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Mardell LC, Spedden ME, O'Neill GC, Tierney TM, Timms RC, Zich C, Barnes GR, Bestmann S. Concurrent spinal and brain imaging with optically pumped magnetometers. J Neurosci Methods 2024; 406:110131. [PMID: 38583588 DOI: 10.1016/j.jneumeth.2024.110131] [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: 08/18/2023] [Revised: 03/11/2024] [Accepted: 04/03/2024] [Indexed: 04/09/2024]
Abstract
BACKGROUND The spinal cord and its interactions with the brain are fundamental for movement control and somatosensation. However, brain and spinal electrophysiology in humans have largely been treated as distinct enterprises, in part due to the relative inaccessibility of the spinal cord. Consequently, there is a dearth of knowledge on human spinal electrophysiology, including the multiple pathologies that affect the spinal cord as well as the brain. NEW METHOD Here we exploit recent advances in the development of wearable optically pumped magnetometers (OPMs) which can be flexibly arranged to provide coverage of both the spinal cord and the brain in relatively unconstrained environments. This system for magnetospinoencephalography (MSEG) measures both spinal and cortical signals simultaneously by employing custom-made scanning casts. RESULTS We evidence the utility of such a system by recording spinal and cortical evoked responses to median nerve stimulation at the wrist. MSEG revealed early (10 - 15 ms) and late (>20 ms) responses at the spinal cord, in addition to typical cortical evoked responses (i.e., N20). COMPARISON WITH EXISTING METHODS Early spinal evoked responses detected were in line with conventional somatosensory evoked potential recordings. CONCLUSION This MSEG system demonstrates the novel ability for concurrent non-invasive millisecond imaging of brain and spinal cord.
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Affiliation(s)
- Lydia C Mardell
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, WC1N 3BG, UK.
| | - Meaghan E Spedden
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - George C O'Neill
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - Tim M Tierney
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - Ryan C Timms
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - Catharina Zich
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, WC1N 3BG, UK
| | - Gareth R Barnes
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - Sven Bestmann
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, WC1N 3BG, UK; Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
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2
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Agyeman KA, Lee DJ, Russin J, Kreydin EI, Choi W, Abedi A, Lo YT, Cavaleri J, Wu K, Edgerton VR, Liu C, Christopoulos VN. Functional ultrasound imaging of the human spinal cord. Neuron 2024; 112:1710-1722.e3. [PMID: 38458198 DOI: 10.1016/j.neuron.2024.02.012] [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: 06/08/2023] [Revised: 11/03/2023] [Accepted: 02/15/2024] [Indexed: 03/10/2024]
Abstract
Utilizing the first in-human functional ultrasound imaging (fUSI) of the spinal cord, we demonstrate the integration of spinal functional responses to electrical stimulation. We record and characterize the hemodynamic responses of the spinal cord to a neuromodulatory intervention commonly used for treating pain and increasingly used for the restoration of sensorimotor and autonomic function. We found that the hemodynamic response to stimulation reflects a spatiotemporal modulation of the spinal cord circuitry not previously recognized. Our analytical capability offers a mechanism to assess blood flow changes with a new level of spatial and temporal precision in vivo and demonstrates that fUSI can decode the functional state of spinal networks in a single trial, which is of fundamental importance for developing real-time closed-loop neuromodulation systems. This work is a critical step toward developing a vital technique to study spinal cord function and effects of clinical neuromodulation.
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Affiliation(s)
- K A Agyeman
- Department of Bioengineering, University of California Riverside, Riverside, CA, USA
| | - D J Lee
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Rancho Los Amigos National Rehabilitation Center, Downey, CA, USA; Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - J Russin
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Rancho Los Amigos National Rehabilitation Center, Downey, CA, USA; Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - E I Kreydin
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Rancho Los Amigos National Rehabilitation Center, Downey, CA, USA; Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - W Choi
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - A Abedi
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Y T Lo
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Department of Neurosurgery, National Neuroscience Institute, Singapore, Singapore
| | - J Cavaleri
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - K Wu
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - V R Edgerton
- Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Rancho Los Amigos National Rehabilitation Center, Downey, CA, USA.
| | - C Liu
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Rancho Los Amigos National Rehabilitation Center, Downey, CA, USA; Institute of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
| | - V N Christopoulos
- Department of Bioengineering, University of California Riverside, Riverside, CA, USA; Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neurorestoration Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Neuroscience Graduate Program, University of California Riverside, Riverside, CA, USA.
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3
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Dabbagh A, Horn U, Kaptan M, Mildner T, Müller R, Lepsien J, Weiskopf N, Brooks JCW, Finsterbusch J, Eippert F. Reliability of task-based fMRI in the dorsal horn of the human spinal cord. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.22.572825. [PMID: 38187724 PMCID: PMC10769329 DOI: 10.1101/2023.12.22.572825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
The application of functional magnetic resonance imaging (fMRI) to the human spinal cord is still a relatively small field of research and faces many challenges. Here we aimed to probe the limitations of task-based spinal fMRI at 3T by investigating the reliability of spinal cord blood oxygen level dependent (BOLD) responses to repeated nociceptive stimulation across two consecutive days in 40 healthy volunteers. We assessed the test-retest reliability of subjective ratings, autonomic responses, and spinal cord BOLD responses to short heat pain stimuli (1s duration) using the intraclass correlation coefficient (ICC). At the group level, we observed robust autonomic responses as well as spatially specific spinal cord BOLD responses at the expected location, but no spatial overlap in BOLD response patterns across days. While autonomic indicators of pain processing showed good-to-excellent reliability, both β-estimates and z-scores of task-related BOLD responses showed poor reliability across days in the target region (gray matter of the ipsilateral dorsal horn). When taking into account the sensitivity of gradient-echo echo planar imaging (GE-EPI) to draining vein signals by including the venous plexus in the analysis, we observed BOLD responses with good reliability across days. Taken together, these results demonstrate that heat pain stimuli as short as one second are able to evoke a robust and spatially specific BOLD response, which is however strongly variable within participants across time, resulting in low reliability in the dorsal horn gray matter. Further improvements in data acquisition and analysis techniques are thus necessary before event-related spinal cord fMRI as used here can be reliably employed in longitudinal designs or clinical settings.
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Affiliation(s)
- Alice Dabbagh
- Max Planck Research Group Pain Perception, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Ulrike Horn
- Max Planck Research Group Pain Perception, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Merve Kaptan
- Max Planck Research Group Pain Perception, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, CA, USA
| | - Toralf Mildner
- Methods & Development Group Nuclear Magnetic Resonance, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Roland Müller
- Methods & Development Group Nuclear Magnetic Resonance, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Jöran Lepsien
- Methods & Development Group Nuclear Magnetic Resonance, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Nikolaus Weiskopf
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth Sciences, University of Leipzig, Leipzig, Germany
- Wellcome Centre for Human Neuroimaging, Institute of Neurology, University College London, London, UK
| | - Jonathan C W Brooks
- School of Psychology, University of East Anglia Wellcome Wolfson Brain Imaging Centre (UWWBIC), Norwich, United Kingdom
| | - Jürgen Finsterbusch
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Falk Eippert
- Max Planck Research Group Pain Perception, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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Kaptan M, Vannesjo SJ, Mildner T, Horn U, Hartley‐Davies R, Oliva V, Brooks JCW, Weiskopf N, Finsterbusch J, Eippert F. Automated slice-specific z-shimming for functional magnetic resonance imaging of the human spinal cord. Hum Brain Mapp 2022; 43:5389-5407. [PMID: 35938527 PMCID: PMC9704784 DOI: 10.1002/hbm.26018] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/21/2022] [Accepted: 06/24/2022] [Indexed: 01/15/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) of the human spinal cord faces many challenges, such as signal loss due to local magnetic field inhomogeneities. This issue can be addressed with slice-specific z-shimming, which compensates for the dephasing effect of the inhomogeneities using a slice-specific gradient pulse. Here, we aim to address outstanding issues regarding this technique by evaluating its effects on several aspects that are directly relevant for spinal fMRI and by developing two automated procedures in order to improve upon the time-consuming and subjective nature of manual selection of z-shims: one procedure finds the z-shim that maximizes signal intensity in each slice of an EPI reference-scan and the other finds the through-slice field inhomogeneity for each EPI-slice in field map data and calculates the required compensation gradient moment. We demonstrate that the beneficial effects of z-shimming are apparent across different echo times, hold true for both the dorsal and ventral horn, and are also apparent in the temporal signal-to-noise ratio (tSNR) of EPI time-series data. Both of our automated approaches were faster than the manual approach, lead to significant improvements in gray matter tSNR compared to no z-shimming and resulted in beneficial effects that were stable across time. While the field-map-based approach performed slightly worse than the manual approach, the EPI-based approach performed as well as the manual one and was furthermore validated on an external corticospinal data-set (N > 100). Together, automated z-shimming may improve the data quality of future spinal fMRI studies and lead to increased reproducibility in longitudinal studies.
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Affiliation(s)
- Merve Kaptan
- Max Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany
| | - S. Johanna Vannesjo
- Department of PhysicsNorwegian University of Science and TechnologyTrondheimNorway
| | - Toralf Mildner
- Max Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany
| | - Ulrike Horn
- Max Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany
| | | | - Valeria Oliva
- School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
| | - Jonathan C. W. Brooks
- School of PsychologyUniversity of East Anglia Wellcome Wolfson Brain Imaging Centre (UWWBIC)NorwichUK
| | - Nikolaus Weiskopf
- Max Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany,Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth SciencesLeipzig UniversityLeipzigGermany
| | - Jürgen Finsterbusch
- Department of Systems NeuroscienceUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Falk Eippert
- Max Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany
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5
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Tinnermann A, Sprenger C, Büchel C. Opioid analgesia alters corticospinal coupling along the descending pain system in healthy participants. eLife 2022; 11:74293. [PMID: 35471139 PMCID: PMC9042228 DOI: 10.7554/elife.74293] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 04/07/2022] [Indexed: 11/24/2022] Open
Abstract
Opioids are potent analgesic drugs with widespread cortical, subcortical, and spinal targets. In particular, the central pain system comprising ascending and descending pain pathways has high opioid receptor densities and is thus crucial for opioid analgesia. Here, we investigated the effects of the opioid remifentanil in a large sample (n = 78) of healthy male participants using combined corticospinal functional MRI. This approach offers the possibility to measure BOLD responses simultaneously in the brain and spinal cord, allowing us to investigate the role of corticospinal coupling in opioid analgesia. Our data show that opioids altered activity in regions involved in pain processing such as somatosensory regions, including the spinal cord and pain modulation such as prefrontal regions. Moreover, coupling strength along the descending pain system, that is, between the anterior cingulate cortex, periaqueductal gray, and spinal cord, was stronger in participants who reported stronger analgesia during opioid treatment while participants that received saline showed reduced coupling when experiencing less pain. These results indicate that coupling along the descending pain pathway is a potential mechanism of opioid analgesia and can differentiate between opioid analgesia and unspecific reductions in pain such as habituation.
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Affiliation(s)
- Alexandra Tinnermann
- Department for Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Max Planck School of Cognition, Leipzig, Germany
| | - Christian Sprenger
- Department for Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Büchel
- Department for Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Max Planck School of Cognition, Leipzig, Germany
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6
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Towards reliable spinal cord fMRI: assessment of common imaging protocols. Neuroimage 2022; 250:118964. [DOI: 10.1016/j.neuroimage.2022.118964] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/07/2022] [Accepted: 02/01/2022] [Indexed: 01/29/2023] Open
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7
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Martucci KT, Weber KA, Mackey SC. Spinal Cord Resting State Activity in Individuals With Fibromyalgia Who Take Opioids. Front Neurol 2021; 12:694271. [PMID: 34421798 PMCID: PMC8371264 DOI: 10.3389/fneur.2021.694271] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/28/2021] [Indexed: 11/24/2022] Open
Abstract
Chronic pain coincides with myriad functional alterations throughout the brain and spinal cord. While spinal cord mechanisms of chronic pain have been extensively characterized in animal models and in vitro, to date, research in patients with chronic pain has focused only very minimally on the spinal cord. Previously, spinal cord functional magnetic resonance imaging (fMRI) identified regional alterations in spinal cord activity in patients (who were not taking opioids) with fibromyalgia, a chronic pain condition. Here, in patients with fibromyalgia who take opioids (N = 15), we compared spinal cord resting-state fMRI data vs. patients with fibromyalgia not taking opioids (N = 15) and healthy controls (N = 14). We hypothesized that the opioid (vs. non-opioid) patient group would show greater regional alterations in spinal cord activity (i.e., the amplitude of low frequency fluctuations or ALFF, a measure of regional spinal cord activity). However, we found that regional spinal cord activity in the opioid group was more similar to healthy controls, while regional spinal cord activity in the non-opioid group showed more pronounced differences (i.e., ventral increases and dorsal decreases in regional ALFF) vs. healthy controls. Across patient groups, self-reported fatigue correlated with regional differences in spinal cord activity. Additionally, spinal cord functional connectivity and graph metrics did not differ among groups. Our findings suggest that, contrary to our main hypothesis, patients with fibromyalgia who take opioids do not have greater alterations in regional spinal cord activity. Thus, regional spinal cord activity may be less imbalanced in patients taking opioids compared to patients not taking opioids.
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Affiliation(s)
- Katherine T. Martucci
- Human Affect and Pain Neuroscience Laboratory, Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC, United States
| | - Kenneth A. Weber
- Systems Neuroscience and Pain Laboratory, Division of Pain Medicine, Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University, Palo Alto, CA, United States
| | - Sean C. Mackey
- Systems Neuroscience and Pain Laboratory, Division of Pain Medicine, Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University, Palo Alto, CA, United States
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8
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Barry RL, Conrad BN, Maki S, Watchmaker JM, McKeithan LJ, Box BA, Weinberg QR, Smith SA, Gore JC. Multi-shot acquisitions for stimulus-evoked spinal cord BOLD fMRI. Magn Reson Med 2020; 85:2016-2026. [PMID: 33169877 DOI: 10.1002/mrm.28570] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 10/02/2020] [Accepted: 10/05/2020] [Indexed: 12/23/2022]
Abstract
PURPOSE To demonstrate the feasibility of 3D multi-shot magnetic resonance imaging acquisitions for stimulus-evoked blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) in the human spinal cord in vivo. METHODS Two fMRI studies were performed at 3T. The first study was a hypercapnic gas challenge where data were acquired from healthy volunteers using a multi-shot 3D fast field echo (FFE) sequence as well as single-shot multi-slice echo-planar imaging (EPI). In the second study, another cohort of healthy volunteers performed an upper extremity motor task while fMRI data were acquired using a 3D multi-shot acquisition. RESULTS Both 2D-EPI and 3D-FFE were shown to be sensitive to BOLD signal changes in the cervical spinal cord, and had comparable contrast-to-noise ratios in gray matter. FFE exhibited much less signal drop-out and weaker geometric distortions compared to EPI. In the motor paradigm study, the mean number of active voxels was highest in the ventral gray matter horns ipsilateral to the side of the task and at the spinal level associated with innervation of finger extensors. CONCLUSIONS Highly multi-shot acquisition sequences such as 3D-FFE are well suited for stimulus-evoked spinal cord BOLD fMRI.
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Affiliation(s)
- Robert L Barry
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
- Harvard-Massachusetts Institute of Technology Health Sciences & Technology, Cambridge, MA, USA
| | - Benjamin N Conrad
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
- Neuroscience Graduate Program, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Satoshi Maki
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jennifer M Watchmaker
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lydia J McKeithan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Bailey A Box
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Quinn R Weinberg
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Seth A Smith
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
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9
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Kinany N, Pirondini E, Micera S, Van De Ville D. Dynamic Functional Connectivity of Resting-State Spinal Cord fMRI Reveals Fine-Grained Intrinsic Architecture. Neuron 2020; 108:424-435.e4. [PMID: 32910894 DOI: 10.1016/j.neuron.2020.07.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/23/2020] [Accepted: 07/18/2020] [Indexed: 12/24/2022]
Abstract
The neuroimaging community has shown tremendous interest in exploring the brain's spontaneous activity using functional magnetic resonance imaging (fMRI). On the contrary, the spinal cord has been largely overlooked despite its pivotal role in processing sensorimotor signals. Only a handful of studies have probed the organization of spinal resting-state fluctuations, always using static measures of connectivity. Many innovative approaches have emerged for analyzing dynamics of brain fMRI, but they have not yet been applied to the spinal cord, although they could help disentangle its functional architecture. Here, we leverage a dynamic connectivity method based on the clustering of hemodynamic-informed transients to unravel the rich dynamic organization of spinal resting-state signals. We test this approach in 19 healthy subjects, uncovering fine-grained spinal components and highlighting their neuroanatomical and physiological nature. We provide a versatile tool, the spinal innovation-driven co-activation patterns (SpiCiCAP) framework, to characterize spinal circuits during rest and task, as well as their disruption in neurological disorders.
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Affiliation(s)
- Nawal Kinany
- Medical Image Processing Laboratory, Center for Neuroprosthetics, Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland; Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics, Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland
| | - Elvira Pirondini
- Department of Radiology and Medical Informatics, University of Geneva, 1211 Geneva, Switzerland
| | - Silvestro Micera
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics, Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland; The BioRobotics Institute and Department of Excellence in Robotics and AI, Scuola Superiore Sant'Anna, 56025 Pontedera, Italy.
| | - Dimitri Van De Ville
- Medical Image Processing Laboratory, Center for Neuroprosthetics, Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland; Department of Radiology and Medical Informatics, University of Geneva, 1211 Geneva, Switzerland.
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10
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Mangini F, DiNuzzo M, Maugeri L, Moraschi M, Mascali D, Cedola A, Frezza F, Giove F, Fratini M. Numerical simulation of the blood oxygenation level-dependent functional magnetic resonance signal using finite element method. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3290. [PMID: 31808299 DOI: 10.1002/cnm.3290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 08/10/2019] [Accepted: 11/10/2019] [Indexed: 06/10/2023]
Abstract
Since the introduction of functional magnetic resonance imaging (fMRI), several computational approaches have been developed to examine the effect of the morphology and arrangement of blood vessels on the blood oxygenation-level dependent (BOLD) signal in the brain. In the present work, we implemented the original Ogawa's model using a numerical simulation based on the finite element method (FEM) instead of the analytical models. In literature, there are different works using analytical methods to analyse the transverse relaxation rate ( R2∗ ), which BOLD signal is related to, modelling the vascular system with simple and canonical geometries such as an infinite cylinder model (ICM) or a set of cylinders. We applied the numerical simulation to the extravascular BOLD signal as a function of angular vessel distribution (perpendicular vs parallel to the static magnetic field) relevant for anatomical districts characterized by geometrical symmetries, such as spinal cord. Numerical simulations confirmed analytical results for the canonical ICM. Moreover, the perturbation to the magnetic field induced by blood deoxyhaemoglobin, as quantified assuming Brownian diffusion of water molecules around the vessel, revealed that vessels contribute the most to the variation of the R2∗ when they are preferentially perpendicular to the external magnetic field, regardless of their size. Our results indicate that the numerical simulation method is sensitive to the effects of different vascular geometry. This work highlights the opportunity to extend R2∗ simulations to realistic models of vasculature based on high-resolution anatomical images.
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Affiliation(s)
- Fabio Mangini
- Fondazione Santa Lucia, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
| | - Mauro DiNuzzo
- Fondazione Santa Lucia, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
| | - Laura Maugeri
- Fondazione Santa Lucia, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
| | - Marta Moraschi
- Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Rome, Italy
| | - Daniele Mascali
- Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Rome, Italy
| | | | - Fabrizio Frezza
- Department of Information Engineering, Electronics and Telecommunications, La Sapienza University of Rome, Rome, Italy
| | - Federico Giove
- Fondazione Santa Lucia, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
- Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Rome, Italy
| | - Michela Fratini
- Fondazione Santa Lucia, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
- CNR Consiglio Nazionale delle Ricerche, Rome, Italy
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11
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Kinany N, Pirondini E, Martuzzi R, Mattera L, Micera S, Van de Ville D. Functional imaging of rostrocaudal spinal activity during upper limb motor tasks. Neuroimage 2019; 200:590-600. [DOI: 10.1016/j.neuroimage.2019.05.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 05/12/2019] [Accepted: 05/13/2019] [Indexed: 11/25/2022] Open
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Conrad BN, Barry RL, Rogers BP, Maki S, Mishra A, Thukral S, Sriram S, Bhatia A, Pawate S, Gore JC, Smith SA. Multiple sclerosis lesions affect intrinsic functional connectivity of the spinal cord. Brain 2019; 141:1650-1664. [PMID: 29648581 DOI: 10.1093/brain/awy083] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/04/2018] [Indexed: 11/13/2022] Open
Abstract
Patients with multiple sclerosis present with focal lesions throughout the spinal cord. There is a clinical need for non-invasive measurements of spinal cord activity and functional organization in multiple sclerosis, given the cord's critical role in the disease. Recent reports of spontaneous blood oxygenation level-dependent fluctuations in the spinal cord using functional MRI suggest that, like the brain, cord activity at rest is organized into distinct, synchronized functional networks among grey matter regions, likely related to motor and sensory systems. Previous studies looking at stimulus-evoked activity in the spinal cord of patients with multiple sclerosis have demonstrated increased levels of activation as well as a more bilateral distribution of activity compared to controls. Functional connectivity studies of brain networks in multiple sclerosis have revealed widespread alterations, which may take on a dynamic trajectory over the course of the disease, with compensatory increases in connectivity followed by decreases associated with structural damage. We build upon this literature by examining functional connectivity in the spinal cord of patients with multiple sclerosis. Using ultra-high field 7 T imaging along with processing strategies for robust spinal cord functional MRI and lesion identification, the present study assessed functional connectivity within cervical cord grey matter of patients with relapsing-remitting multiple sclerosis (n = 22) compared to a large sample of healthy controls (n = 56). Patient anatomical images were rated for lesions by three independent raters, with consensus ratings revealing 19 of 22 patients presented with lesions somewhere in the imaged volume. Linear mixed models were used to assess effects of lesion location on functional connectivity. Analysis in control subjects demonstrated a robust pattern of connectivity among ventral grey matter regions as well as a distinct network among dorsal regions. A gender effect was also observed in controls whereby females demonstrated higher ventral network connectivity. Wilcoxon rank-sum tests detected no differences in average connectivity or power of low frequency fluctuations in patients compared to controls. The presence of lesions was, however, associated with local alterations in connectivity with differential effects depending on columnar location. The patient results suggest that spinal cord functional networks are generally intact in relapsing-remitting multiple sclerosis but that lesions are associated with focal abnormalities in intrinsic connectivity. These findings are discussed in light of the current literature on spinal cord functional MRI and the potential neurological underpinnings.
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Affiliation(s)
- Benjamin N Conrad
- Neuroscience Graduate Program, Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Robert L Barry
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Baxter P Rogers
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Satoshi Maki
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Arabinda Mishra
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Saakshi Thukral
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Subramaniam Sriram
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Aashim Bhatia
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Siddharama Pawate
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - John C Gore
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Seth A Smith
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
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13
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Effect of myocardial ischemic preconditioning on ischemia-reperfusion stimulation-induced activation in rat thoracic spinal cord with functional MRI. Int J Cardiol 2019; 285:59-64. [PMID: 30905517 DOI: 10.1016/j.ijcard.2019.03.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 03/06/2019] [Accepted: 03/13/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND Myocardial ischemia and reperfusion-evoked spinal reflexes involve nociceptive signals that trigger neuronal excitation through cardiac afferents, projecting into the thoracic spinal cord. Ischemic preconditioning (IPC) involves brief episodes of sublethal ischemia and reperfusion enhances the resistance of the myocardium to subsequent ischemic insults. This study investigated the effects of IPC on ischemia-reperfusion (I/R) stimulation-induced activation in the thoracic spinal cord of rats. METHODS A new remotely controlled I/R model was established. The infarct size was determined as a percentage of area at risk (IS/AAR) and arrhythmia scores were evaluated. Non-invasive in vivo fMRI was used for signal quantitative analysis of thoracic spinal spatiotemporal. The role of IPC on the excitability of substantia gelatinosa (SG) neurons was assessed by spinal patch clamp recording technique. The altered expressions of c-Fos, SP, and CGRP in T4 segment were detected by immunohistochemical staining. RESULTS The novel I/R model was induced successfully and reliably utilized, and IPC treatment markedly reduced the myocardial infarct size. fMRI analysis revealed that IPC reduced the increased BOLD signals induced by prolonged ischemia-reperfusion. Patch clamp recording showed that IPC treatment reversed the enhanced excitability of SG neurons during I/R treatment. The results of immunofluorescent staining indicated that IPC mitigated the I/R-induced dramatic increase of c-Fos, and reduced the release of SP and CGRP in dorsal horns of spinal cord. CONCLUSIONS These results suggested that IPC suppressed neuronal activation induced by I/R stimuli in rat thoracic spinal cord using spinal cord fMRI and patch clamp recording techniques.
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Martucci KT, Weber KA, Mackey SC. Altered Cervical Spinal Cord Resting-State Activity in Fibromyalgia. Arthritis Rheumatol 2019; 71:441-450. [PMID: 30281205 DOI: 10.1002/art.40746] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 09/27/2018] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Altered afferent input and central neural modulation are thought to contribute to fibromyalgia symptoms, and these processes converge within the spinal cord. We undertook this study to investigate the hypothesis that, using resting-state functional magnetic resonance imaging (rs-fMRI) of the cervical spinal cord, we would observe altered frequency-dependent activity in fibromyalgia. METHODS Cervical spinal cord rs-fMRI was conducted in fibromyalgia patients (n = 16) and healthy controls (n = 17). We analyzed the amplitude of low-frequency fluctuations (ALFF), a measure of low-frequency oscillatory power, for frequencies of 0.01-0.198 Hz and frequency sub-bands to determine regional and frequency-specific alterations in fibromyalgia. Functional connectivity and graph metrics were also analyzed. RESULTS As compared to healthy controls (n = 14), greater ventral and lesser dorsal mean ALFF of the cervical spinal cord was observed in fibromyalgia patients ( n = 15) (uncorrected P < 0.05) for frequencies of 0.01-0.198 Hz and all sub-bands. Additionally, lesser mean ALFF within the right dorsal quadrant (corrected P < 0.05) for frequencies of 0.01-0.198 Hz and sub-band frequencies of 0.073-0.198 Hz was observed in fibromyalgia. Regional mean ALFF was not correlated with pain; however, regional lesser mean ALFF was correlated with fatigue in patients (r = 0.763, P = 0.001). Functional connectivity and graph metrics were similar between groups. CONCLUSION Our results indicate unbalanced activity between the ventral and dorsal cervical spinal cord in fibromyalgia. Increased ventral neural processes and decreased dorsal neural processes may reflect the presence of central sensitization and contribute to fatigue and other bodily symptoms in fibromyalgia.
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Affiliation(s)
- Katherine T Martucci
- Stanford University, Stanford, California, and Duke University, Durham, North Carolina
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15
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Hu Y, Jin R, Li G, Luk KDK, Wu EX. Robust spinal cord resting-state fMRI using independent component analysis-based nuisance regression noise reduction. J Magn Reson Imaging 2018; 48:1421-1431. [DOI: 10.1002/jmri.26048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 03/23/2018] [Indexed: 11/11/2022] Open
Affiliation(s)
- Yong Hu
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine; The University of Hong Kong; Pokfulam Hong Kong
| | - Richu Jin
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine; The University of Hong Kong; Pokfulam Hong Kong
| | - Guangsheng Li
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine; The University of Hong Kong; Pokfulam Hong Kong
- Department of Orthopaedics; Affiliated Hospital of Guangdong Medical University; Zhanjiang China
| | - Keith DK Luk
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine; The University of Hong Kong; Pokfulam Hong Kong
| | - Ed. X. Wu
- Department of Electrical and Electronic Engineering, Faculty of Engineering; University of Hong Kong; Pokfulam Hong Kong
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16
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Tinnermann A, Geuter S, Sprenger C, Finsterbusch J, Büchel C. Interactions between brain and spinal cord mediate value effects in nocebo hyperalgesia. Science 2018; 358:105-108. [PMID: 28983051 DOI: 10.1126/science.aan1221] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 08/22/2017] [Indexed: 11/02/2022]
Abstract
Value information about a drug, such as the price tag, can strongly affect its therapeutic effect. We discovered that value information influences adverse treatment outcomes in humans even in the absence of an active substance. Labeling an inert treatment as expensive medication led to stronger nocebo hyperalgesia than labeling it as cheap medication. This effect was mediated by neural interactions between cortex, brainstem, and spinal cord. In particular, activity in the prefrontal cortex mediated the effect of value on nocebo hyperalgesia. Value furthermore modulated coupling between prefrontal areas, brainstem, and spinal cord, which might represent a flexible mechanism through which higher-cognitive representations, such as value, can modulate early pain processing.
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Affiliation(s)
- A Tinnermann
- Institute of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - S Geuter
- Institute of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.,Institute of Cognitive Science, University of Colorado-Boulder, Boulder, CO 80309, USA
| | - C Sprenger
- Institute of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.,Computational and Biological Learning Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
| | - J Finsterbusch
- Institute of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - C Büchel
- Institute of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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17
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Weber KA, Sentis AI, Bernadel-Huey ON, Chen Y, Wang X, Parrish TB, Mackey S. Thermal Stimulation Alters Cervical Spinal Cord Functional Connectivity in Humans. Neuroscience 2017; 369:40-50. [PMID: 29101078 DOI: 10.1016/j.neuroscience.2017.10.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/23/2017] [Accepted: 10/24/2017] [Indexed: 11/28/2022]
Abstract
The spinal cord has an active role in the modulation and transmission of the neural signals traveling between the body and the brain. Recent advancements in functional magnetic resonance imaging (fMRI) have made the in vivo examination of spinal cord function in humans now possible. This technology has been recently extended to the investigation of resting state functional networks in the spinal cord, leading to the identification of distinct patterns of spinal cord functional connectivity. In this study, we expand on the previous work and further investigate resting state cervical spinal cord functional connectivity in healthy participants (n = 15) using high resolution imaging coupled with both seed-based functional connectivity analyses and graph theory-based metrics. Within spinal cord segment functional connectivity was present between the left and right ventral horns (bilateral motor network), left and right dorsal horns (bilateral sensory network), and the ipsilateral ventral and dorsal horns (unilateral sensory-motor network). Functional connectivity between the spinal cord segments was less apparent with the connectivity centered at the region of interest and spanning <20 mm along the superior-inferior axis. In a subset of participants (n = 10), the cervical spinal cord functional network was demonstrated to be state-dependent as thermal stimulation of the right ventrolateral forearm resulted in significant disruption of the bilateral sensory network, increased network global efficiency, and decreased network modularity.
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Affiliation(s)
- Kenneth A Weber
- Systems Neuroscience and Pain Lab, Department of Anesthesia, Perioperative and Pain Medicine, Stanford University, Palo Alto 94304, CA, USA.
| | - Amy I Sentis
- Systems Neuroscience and Pain Lab, Department of Anesthesia, Perioperative and Pain Medicine, Stanford University, Palo Alto 94304, CA, USA
| | - Olivia N Bernadel-Huey
- Systems Neuroscience and Pain Lab, Department of Anesthesia, Perioperative and Pain Medicine, Stanford University, Palo Alto 94304, CA, USA
| | - Yufen Chen
- Department of Radiology, Northwestern University, Chicago, IL 60611, USA
| | - Xue Wang
- Department of Radiology, Northwestern University, Chicago, IL 60611, USA
| | - Todd B Parrish
- Department of Radiology, Northwestern University, Chicago, IL 60611, USA
| | - Sean Mackey
- Systems Neuroscience and Pain Lab, Department of Anesthesia, Perioperative and Pain Medicine, Stanford University, Palo Alto 94304, CA, USA
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18
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Harita S, Stroman PW. Confirmation of resting-state BOLD fluctuations in the human brainstem and spinal cord after identification and removal of physiological noise. Magn Reson Med 2017; 78:2149-2156. [DOI: 10.1002/mrm.26606] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 12/20/2016] [Accepted: 12/20/2016] [Indexed: 02/02/2023]
Affiliation(s)
- Shreyas Harita
- Centre for Neuroscience Studies; Queen's University; Kingston Canada
| | - Patrick W. Stroman
- Centre for Neuroscience Studies; Queen's University; Kingston Canada
- Department of Biomedical and Molecular Sciences; Queen's University; Kingston Canada
- Department of Physics; Queen's University; Kingston Canada
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19
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Eippert F, Kong Y, Winkler AM, Andersson JL, Finsterbusch J, Büchel C, Brooks JCW, Tracey I. Investigating resting-state functional connectivity in the cervical spinal cord at 3T. Neuroimage 2016; 147:589-601. [PMID: 28027960 PMCID: PMC5315056 DOI: 10.1016/j.neuroimage.2016.12.072] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/20/2016] [Accepted: 12/23/2016] [Indexed: 12/12/2022] Open
Abstract
The study of spontaneous fluctuations in the blood-oxygen-level-dependent (BOLD) signal has recently been extended from the brain to the spinal cord. Two ultra-high field functional magnetic resonance imaging (fMRI) studies in humans have provided evidence for reproducible resting-state connectivity between the dorsal horns as well as between the ventral horns, and a study in non-human primates has shown that these resting-state signals are impacted by spinal cord injury. As these studies were carried out at ultra-high field strengths using region-of-interest (ROI) based analyses, we investigated whether such resting-state signals could also be observed at the clinically more prevalent field strength of 3 T. In a reanalysis of a sample of 20 healthy human participants who underwent a resting-state fMRI acquisition of the cervical spinal cord, we were able to observe significant dorsal horn connectivity as well as ventral horn connectivity, but no consistent effects for connectivity between dorsal and ventral horns, thus replicating the human 7 T results. These effects were not only observable when averaging along the acquired length of the spinal cord, but also when we examined each of the acquired spinal segments separately, which showed similar patterns of connectivity. Finally, we investigated the robustness of these resting-state signals against variations in the analysis pipeline by varying the type of ROI creation, temporal filtering, nuisance regression and connectivity metric. We observed that – apart from the effects of band-pass filtering – ventral horn connectivity showed excellent robustness, whereas dorsal horn connectivity showed moderate robustness. Together, our results provide evidence that spinal cord resting-state connectivity is a robust and spatially consistent phenomenon that could be a valuable tool for investigating the effects of pathology, disease progression, and treatment response in neurological conditions with a spinal component, such as spinal cord injury.
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Affiliation(s)
- Falk Eippert
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
| | - Yazhuo Kong
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Magnetic Resonance Imaging Research Centre, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
| | - Anderson M Winkler
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Jesper L Andersson
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Jürgen Finsterbusch
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Büchel
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Irene Tracey
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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20
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Liu X, Qian W, Jin R, Li X, Luk KDK, Wu EX, Hu Y. Amplitude of Low Frequency Fluctuation (ALFF) in the Cervical Spinal Cord with Stenosis: A Resting State fMRI Study. PLoS One 2016; 11:e0167279. [PMID: 27907060 PMCID: PMC5132295 DOI: 10.1371/journal.pone.0167279] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/09/2016] [Indexed: 12/14/2022] Open
Abstract
Cervical spondylotic myelopathy (CSM) is a common spinal cord dysfunction disease with complex symptoms in clinical presentation. Resting state fMRI (rsfMRI) has been introduced to study the mechanism of neural development of CSM. However, most of those studies focused on intrinsic functional connectivity rather than intrinsic regional neural activity level which is also frequently analyzed in rsfMRI studies. Thus, this study aims to explore whether the level of neural activity changes on the myelopathic cervical cord and evaluate the possible relationship between this change and clinical symptoms through amplitude of low frequency fluctuation (ALFF). Eighteen CSM patients and twenty five healthy subjects participated in rsfMRI scanning. ALFF was investigated on each patient and subject. The results suggested that ALFF values were higher in the CSM patients at all cervical segments, compared to the healthy controls. The severity of myelopathy was associated with the increase of ALFF. This finding would enrich our understanding on the neural development mechanism of CSM.
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Affiliation(s)
- Xiaojia Liu
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
- Department of Electrical and Electronic Engineering, Faculty of Engineering, The University of Hong Kong, Pokfulam, Hong Kong
| | - Wenshu Qian
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Richu Jin
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Xiang Li
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Keith DK Luk
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Ed. X. Wu
- Department of Electrical and Electronic Engineering, Faculty of Engineering, The University of Hong Kong, Pokfulam, Hong Kong
| | - Yong Hu
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
- Spinal division, Department of Orthopaedics, Affiliated Hospital of Guangdong Medical University, Guangdong, China
- * E-mail:
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21
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Eippert F, Kong Y, Jenkinson M, Tracey I, Brooks JCW. Denoising spinal cord fMRI data: Approaches to acquisition and analysis. Neuroimage 2016; 154:255-266. [PMID: 27693613 DOI: 10.1016/j.neuroimage.2016.09.065] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/23/2016] [Accepted: 09/27/2016] [Indexed: 01/11/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) of the human spinal cord is a difficult endeavour due to the cord's small cross-sectional diameter, signal drop-out as well as image distortion due to magnetic field inhomogeneity, and the confounding influence of physiological noise from cardiac and respiratory sources. Nevertheless, there is great interest in spinal fMRI due to the spinal cord's role as the principal sensorimotor interface between the brain and the body and its involvement in a variety of sensory and motor pathologies. In this review, we give an overview of the various methods that have been used to address the technical challenges in spinal fMRI, with a focus on reducing the impact of physiological noise. We start out by describing acquisition methods that have been tailored to the special needs of spinal fMRI and aim to increase the signal-to-noise ratio and reduce distortion in obtained images. Following this, we concentrate on image processing and analysis approaches that address the detrimental effects of noise. While these include variations of standard pre-processing methods such as motion correction and spatial filtering, the main focus lies on denoising techniques that can be applied to task-based as well as resting-state data sets. We review both model-based approaches that rely on externally acquired respiratory and cardiac signals as well as data-driven approaches that estimate and correct for noise using the data themselves. We conclude with an outlook on techniques that have been successfully applied for noise reduction in brain imaging and whose use might be beneficial for fMRI of the human spinal cord.
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Affiliation(s)
- Falk Eippert
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Yazhuo Kong
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Mark Jenkinson
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Irene Tracey
- Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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22
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Organization of the intrinsic functional network in the cervical spinal cord: A resting state functional MRI study. Neuroscience 2016; 336:30-38. [PMID: 27590264 DOI: 10.1016/j.neuroscience.2016.08.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 08/22/2016] [Accepted: 08/24/2016] [Indexed: 12/29/2022]
Abstract
Resting state functional magnetic resonance imaging (rsfMRI) has been extensively applied to investigate the organization of functional networks in the brain. As an essential part of the central nervous system (CNS), the spinal cord has not been well explored about its intrinsic functional network. In this study, we aim to thoroughly investigate the characteristics of the intrinsic functional network in the spinal cord using rsfMRI. Functional connectivity and graph theory analysis were employed to evaluate the organization of the functional network, including its topology and network communication properties. Furthermore, the reproducibility of rsfMRI analysis on the spinal cord was also examined by intra-class correlation (ICC). Comprehensive evaluation of the intrinsic functional organization presented a non-uniform distribution of topological characteristics of the functional network, in which the upper levels (C2 and C3 vertebral levels) of the cervical spinal cord showed high levels of connectivity. The present results revealed the significance of the upper cervical cord in the intrinsic functional network of the human cervical spinal cord. In addition, this study demonstrated the efficiency of the cervical spinal cord functional network and the reproducibility of rsfMRI analysis on the spinal cord was also confirmed. As knowledge expansion of intrinsic functional network from the brain to the spinal cord, this study shed light on the organization of the spinal cord functional network in both normal development and clinical disorders.
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23
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Spinal cord-midbrain functional connectivity is related to perceived pain intensity: a combined spino-cortical FMRI study. J Neurosci 2015; 35:4248-57. [PMID: 25762671 DOI: 10.1523/jneurosci.4897-14.2015] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The dynamic interaction between ascending spinocortical nociceptive signaling and the descending control of the dorsal horn (DH) by brain regions such as the periaqueductal gray matter (PAG) plays a critical role in acute and chronic pain. To noninvasively investigate the processing of nociceptive stimuli in humans, previous fMRI studies either focused exclusively on the brain or, more recently, on the spinal cord. However, to relate neuronal responses in the brain to responses in the spinal cord and to assess the functional interplay between both sites in normal and aberrant conditions, fMRI of both regions within one experiment is necessary. Employing a new MRI acquisition protocol with two separate slice stacks, individually adapted resolutions and parameter settings that are dynamically updated to the optimized settings for the respective region we assessed neuronal activity in the spinal cord and in the brain within one measurement at 3 T. Using a parametric pain paradigm with thermal stimulation to the left radial forearm, we observed BOLD responses in the ipsilateral DH of the spinal segment C6 and corresponding neuronal responses in typical pain-processing brain regions. Based on correlations of adjusted time series, we are able to reveal functional connectivity between the spinal C6-DH and the thalamus, primary somatosensory cortex, bilateral insula, bilateral striatum, and key structures of the descending pain-modulatory system such as the PAG, the hypothalamus, and the amygdala. Importantly, the individual strength of the spinal-PAG coupling predicted individual pain ratings highlighting the functional relevance of this system during physiological pain signaling.
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24
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van de Sand MF, Sprenger C, Büchel C. BOLD responses to itch in the human spinal cord. Neuroimage 2015; 108:138-43. [DOI: 10.1016/j.neuroimage.2014.12.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/10/2014] [Accepted: 12/05/2014] [Indexed: 12/16/2022] Open
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25
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Intrinsically organized resting state networks in the human spinal cord. Proc Natl Acad Sci U S A 2014; 111:18067-72. [PMID: 25472845 DOI: 10.1073/pnas.1414293111] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Spontaneous fluctuations in functional magnetic resonance imaging (fMRI) signals of the brain have repeatedly been observed when no task or external stimulation is present. These fluctuations likely reflect baseline neuronal activity of the brain and correspond to functionally relevant resting-state networks (RSN). It is not known however, whether intrinsically organized and spatially circumscribed RSNs also exist in the spinal cord, the brain's principal sensorimotor interface with the body. Here, we use recent advances in spinal fMRI methodology and independent component analysis to answer this question in healthy human volunteers. We identified spatially distinct RSNs in the human spinal cord that were clearly separated into dorsal and ventral components, mirroring the functional neuroanatomy of the spinal cord and likely reflecting sensory and motor processing. Interestingly, dorsal (sensory) RSNs were separated into right and left components, presumably related to ongoing hemibody processing of somatosensory information, whereas ventral (motor) RSNs were bilateral, possibly related to commissural interneuronal networks involved in central pattern generation. Importantly, all of these RSNs showed a restricted spatial extent along the spinal cord and likely conform to the spinal cord's functionally relevant segmental organization. Although the spatial and temporal properties of the dorsal and ventral RSNs were found to be significantly different, these networks showed significant interactions with each other at the segmental level. Together, our data demonstrate that intrinsically highly organized resting-state fluctuations exist in the human spinal cord and are thus a hallmark of the entire central nervous system.
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26
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Yang X, Kang H, Newton AT, Landman BA. Evaluation of statistical inference on empirical resting state fMRI. IEEE Trans Biomed Eng 2014; 61:1091-9. [PMID: 24658234 DOI: 10.1109/tbme.2013.2294013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Modern statistical inference techniques may be able to improve the sensitivity and specificity of resting state functional magnetic resonance imaging (rs-fMRI) connectivity analysis through more realistic assumptions. In simulation, the advantages of such methods are readily demonstrable. However, quantitative empirical validation remains elusive in vivo as the true connectivity patterns are unknown and noise distributions are challenging to characterize, especially in ultra-high field (e.g., 7T fMRI). Though the physiological characteristics of the fMRI signal are difficult to replicate in controlled phantom studies, it is critical that the performance of statistical techniques be evaluated. The SIMulation EXtrapolation (SIMEX) method has enabled estimation of bias with asymptotically consistent estimators on empirical finite sample data by adding simulated noise . To avoid the requirement of accurate estimation of noise structure, the proposed quantitative evaluation approach leverages the theoretical core of SIMEX to study the properties of inference methods in the face of diminishing data (in contrast to increasing noise). The performance of ordinary and robust inference methods in simulation and empirical rs-fMRI are compared using the proposed quantitative evaluation approach. This study provides a simple, but powerful method for comparing a proxy for inference accuracy using empirical data.
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Abstract
Functional magnetic resonance imaging using blood oxygenation level dependent (BOLD) contrast is well established as one of the most powerful methods for mapping human brain function. Numerous studies have measured how low-frequency BOLD signal fluctuations from the brain are correlated between voxels in a resting state, and have exploited these signals to infer functional connectivity within specific neural circuits. However, to date there have been no previous substantiated reports of resting state correlations in the spinal cord. In a cohort of healthy volunteers, we observed robust functional connectivity between left and right ventral (motor) horns, and between left and right dorsal (sensory) horns. Our results demonstrate that low-frequency BOLD fluctuations are inherent in the spinal cord as well as the brain, and by analogy to cortical circuits, we hypothesize that these correlations may offer insight into the execution and maintenance of sensory and motor functions both locally and within the cerebrum. DOI:http://dx.doi.org/10.7554/eLife.02812.001 Brain imaging methods such as functional magnetic resonance imaging (fMRI) can provide us with a picture of what the brain is doing when a person is carrying out a specific task. For example, an fMRI scan recorded whilst someone is reading is likely to show activity in regions in the left hemisphere of the brain that are known to be involved in language comprehension. fMRI can also be used to measure patterns of neuronal activity when someone is awake but not engaged in a specific task. This approach, known as resting state fMRI, can be used to examine which regions of the resting brain are active at the same time. Researchers are interested in these patterns of brain activity because they reflect neural circuits that work together to produce different functions and behaviors. Over 4000 papers have used resting state fMRI to study the human brain. However, to date there has been no conclusive investigation of resting state activity in the spinal cord. This is largely because the spinal cord is much smaller than the brain, and most fMRI scanners are not sensitive enough to study it in detail. Consequently, little is known about intrinsic neural circuits in the resting spinal cord. Now Barry et al. have used advances in fMRI technology to show that resting state functional connectivity does indeed exist in the spinal cord. Correlations were found in the resting levels of activity between spatially distinct areas of the cord, specifically between the ventral horns and between the dorsal horns. The ventral horns relay motor signals to the body, whilst the dorsal horns receive sensory signals from the body. These findings also have clinical applications. Some patients with incomplete spinal cord injuries can recover near normal function, but the mechanisms responsible for this recovery are unclear because clinicians have not been able to probe neuronal connections in the spinal cord in a non-invasive manner. The work of Barry et al. should help with efforts to understand the neuronal changes that support recovery from spinal cord injury. DOI:http://dx.doi.org/10.7554/eLife.02812.002
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Affiliation(s)
- Robert L Barry
- Vanderbilt University Institute of Imaging Science, Nashville, United States Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, United States
| | - Seth A Smith
- Vanderbilt University Institute of Imaging Science, Nashville, United States Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, United States Department of Biomedical Engineering, Vanderbilt University, Nashville, United States
| | - Adrienne N Dula
- Vanderbilt University Institute of Imaging Science, Nashville, United States Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, United States
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Nashville, United States Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, United States Department of Biomedical Engineering, Vanderbilt University, Nashville, United States
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28
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Middleton DM, Mohamed FB, Barakat N, Hunter LN, Shellikeri S, Finsterbusch J, Faro SH, Shah P, Samdani AF, Mulcahey M. An investigation of motion correction algorithms for pediatric spinal cord DTI in healthy subjects and patients with spinal cord injury. Magn Reson Imaging 2014; 32:433-9. [DOI: 10.1016/j.mri.2014.01.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 01/25/2014] [Accepted: 01/27/2014] [Indexed: 11/27/2022]
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29
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Fratini M, Moraschi M, Maraviglia B, Giove F. On the impact of physiological noise in spinal cord functional MRI. J Magn Reson Imaging 2013; 40:770-7. [PMID: 24925698 DOI: 10.1002/jmri.24467] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 09/11/2013] [Indexed: 01/09/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) techniques are widely exploited for the study of brain activation. In recent years, similar approaches have been attempted for the study of spinal cord function; however, obtaining good functional images of spinal cord still represents a technical and scientific challenge. Some of the main limiting factors can be classified under the broad category of "physiological noise," and are related to 1) the cerebrospinal fluid (CSF) flux in the subarachnoid space surrounding the spinal cord; 2) the cord motion itself; and 3) the small area of the cord, which makes it critical to have a high image resolution. In addition, the different magnetic susceptibility properties of tissues surrounding the spinal cord reduce the local homogeneity of the static magnetic field, causing image distortion, reduction of the effective resolution, and signal loss, all effects that are modulated by motion. For these reasons, a number of methods have been developed for the purpose of denoising spinal cord fMRI time series. In this work, after a short introduction on the relevant features of the spinal cord anatomy, we review the main sources of physiological noise in spinal cord fMRI and discuss the main approaches useful for its mitigation.
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Affiliation(s)
- Michela Fratini
- MARBILab - Museo storico della fisica e Centro di studi e ricerche Enrico Fermi, Roma, Italy; Dipartimento di Fisica, Sapienza Universita' di Roma, Roma, Italy
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30
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Finsterbusch J, Sprenger C, Büchel C. Combined T2*-weighted measurements of the human brain and cervical spinal cord with a dynamic shim update. Neuroimage 2013; 79:153-61. [PMID: 23603283 DOI: 10.1016/j.neuroimage.2013.04.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 02/21/2013] [Accepted: 04/04/2013] [Indexed: 10/26/2022] Open
Abstract
Important functions of the central nervous system such as sensory processing and motor execution, involve the spinal cord. Recent advances in human functional MRI have allowed to investigate spinal cord neuronal processes using the blood-oxygenation-level-dependent (BOLD) contrast. However, to assess the functional connectivity between the brain and the spinal cord, functional MRI measurements covering both regions in the same experiment are required. Unfortunately, the ideal MRI setup differs considerably for the brain and the spinal cord with respect to resolution, field-of-view, relevant receive coils, and, in particular, shim adjustments required to minimize distortion artifacts. Here, these issues are addressed for combined T2*-weighted MRI measurements of the human brain and the cervical spinal cord by using adapted parameter settings (field-of-view, in-plane resolution, slice thickness, and receiver bandwidth) for each region, a dynamic receive coil element selection where for each slice only the elements with significant signal contributions are considered, and, most importantly, the implementation of a dynamic update of the frequency and the linear shims in order to provide shim settings individually adapted to the brain and spinal cord subvolume. The feasibility of this setup for combined measurements is demonstrated in healthy volunteers at 3T. Although geometric distortions are slightly more pronounced and the temporal signal-to-noise ratio is lower as compared to measurements focusing to the brain or spinal cord only, the overall image quality can be expected to be sufficient for combined functional MRI experiments. Thus, the presented approach could help to unravel the functional coupling between the brain and the spinal cord.
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Affiliation(s)
- Jürgen Finsterbusch
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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31
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Changes in the spinal segmental motor output for stepping during development from infant to adult. J Neurosci 2013; 33:3025-36a. [PMID: 23407959 DOI: 10.1523/jneurosci.2722-12.2013] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Human stepping movements emerge in utero and show several milestones during development to independent walking. Recently, imaging has become an essential tool for investigating the development and function of pattern generation networks in the spinal cord. Here we examine the development of the spinal segmental output by mapping the distribution of motoneuron activity in the lumbosacral spinal cord during stepping in newborns, toddlers, preschoolers, and adults. Newborn stepping is characterized by an alternating bilateral motor output with only two major components that are active at all lumbosacral levels of the spinal cord. This feature was similar across different cycle durations of neonate stepping. The alternating spinal motor output is consistent with a simpler organization of neuronal networks in neonates. Furthermore, a remarkable feature of newborn stepping is a higher overall activation of lumbar versus sacral segments, consistent with a rostrocaudal excitability gradient. In toddlers, the stance-related motor pool activity migrates to the sacral cord segments, while the lumbar motoneurons are separately activated at touchdown. In the adult, the lumbar and sacral patterns become more dissociated with shorter activation times. We conclude that the development of human locomotion from the neonate to the adult starts from a rostrocaudal excitability gradient and involves a gradual functional reorganization of the pattern generation circuitry.
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32
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Brooks JCW. Assessing spinal cord function in multiple sclerosis with functional neuroimaging: insights and limitations. Mult Scler 2012; 18:1517-9. [PMID: 23100521 DOI: 10.1177/1352458512450357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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33
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Reduction of physiological noise with independent component analysis improves the detection of nociceptive responses with fMRI of the human spinal cord. Neuroimage 2012; 63:245-52. [PMID: 22776463 DOI: 10.1016/j.neuroimage.2012.06.057] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 06/22/2012] [Accepted: 06/23/2012] [Indexed: 11/20/2022] Open
Abstract
The evaluation of spinal cord neuronal activity in humans with functional magnetic resonance imaging (fMRI) is technically challenging. Major difficulties arise from cardiac and respiratory movement artifacts that constitute significant sources of noise. In this paper we assessed the Correction of Structured noise using spatial Independent Component Analysis (CORSICA). FMRI data of the cervical spinal cord were acquired in 14 healthy subjects using gradient-echo EPI. Nociceptive electrical stimuli were applied to the thumb. Additional data with short TR (250 ms, to prevent aliasing) were acquired to generate a spatial map of physiological noise derived from Independent Component Analysis (ICA). Physiological noise was subsequently removed from the long-TR data after selecting independent components based on the generated noise map. Stimulus-evoked responses were analyzed using the general linear model, with and without CORSICA and with a regressor generated from the cerebrospinal fluid region. Results showed higher sensitivity to detect stimulus-related activation in the targeted dorsal segment of the cord after CORSICA. Furthermore, fewer voxels showed stimulus-related signal changes in the CSF and outside the spinal region, suggesting an increase in specificity. ICA can be used to effectively reduce physiological noise in spinal cord fMRI time series.
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34
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Assessment of physiological noise modelling methods for functional imaging of the spinal cord. Neuroimage 2012; 60:1538-49. [DOI: 10.1016/j.neuroimage.2011.11.077] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 10/26/2011] [Accepted: 11/25/2011] [Indexed: 11/22/2022] Open
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35
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Figley CR, Stroman PW. Measurement and characterization of the human spinal cord SEEP response using event-related spinal fMRI. Magn Reson Imaging 2012; 30:471-84. [PMID: 22285878 DOI: 10.1016/j.mri.2011.12.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 10/14/2011] [Accepted: 12/04/2011] [Indexed: 01/21/2023]
Abstract
Although event-related fMRI is able to reliably detect brief changes in brain activity and is now widely used throughout systems and cognitive neuroscience, there have been no previous reports of event-related spinal cord fMRI. This is likely attributable to the various technical challenges associated with spinal fMRI (e.g., imaging a suitable length of the cord, reducing image artifacts from the vertebrae and intervertebral discs, and dealing with physiological noise from spinal cord motion). However, with many of these issues now resolved, the largest remaining impediment for event-related spinal fMRI is a deprived understanding of the spinal cord fMRI signal time course. Therefore, in this study, we used a proton density-weighted HASTE sequence, with functional contrast based on signal enhancement by extravascular water protons (SEEP), and a motion-compensating GLM analysis to (i) characterize the SEEP response function in the human cervical spinal cord and (ii) demonstrate the feasibility of event-related spinal fMRI. This was achieved by applying very brief (1 s) epochs of 22°C thermal stimulation to the palm of the hand and measuring the impulse response function. Our results suggest that the spinal cord SEEP response (time to peak ≈8 s; FWHM ≈4 s; and probably lacking pre- and poststimulus undershoots) is slower than previous estimates of SEEP or BOLD responses in the brain, but faster than previously reported spinal cord BOLD responses. Finally, by detecting and mapping consistent signal-intensity changes within and across subjects, and validating these regions with a block-designed experiment, this study represents the first successful demonstration of event-related spinal fMRI.
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Affiliation(s)
- Chase R Figley
- Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
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36
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Giulietti G, Summers PE, Ferraro D, Porro CA, Maraviglia B, Giove F. Semiautomated segmentation of the human spine based on echoplanar images. Magn Reson Imaging 2011; 29:1429-36. [DOI: 10.1016/j.mri.2011.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 08/15/2011] [Accepted: 08/22/2011] [Indexed: 10/14/2022]
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37
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Cohen-Adad J, Mareyam A, Keil B, Polimeni JR, Wald LL. 32-channel RF coil optimized for brain and cervical spinal cord at 3 T. Magn Reson Med 2011; 66:1198-208. [PMID: 21433068 PMCID: PMC3131444 DOI: 10.1002/mrm.22906] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 01/12/2011] [Accepted: 02/14/2011] [Indexed: 11/09/2022]
Abstract
Diffusion and functional magnetic resonance imaging of the spinal cord remain challenging due to the small cross-sectional size of the cord and susceptibility-related distortions. Although partially addressable through parallel imaging, few highly parallel array coils have been implemented for the cervical cord. Here, we developed a 32-channel coil that fully covers the brain and c-spine and characterized its performance in comparison with a commercially available head/neck/spine array. Image and temporal signal-to-noise ratio were, respectively, increased by 2× and 1.8× in the cervical cord. Averaged g-factors at 4× acceleration were lowered by 22% in the brain and by 39% in the spinal cord, enabling 1-mm isotropic R = 4 multi-echo magnetization prepared gradient echo of the full brain and c-spine in 3:20 min. Diffusion imaging of the cord at 0.6 × 0.6 × 5 mm(3) resolution and tractography of the full brain and c-spine at 1.7-mm isotropic resolution were feasible without noticeable distortion. Improvements of this nature potentially enhance numerous basic and clinical research studies focused on spinal and supraspinal regions.
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Affiliation(s)
- J Cohen-Adad
- AA Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
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38
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Finsterbusch J, Eippert F, Büchel C. Single, slice-specific z-shim gradient pulses improve T2*-weighted imaging of the spinal cord. Neuroimage 2011; 59:2307-15. [PMID: 21979381 DOI: 10.1016/j.neuroimage.2011.09.038] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/09/2011] [Accepted: 09/14/2011] [Indexed: 10/17/2022] Open
Abstract
T2*-weighted imaging of the spinal cord suffers from signal dropouts that hamper blood-oxygenation-level-dependent functional magnetic resonance imaging (fMRI). They are due to field inhomogeneities caused by the different magnetic susceptibilities of the vertebrae and the intervertebral disks that vary periodically along the cord and, thus, cannot be compensated appropriately with conventional (constant) shimming. In this study, a single, slice-specific gradient pulse ("z-shim") is applied in echo-planar imaging of axial sections in order to compensate for the corresponding through-slice signal dephasing without affecting the acquisition time, i.e. the temporal resolution. Based on a reference acquisition sampling a range of compensation moments, the value yielding the maximum signal amplitude within the spinal cord is determined for each slice. Severe N/2 ghosting for larger compensation moments is avoided by applying the gradient pulse after the corresponding reference echoes. Furthermore, first-order flow compensation in the slice direction of both the slice-selection and the z-shim gradient pulse considerably reduces signal fluctuations in the cerebro-spinal fluid surrounding the spinal cord, i.e. would minimize ringing artifacts in fMRI. Phantom and in vivo experiments show the necessity to use slice-specific compensation moments in the presence of local susceptibility differences. Measurements performed in a group of 24 healthy volunteers at 3T demonstrate that this approach improves T2*-weighted imaging of axial sections of the cervical spinal cord by (i) increasing the signal intensity (overall by about 20%) and (ii) reducing signal intensity variations along the cord (by about 80%). Thus, it may help to improve the feasibility and reliability of fMRI of the spinal cord.
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Affiliation(s)
- Jürgen Finsterbusch
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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39
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Schweinhardt P, Bushnell MC. Pain imaging in health and disease--how far have we come? J Clin Invest 2010; 120:3788-97. [PMID: 21041961 DOI: 10.1172/jci43498] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Since modern brain imaging of pain began 20 years ago, networks in the brain related to pain processing and those related to different types of pain modulation, including placebo, have been identified. Functional and anatomical connectivity of these circuits has begun to be analyzed. Imaging in patients suggests that chronic pain is associated with altered function and structural abnormalities in pain modulatory circuits. Moreover, biochemical alterations associated with chronic pain are being identified that provide information on cellular correlates as well as potential mechanisms of structural changes. Data from these brain imaging studies reinforce the idea that chronic pain leads to brain changes that could have functional significance.
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Affiliation(s)
- Petra Schweinhardt
- Department of Anesthesia, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
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40
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Summers PE, Iannetti GD, Porro CA. Functional exploration of the human spinal cord during voluntary movement and somatosensory stimulation. Magn Reson Imaging 2010; 28:1216-24. [PMID: 20573462 DOI: 10.1016/j.mri.2010.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 04/21/2010] [Accepted: 05/08/2010] [Indexed: 11/30/2022]
Abstract
Demonstrations of the possibility of obtaining functional information from the spinal cord in humans using functional magnetic resonance imaging (fMRI) have been growing in number and sophistication, but the technique and the results that it provides are still perceived by the scientific community with a greater degree of scepticism than fMRI investigations of brain function. Here we review the literature on spinal fMRI in humans during voluntary movements and somatosensory stimulation. Particular attention is given to study design, acquisition and statistical analysis of the images, and to the agreement between the obtained results and existing knowledge regarding spinal cord anatomy and physiology. A striking weakness of many spinal fMRI studies is the use of small numbers of subjects and of time-points in the acquired functional image series. In addition, spinal fMRI is characterised by large physiological noise, while the recorded functional responses are poorly characterised. For all these reasons, spinal fMRI experiments risk having low statistical power, and few spinal fMRI studies have yielded physiologically relevant information. Thus, while available evidence indicates that spinal fMRI is feasible, we are only approaching the stage at which the technique can be considered to have been rigorously established as a viable means of noninvasively investigating spinal cord functioning in humans.
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Affiliation(s)
- Paul E Summers
- Dipartimento di Scienze Biomediche, Univ. Modena e Reggio Emilia, Modena, Italy.
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41
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Brieu N, Beaumont E, Dubeau S, Cohen-Adad J, Lesage F. Characterization of the hemodynamic response in the rat lumbar spinal cord using intrinsic optical imaging and laser speckle. J Neurosci Methods 2010; 191:151-7. [PMID: 20600322 DOI: 10.1016/j.jneumeth.2010.06.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 05/28/2010] [Accepted: 06/11/2010] [Indexed: 10/19/2022]
Abstract
Quantifying spinal cord functions is crucial for understanding neurophysiological mechanisms governing the intact and the injured spinal cord. Intrinsic optical imaging (IOI) and laser speckle provides measures of deoxyhemoglobin (HbR) and oxyhemoglobin (HbO(2)) concentrations, blood volume (BV) and blood flow (BF) at high spatial and temporal resolution. In this study we used IOI and laser speckle to characterize the hemodynamic response to neuronal activation in the lumbar spinal cord of anaesthetized rats (N=9). We report consistent temporal variations of HbR, HbO(2), BV and BF located ipsilaterally at L3-L5. Responses were significantly higher when stimulation intensity was increased. Vascular changes extended several millimetres from the epicenter, supporting the venous drainage observed in functional magnetic resonance imaging studies.
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Affiliation(s)
- Nicolas Brieu
- Département de génie électrique, Ecole Polytechnique de Montréal, Montreal, QC, Canada
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42
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A quantitative comparison of BOLD fMRI responses to noxious and innocuous stimuli in the human spinal cord. Neuroimage 2010; 50:1408-15. [DOI: 10.1016/j.neuroimage.2010.01.043] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 12/07/2009] [Accepted: 01/13/2010] [Indexed: 11/22/2022] Open
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43
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Leitch JK, Figley CR, Stroman PW. Applying functional MRI to the spinal cord and brainstem. Magn Reson Imaging 2010; 28:1225-33. [PMID: 20409662 DOI: 10.1016/j.mri.2010.03.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 03/07/2010] [Accepted: 03/11/2010] [Indexed: 12/28/2022]
Abstract
Functional magnetic resonance imaging of the spinal cord (spinal fMRI) has facilitated the noninvasive visualization of neural activity in the spinal cord (SC) and brainstem of both animals and humans. This technique has yet to gain the widespread usage of brain fMRI, due in part to the intrinsic technical challenges spinal fMRI presents and to the narrower scope of applications it fulfills. Nonetheless, methodological progress has been considerable and rapid. To date, spinal fMRI studies have investigated SC function during sensory or motor task paradigms in spinal cord injury (SCI), multiple sclerosis (MS) and neuropathic pain (NP) patient populations, all of which have yielded consistent and sensitive results. The most recent study in our laboratory has successfully used spinal fMRI to examine cervical SC activity in a SCI patient with a metallic fixation device spanning the C(4) to C(6) vertebrae, a critical step in realizing the clinical utility of the technique. The literature reviewed in this article suggests that spinal fMRI is poised for usage in a wide range of patient populations, as multiple groups have observed intriguing, yet consistent, results using standard, readily available MR systems and hardware. The next step is the implementation of this technique in the clinic to supplement standard qualitative behavioral assessments of SCI. Spinal fMRI may offer insight into the subtleties of function in the injured and diseased SC, and support the development of new methods for treatment and monitoring.
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Affiliation(s)
- Jordan K Leitch
- Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
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44
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BOLD signal responses to controlled hypercapnia in human spinal cord. Neuroimage 2010; 50:1074-84. [DOI: 10.1016/j.neuroimage.2009.12.122] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Revised: 12/08/2009] [Accepted: 12/31/2009] [Indexed: 01/21/2023] Open
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45
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Resting state networks in human cervical spinal cord observed with fMRI. Eur J Appl Physiol 2009; 108:265-71. [DOI: 10.1007/s00421-009-1205-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2009] [Indexed: 10/20/2022]
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46
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Malisza KL, Jones C, Gruwel MLH, Foreman D, Fernyhough P, Calcutt NA. Functional magnetic resonance imaging of the spinal cord during sensory stimulation in diabetic rats. J Magn Reson Imaging 2009; 30:271-6. [PMID: 19629995 DOI: 10.1002/jmri.21856] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
PURPOSE To determine if differences exist between control and diabetic rats in functional magnetic resonance imaging (fMRI) activity of the spinal cord and if fMRI can provide a means of early detection of diabetic neuropathy. MATERIALS AND METHODS fMRI of the spinal cord, using noxious electrical stimulation (15 V ( approximately 8 mA), 0.3 msec, 3 Hz) of the hind paw, was performed in groups of control and streptozotocin (STZ)-induced type 1 diabetic rats. RESULTS Diabetic rats were lighter, hyperglycemic, and had lower blood pH than controls. fMRI activity at the lumbar enlargement of the spinal cord was identified in the dorsal horn ipsilateral to stimulus of all animals. Signal intensity changes across the lumbar spinal cord during periods of activity were not significantly different between control and diabetic rats, with a trend toward greater signal changes in controls. When specific regions of the spinal cord were analyzed, control rats exhibited significantly increased blood-oxygen level-dependent (BOLD) fMRI activity in both ipsilateral and contralateral dorsal horn compared to diabetic rats. CONCLUSION The results of this study are consistent with reports that primary afferent input to the spinal cord is diminished by diabetes, and suggest that BOLD fMRI may be useful in early detection of diabetic neuropathy.
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Affiliation(s)
- Krisztina L Malisza
- National Research Council, Institute for Biodiagnostics, Winnipeg, MB, Canada.
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47
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Xie CH, Kong KM, Guan JT, Chen YX, He JK, Qi WL, Wang XJ, Shen ZW, Wu RH. SSFSE sequence functional MRI of the human cervical spinal cord with complex finger tapping. Eur J Radiol 2009; 70:1-6. [PMID: 18353589 DOI: 10.1016/j.ejrad.2008.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 10/05/2007] [Accepted: 01/10/2008] [Indexed: 02/05/2023]
Abstract
PURPOSE Functional MR imaging of the human cervical spinal cord was carried out on volunteers during alternated rest and a complex finger tapping task, in order to detect image intensity changes arising from neuronal activity. METHODS Functional MR imaging data using single-shot fast spin-echo sequence (SSFSE) with echo time 42.4 ms on a 1.5 T GE Clinical System were acquired in eight subjects performing a complex finger tapping task. Cervical spinal cord activation was measured both in the sagittal and transverse imaging planes. Postprocessing was performed by AFNI (Analysis of Functional Neuroimages) software system. RESULTS Intensity changes (5.5-7.6%) were correlated with the time course of stimulation and were consistently detected in both sagittal and transverse imaging planes of the cervical spinal cord. The activated regions localized to the ipsilateral side of the spinal cord in agreement with the neural anatomy. CONCLUSION Functional MR imaging signals can be reliably detected with finger tapping activity in the human cervical spinal cord using a SSFSE sequence with 42.4 ms echo time. The anatomic location of neural activity correlates with the muscles used in the finger tapping task.
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Affiliation(s)
- Chu-hai Xie
- Department of Orthopedic Surgery, The Second Affiliated Hospital to Shantou University Medical College, Shantou, Guangdong 515041, China.
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48
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Spinal cord functional MRI at 3 T: Gradient echo echo-planar imaging versus turbo spin echo. Neuroimage 2008; 43:288-96. [DOI: 10.1016/j.neuroimage.2008.07.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 07/01/2008] [Accepted: 07/02/2008] [Indexed: 11/22/2022] Open
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49
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Characterization of cardiac-related noise in fMRI of the cervical spinal cord. Magn Reson Imaging 2008; 27:300-10. [PMID: 18801632 DOI: 10.1016/j.mri.2008.07.019] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 06/25/2008] [Accepted: 07/30/2008] [Indexed: 12/28/2022]
Abstract
Magnetic resonance imaging (MRI) has recently been applied to study spinal cord function in humans. However, spinal functional MRI (fMRI) encounters major technical challenges with cardiac noise being considered a major source of noise. The present study relied on echo-planar imaging of the cervical cord at short TR (TR=250 ms; TE=40 ms; flip=45 degrees), combined with plethysmographic recordings to characterize the spatiotemporal properties of cardiac-induced signal changes in spinal fMRI. Frequency-based analyses examining signal change at the cardiac frequency confirmed mean fluctuations of about 10% (relative to the mean signal) in the spinal cord and surrounding cerebrospinal fluid (CSF), with maximal responses reaching up to 66% in some voxels. A spatial independent component analysis (sICA) confirmed that cardiac noise is an important source of variance in spinal fMRI with several components showing a response coherent with the cardiac frequency spectrum. The time course of the main cardiac components approximated a sinusoidal function tightly coupled to the cardiac systole with at least one component showing a comparable temporal profile across runs and subjects. Spatially, both the frequency-domain analysis and the sICA demonstrated cardiac noise distributed irregularly along the full rostrocaudal extent of the segments scanned with peaks concentrated in the ventral part of the lateral slices in all scans and subjects, consistent with the major channels of CSF flow. These results confirm that cardiac-induced changes are a significant source of noise likely to affect the detection of spinal Blood Oxygen Level Dependent (BOLD) responses. Most importantly, the complex spatiotemporal structure of cardiac noise is unlikely to be accounted for adequately by ad hoc linear methods, especially in data acquired using long TR (i.e. aliasing the cardiac frequency). However, the reliable spatiotemporal distribution of cardiac noise across scanning runs and within subjects may provide a valid means to identify and extract cardiac noise based on sICA methods.
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Characterization of the functional response in the human spinal cord: Impulse-response function and linearity. Neuroimage 2008; 42:626-34. [DOI: 10.1016/j.neuroimage.2008.05.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 03/28/2008] [Accepted: 05/01/2008] [Indexed: 11/22/2022] Open
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