal dynamics indicate different vascular dynamics and neurometabolic responses between cortex and subcortical nuclei.
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Affiliation(s)
- Jung Hwan Kim
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Amanda J. Taylor
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Marc Himmelbach
- Division of Neuropsychology, Center of Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Gisela E. Hagberg
- High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Department of Biomedical Magnetic Resonance, Eberhard Karl’s University of Tübingen and University Hospital, Tübingen, Germany
| | - Klaus Scheffler
- High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Department of Biomedical Magnetic Resonance, Eberhard Karl’s University of Tübingen and University Hospital, Tübingen, Germany
| | - David Ress
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
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Yin Y, Shu S, Qin L, Shan Y, Gao JH, Lu J. Effects of mild hypoxia on oxygen extraction fraction responses to brain stimulation. J Cereb Blood Flow Metab 2021; 41:2216-2228. [PMID: 33563081 PMCID: PMC8393298 DOI: 10.1177/0271678x21992896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Characterizing the effect of limited oxygen availability on brain metabolism during brain activation is an essential step towards a better understanding of brain homeostasis and has obvious clinical implications. However, how the cerebral oxygen extraction fraction (OEF) depends on oxygen availability during brain activation remains unclear, which is mostly attributable to the scarcity and safety of measurement techniques. Recently, a magnetic resonance imaging (MRI) method that enables noninvasive and dynamic measurement of the OEF has been developed and confirmed to be applicable to functional MRI studies. Using this novel method, the present study investigated the motor-evoked OEF response in both normoxia (21% O2) and hypoxia (12% O2). Our results showed that OEF activation decreased in the brain areas involved in motor task execution. Decreases in the motor-evoked OEF response were greater under hypoxia (-21.7% ± 5.5%) than under normoxia (-11.8% ± 3.7%) and showed a substantial decrease as a function of arterial oxygen saturation. These findings suggest a different relationship between oxygen delivery and consumption during hypoxia compared to normoxia. This methodology may provide a new perspective on the effects of mild hypoxia on brain function.
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Affiliation(s)
- Yayan Yin
- Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Magnetic Resonance Imaging and Brain Informatics, Beijing, China
| | - Su Shu
- Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.,Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Lang Qin
- Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.,Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Yi Shan
- Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Magnetic Resonance Imaging and Brain Informatics, Beijing, China
| | - Jia-Hong Gao
- Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.,Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.,McGovern Institution for Brain Research, Peking University, Beijing, China
| | - Jie Lu
- Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Magnetic Resonance Imaging and Brain Informatics, Beijing, China.,Department of Nuclear Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
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4
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Markuerkiaga I, Marques JP, Gallagher TE, Norris DG. Estimation of laminar BOLD activation profiles using deconvolution with a physiological point spread function. J Neurosci Methods 2021; 353:109095. [PMID: 33549635 DOI: 10.1016/j.jneumeth.2021.109095] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 12/30/2020] [Accepted: 01/31/2021] [Indexed: 02/05/2023]
Abstract
BACKGROUND The specificity of gradient echo (GE)-BOLD laminar fMRI activation profiles is degraded by intracortical veins that drain blood from lower to upper cortical layers, propagating activation signal in the same direction. This work describes an approach to obtain layer specific profiles by deconvolving the measured profiles with a physiological Point Spread Function (PSF). NEW METHOD It is shown that the PSF can be characterised by a TE-dependent peak to tail (p2t) value that is independent of cortical depth and can be estimated by simulation. An experimental estimation of individual p2t values and the sensitivity of the deconvolved profiles to variations in p2t is obtained using laminar data measured with a multi-echo 3D-FLASH sequence. These profiles are echo time dependent, but the underlying neuronal response is the same, allowing a data-based estimation of the PSF. RESULTS The deconvolved profiles are highly similar to the gold-standard obtained from extremely high resolution 3D-EPI data, for a range of p2t values of 5-9, which covers both the empirically determined value (6.8) and the value obtained by simulation (6.3). -Comparison with Existing Method(s) Corrected profiles show a flatter shape across the cortex and a high level of similarity with the gold-standard, defined as a subset of profiles that are unaffected by intracortical veins. CONCLUSIONS We conclude that deconvolution is a robust approach for removing the effect of signal propagation through intracortical veins. This makes it possible to obtain profiles with high laminar specificity while benefitting from the higher efficiency of GE-BOLD sequences.
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Affiliation(s)
- Irati Markuerkiaga
- Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, the Netherlands
| | - José P Marques
- Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, the Netherlands
| | - Tara E Gallagher
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, USA
| | - David G Norris
- Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, the Netherlands; Erwin L. Hahn Institute for Magnetic Resonance Imaging, 45141, Essen, Germany.
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Markuerkiaga I, Marques JP, Bains LJ, Norris DG. An in-vivo study of BOLD laminar responses as a function of echo time and static magnetic field strength. Sci Rep 2021; 11:1862. [PMID: 33479362 PMCID: PMC7820587 DOI: 10.1038/s41598-021-81249-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 12/22/2020] [Indexed: 11/18/2022] Open
Abstract
Layer specific functional MRI requires high spatial resolution data. To compensate the associated poor signal to noise ratio it is common to integrate the signal from voxels at a given cortical depth. If the region is sufficiently large then physiological noise will be the dominant noise source. In this work, activation profiles in response to the same visual stimulus are compared at 1.5 T, 3 T and 7 T using a multi-echo, gradient echo (GE) FLASH sequence, with a 0.75 mm isotropic voxel size and the cortical integration approach. The results show that after integrating over a cortical volume of 40, 60 and 100 mm3 (at 7 T, 3 T, and 1.5 T, respectively), the signal is in the physiological noise dominated regime. The activation profiles obtained are similar for equivalent echo times. BOLD-like noise is found to be the dominant source of physiological noise. Consequently, the functional contrast to noise ratio is not strongly echo-time or field-strength dependent. We conclude that laminar GE-BOLD fMRI at lower field strengths is feasible but that larger patches of cortex will need to be examined, and that the acquisition efficiency is reduced.
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Affiliation(s)
- Irati Markuerkiaga
- Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, The Netherlands
| | - José P Marques
- Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, The Netherlands
| | - Lauren J Bains
- Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, The Netherlands
| | - David G Norris
- Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, The Netherlands. .,Erwin L. Hahn Institute for Magnetic Resonance Imaging, 45141, Essen, Germany.
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Genois É, Gagnon L, Desjardins M. Modeling of vascular space occupancy and BOLD functional MRI from first principles using real microvascular angiograms. Magn Reson Med 2020; 85:456-468. [PMID: 32726489 DOI: 10.1002/mrm.28429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 05/29/2020] [Accepted: 06/23/2020] [Indexed: 11/07/2022]
Abstract
PURPOSE The vascular space occupancy (VASO) is a functional MRI technique for probing cerebral blood volume changes noninvasively, including during neuronal activation in humans. An important consideration when implementing VASO is the BOLD effect in the signal. Assessing the physical origin of this BOLD contamination and the capabilities of correction methods could improve the quantification of cerebral blood volume changes with VASO. METHODS Given the heterogeneity of cerebral microvascular architecture, the vascular geometry within an MRI voxel can influence both BOLD and VASO signals. To investigate this effect, 3D high-resolution images of mouse cerebral vasculature measured with two-photon microscopy were used to model BOLD and VASO signals from first principles using Monte Carlo diffusion of water protons. Quantitative plots of VASO together with intravascular and extravascular BOLD signals as a function of TE at B0 fields 1.5 T to 14 T were obtained. RESULTS The BOLD contamination of the VASO response was on the order of 50% for gradient echo and 5% for spin echo at 7 T and TE = 6 ms and significantly increased with TE and B0 . Two currently used correction schemes were shown to account for most of this contamination and recover accurate relative signal changes, with optimal correction obtained using TEs as short as possible. CONCLUSION These results may provide useful information for optimizing sequence parameters in VASO and BOLD functional MRI, leading the way to a wider application of these techniques in healthy and diseased brain.
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Affiliation(s)
- Élie Genois
- Department of Physics, Engineering Physics and Optics, Université Laval, Québec, Canada.,Oncology Division, Centre de Recherche du CHU de Québec - Université Laval, Québec, Canada
| | - Louis Gagnon
- Department of Physics, Engineering Physics and Optics, Université Laval, Québec, Canada.,Oncology Division, Centre de Recherche du CHU de Québec - Université Laval, Québec, Canada.,Department of Radiology and Nuclear Medicine, Université Laval, Québec, Canada
| | - Michèle Desjardins
- Department of Physics, Engineering Physics and Optics, Université Laval, Québec, Canada.,Oncology Division, Centre de Recherche du CHU de Québec - Université Laval, Québec, Canada
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7
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Havlicek M, Uludağ K. A dynamical model of the laminar BOLD response. Neuroimage 2020; 204:116209. [DOI: 10.1016/j.neuroimage.2019.116209] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 08/11/2019] [Accepted: 09/17/2019] [Indexed: 12/18/2022] Open
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8
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Magnetic Resonance Imaging in Aneurysmal Subarachnoid Hemorrhage: Current Evidence and Future Directions. Neurocrit Care 2019; 29:241-252. [PMID: 29633155 DOI: 10.1007/s12028-018-0534-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Aneurysmal subarachnoid hemorrhage (aSAH) is associated with an unacceptably high mortality and chronic disability in survivors, underscoring a need to validate new approaches for treatment and prognosis. The use of advanced imaging, magnetic resonance imaging (MRI) in particular, could help address this gap given its versatile capacity to quantitatively evaluate and map changes in brain anatomy, physiology and functional activation. Yet there is uncertainty about the real value of brain MRI in the clinical setting of aSAH. METHODS In this review, we discuss current and emerging MRI research in aSAH. PubMed was searched from inception to June 2017, and additional studies were then chosen on the basis of relevance to the topics covered in this review. RESULTS Available studies suggest that brain MRI is a feasible, safe, and valuable testing modality. MRI detects brain abnormalities associated with neurologic examination, outcomes, and aneurysm treatment and thus has the potential to increase knowledge of aSAH pathophysiology as well as to guide management and outcome prediction. Newer pulse sequences have the potential to reveal structural and physiological changes that could also improve management of aSAH. CONCLUSION Research is needed to confirm the value of MRI-based biomarkers in clinical practice and as endpoints in clinical trials, with the goal of improving outcome for patients with aSAH.
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9
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Taylor AJ, Kim JH, Singh V, Halfen EJ, Pfeuffer J, Ress D. More than BOLD: Dual-spin populations create functional contrast. Magn Reson Med 2019; 83:681-694. [PMID: 31423634 DOI: 10.1002/mrm.27941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/16/2019] [Accepted: 07/21/2019] [Indexed: 11/06/2022]
Abstract
PURPOSE Functional MRI contrast has generally been associated with changes in transverse relaxivity caused by blood oxygen concentration, the so-called blood oxygen level dependent contrast. However, this interpretation of fMRI contrast has been called into question by several recent experiments at high spatial resolution. Experiments were conducted to examine contrast dependencies that cannot be explained only by differences in relaxivity in a single-spin population. METHODS Measurements of functional signal and contrast were obtained in human early visual cortex during a high-contrast visual stimulation over a large range of TEs and for several flip angles. Small voxels (1.5 mm) were used to restrict the measurements to cortical gray matter in early visual areas identified using retinotopic mapping procedures. RESULTS Measurements were consistent with models that include 2 spin populations. The dominant population has a relatively short transverse lifetime that is strongly modulated by activation. However, functional contrast is also affected by volume changes between this short-lived population and the longer-lived population. CONCLUSION Some of the previously observed "nonclassical" behaviors of functional contrast can be explained by these interacting dual-spin populations.
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Affiliation(s)
- Amanda J Taylor
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Jung H Kim
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | | | | | - Josef Pfeuffer
- Siemens Healthcare, Application Development, Erlangen, Germany
| | - David Ress
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
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10
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Advances in MR angiography with 7T MRI: From microvascular imaging to functional angiography. Neuroimage 2018; 168:269-278. [DOI: 10.1016/j.neuroimage.2017.01.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 01/03/2017] [Accepted: 01/09/2017] [Indexed: 01/15/2023] Open
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11
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Unschuld PG. Novel Translational Research Methodology and the Prospect to a Better Understanding of Neurodegenerative Disease. NEURODEGENER DIS 2018; 18:1-4. [PMID: 29339665 DOI: 10.1159/000486565] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Paul G Unschuld
- Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich, Zurich, Switzerland.,Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
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12
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Stout JN, Adalsteinsson E, Rosen BR, Bolar DS. Functional oxygen extraction fraction (OEF) imaging with turbo gradient spin echo QUIXOTIC (Turbo QUIXOTIC). Magn Reson Med 2017; 79:2713-2723. [PMID: 28984056 DOI: 10.1002/mrm.26947] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/14/2017] [Accepted: 09/06/2017] [Indexed: 11/12/2022]
Abstract
PURPOSE QUantitative Imaging of eXtraction of Oxygen and TIssue Consumption (QUIXOTIC) is a recent technique that measures voxel-wise oxygen extraction fraction (OEF) but suffers from long scan times, limiting its application. We implemented multiecho QUIXOTIC dubbed turbo QUIXOTIC (tQUIXOTIC) that reduces scan time eightfold and then applied it in functional MRI. METHODS tQUIXOTIC utilizes a novel turbo gradient spin echo readout enabling measurement of venular blood transverse relaxation rate in a single tag-control acquisition. Using tQUIXOTIC, we estimated cortical gray matter (GM) OEF, created voxel-by-voxel GM OEF maps, and quantified changes in visual cortex OEF during a blocked design flashing checkerboard visual stimulus. Contamination from cerebrospinal fluid partial volume averaging was estimated and corrected. RESULTS The average cortical GM OEF was estimated as 0.38 ± 0.06 (n = 8) using a 3.4-min acquisition. The average OEF in the visual cortex was estimated as 0.43 ± 0.04 at baseline and 0.35 ± 0.05 during activation, with an average %ΔOEF of -20%. These values are consistent with those of past studies. CONCLUSION tQUIXOTIC successfully estimated cortical GM OEF in clinical scan times and detected changes in OEF during blocked design visual stimulation. tQUIXOTIC will be useful to monitor regional OEF clinically and in blocked design or event-related functional MRI experiments. Magn Reson Med 79:2713-2723, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jeffrey N Stout
- Harvard-MIT Health Sciences and Technology, Institute of Medical Engineering & Science, MIT, Cambridge, Massachusetts, USA
| | - Elfar Adalsteinsson
- Harvard-MIT Health Sciences and Technology, Institute of Medical Engineering & Science, MIT, Cambridge, Massachusetts, USA.,Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Bruce R Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Massachusetts, USA.,Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Divya S Bolar
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Massachusetts, USA.,Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA
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13
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Havlicek M, Ivanov D, Poser BA, Uludag K. Echo-time dependence of the BOLD response transients – A window into brain functional physiology. Neuroimage 2017; 159:355-370. [DOI: 10.1016/j.neuroimage.2017.07.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 07/08/2017] [Accepted: 07/17/2017] [Indexed: 01/08/2023] Open
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14
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Techniques for blood volume fMRI with VASO: From low-resolution mapping towards sub-millimeter layer-dependent applications. Neuroimage 2016; 164:131-143. [PMID: 27867088 DOI: 10.1016/j.neuroimage.2016.11.039] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/24/2016] [Accepted: 11/14/2016] [Indexed: 12/24/2022] Open
Abstract
Quantitative cerebral blood volume (CBV) fMRI has the potential to overcome several specific limitations of BOLD fMRI. It provides direct physiological interpretability and promises superior localization specificity in applications of sub-millimeter resolution fMRI applications at ultra-high magnetic fields (7T and higher). Non-invasive CBV fMRI using VASO (vascular space occupancy), however, is inherently limited with respect to its data acquisition efficiency, restricting its imaging coverage and achievable spatial and temporal resolution. This limitation may be reduced with recent advanced acceleration and reconstruction strategies that allow two-dimensional acceleration, such as in simultaneous multi-slice (SMS) 2D-EPI or 3D-EPI in combination with CAIPIRINHA field-of-view shifting. In this study, we sought to determine the functional sensitivity and specificity of these readout strategies with VASO over a broad range of spatial resolutions; spanning from low spatial resolution (3mm) whole-cortex to sub-millimeter (0.75mm) slab-of-cortex (for cortical layer-dependent applications). In the thermal-noise-dominated regime of sub-millimeter resolutions, 3D-EPI-VASO provides higher temporal stability and sensitivity to detect changes in CBV compared to 2D-EPI-VASO. In this regime, 3D-EPI-VASO unveils task activation located in the cortical laminae with little contamination from surface veins, in contrast to the cortical surface weighting of GE-BOLD fMRI. In the physiological-noise-dominated regime of lower resolutions, however, 2D-SMS-VASO shows superior performance compared to 3D-EPI-VASO. Due to its superior sensitivity at a layer-dependent level, 3D-EPI VASO promises to play an important role in future neuroscientific applications of layer-dependent fMRI.
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15
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Donahue MJ, Juttukonda MR, Watchmaker JM. Noise concerns and post-processing procedures in cerebral blood flow (CBF) and cerebral blood volume (CBV) functional magnetic resonance imaging. Neuroimage 2016; 154:43-58. [PMID: 27622397 DOI: 10.1016/j.neuroimage.2016.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/22/2016] [Accepted: 09/03/2016] [Indexed: 01/19/2023] Open
Abstract
Functional neuroimaging with blood oxygenation level-dependent (BOLD) contrast has emerged as the most popular method for evaluating qualitative changes in brain function in humans. At typical human field strengths (1.5-3.0T), BOLD contrast provides a measure of changes in transverse water relaxation rates in and around capillary and venous blood, and as such provides only a surrogate marker of brain function that depends on dynamic changes in hemodynamics (e.g., cerebral blood flow and volume) and metabolism (e.g., oxygen extraction fraction and the cerebral metabolic rate of oxygen consumption). Alternative functional neuroimaging methods that are specifically sensitive to these constituents of the BOLD signal are being developed and applied in a growing number of clinical and neuroscience applications of quantitative cerebral physiology. These methods require additional considerations for interpreting and quantifying their contrast responsibly. Here, an overview of two popular methods, arterial spin labeling and vascular space occupancy, is presented specifically in the context of functional neuroimaging. Appropriate post-processing and experimental acquisition strategies are summarized with the motivation of reducing sensitivity to noise and unintended signal sources and improving quantitative accuracy of cerebral hemodynamics.
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Affiliation(s)
- Manus J Donahue
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA; Neurology, Vanderbilt University School of Medicine, Nashville, TN, USA; Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - Meher R Juttukonda
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jennifer M Watchmaker
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
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Multi-contrast T2(⁎)-relaxometry upon visual stimulation at 3T and 7T. Magn Reson Imaging 2016; 34:864-74. [PMID: 27046057 DOI: 10.1016/j.mri.2016.03.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/26/2016] [Indexed: 11/24/2022]
Abstract
This study aims to quantify the mean change of the effective transverse relaxation time T2(⁎) in active brain regions of human volunteers at field strengths of B0=3T and 7T. Besides the mono-exponential signal decay model an extended model is tested that considers mesoscopic field gradients across imaging voxels. Both models are checked for cross-talk and correlations between the parameters. A visual checkerboard-stimulation experiment with pause and stimulation periods of 50s and six repetitions was performed on healthy volunteers. Eleven contrasts were acquired in about 1.47s/1.43s at 3T/7T using a segmented multi-contrast echo-planar imaging (EPI) sequence. Average BOLD-signal time courses were calculated in a multi-step (non-)linear least-squares process. Baseline T2(⁎) values of 37.72ms/24.99ms (47.34ms/33.71ms) with stimulus-correlated changes ∆T2(⁎)of 1.32ms/0.74ms (1.99ms/1.43ms) resulted from the mono-exponential (extended) model for 3T/7T. A dependence of those values on the initial intensity S0 was observed. Stimulus-correlated changes of S0 in the order of 1% were measured at both field strengths. The mono-exponential model was found to be less prone to instabilities in the regression of both parameters. Signal alterations due to inflow were observed. Measured relaxation times agree with values from literature using repetitive stimulation. A strong dependence of the measured relaxation times on the inflow-related model parameter was found for both models. The extended model is applicable to dynamic neurofunctional measurements, but is currently limited due to the low number of contrasts acquired.
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