Kurt Schilling¹, Anna J.E. Combes², Logan Prock², Kristin P. O'Grady¹, Bennett A Landman², and Seth A Smith^1
1Vanderbilt University Medical Center, Nashville, TN, United States, ²Vanderbilt University, Nashville, TN, United States

The aim of this study was to evaluate acquisition and preprocessing strategies for diffusion MRI in the cervical spinal cord. We tested 6 acquisition and 5 preprocessing strategies, and quantified evaluation criteria, and found that pipelines that include distortion correction significantly improve data quality. However, motion and lack of cardiac triggering significantly impact quality measures. Standard diffusion processing packages need to be adapted and modified for spinal cord microstructure to ensure accurate and robust diffusion quantification. 

KiChang Kang¹, Kristen Fleming¹, Anish V. Sathe¹, Jennifer Muller¹, Devon Middleton¹, Feroze Mohamed¹, Laura Krisa¹, and Mahdi Alizadeh^1
1Thomas Jefferson University, Philadelphia, PA, United States

Little is known about microstructural alterations in the thalamus following spinal cord injury (SCI), especially in the pediatric population. In this study, we used diffusion tensor imaging (DTI) derived metrics to characterize microstructural changes in thalamic nuclei of pediatric subjects with chronic SCIs with respect to the severity of injury based on the American Spinal Injury Association Impairment Scale (AIS). We report significant differences in mean diffusion metrics in thalamic nuclei that are suggestive of microstructural alterations between different AIS classifications.

Sarah Rosemary Morris^1,2,3, Taylor Swift-LaPointe², Andrew Yung^1,3,4, Valentin Prevost^1,3,4, Shana George¹, Andrew Bauman⁴, Piotr Kozlowski^1,2,3,4, Farah Samadi^1,5, Caron Fournier^1,5, Lisa Parker⁶, Kevin Dong¹, Femke Streijger¹, Veronica Hirsch-Reinshagen^1,5,6, G.R. Wayne Wayne Moore^1,5,6, Brian K Kwon^1,7, and Cornelia Laule^1,2,3,5
1International Collaboration on Repair Discoveries (ICORD), Vancouver, BC, Canada, ²Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada, ³Radiology, University of British Columbia, Vancouver, BC, Canada, ⁴Faculty of Medicine, UBC MRI Research Centre, Vancouver, BC, Canada, ⁵Pathology & Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada, ⁶Vancouver General Hospital, Vancouver, BC, Canada, ⁷Orthopaedics, University of British Columbia, Vancouver, BC, Canada

We investigated the correlation of inhomogeneous magnetisation transfer ratio (ihMTR), myelin water fraction (MWF) and intra/extra-cellular water geometric mean T₂ (I/EW gmT₂) with the distribution of inflammatory cells as measured by HLA-DR and CD68 histological staining for macrophages and activated microglia in human traumatic spinal cord injury. We found that ihMTR and MWF decreases were strongly correlated with the presence of HLA/CD68+ immune cells in white matter and both ihMTR and MWF were strongly correlated with LFB, a stain for myelin lipids. Our results demonstrate a strong link between ihMTR and MWF and inflammation.

Sharada Balaji¹, Adam Dvorak¹, Neale Wiley¹, Laura Barlow², Irene M. Vavasour^3,4, Alex MacKay^1,3, and Shannon H. Kolind^1,3,4,5
1Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada, ²MRI Research Centre, University of British Columbia, Vancouver, BC, Canada, ³Radiology, University of British Columbia, Vancouver, BC, Canada, ⁴International Collaboration on Repair Discoveries, Vancouver, BC, Canada, ⁵Medicine, University of British Columbia, Vancouver, BC, Canada

The standard myelin water imaging (MWI) sequence for cervical spinal cord, 3D gradient and spin echo (GRASE), was modified to allow scanning in “normal mode” (limiting imaging parameters that may cause physiologic stress) for patients who may not tolerate peripheral nerve stimulation or tissue heating due to MR-conditional implants or medical issues. Traditional 32-echo GRASE was replaced with 48-echo GRASE in normal mode. Myelin water fraction maps from the new sequence had better repeatability than the standard sequence. 48-echo GRASE is the recommended sequence for MWI in spinal cord, particularly for subjects who cannot be scanned outside of normal mode.

Silvan Büeler¹, Patrick Freund², Thomas M. Kessler¹, Martina D. Liechti¹, and Gergely David^1,2
1Department of Neuro-Urology, Balgrist University Hospital, University of Zürich, Zürich, Switzerland, ²Spinal Cord Injury Center, Balgrist University Hospital, University of Zürich, Zürich, Switzerland

Imaging of the lumbosacral enlargement (LSE) has previously demonstrated remote degeneration below a cervical spinal cord injury leading to progressive atrophy of grey and white matter. Here, we investigate, for the first time, neurodegeneration in the conus medullaris (including the LSE) after acute spinal cord injury using an optimized multi-echo gradient-echo sequence. At 1-month after injury, preliminary results show lower grey matter volume in the conus medullaris. This is the first MRI investigation indicating remote tissue-specific volumetric changes in the conus medullaris in spinal cord injury.

Tim Max Emmenegger¹, Dario Pfyffer¹, Simon Schading¹, Alan Thompson², Gabriel Ziegler^3,4, John Ashburner⁵, Karl Friston⁵, Nikolaus Weiskopf⁶, Armin Curt¹, and Patrick Freund^1,5,6,7
1Spinal Cord Injury Center, Balgrist University Hospital Zurich, University of Zurich, Zurich, Switzerland, ²Queen Square Multiple Sclerosis Centre, Institute of Neurology, University College London, London, United Kingdom, ³Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany, ⁴German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, ⁵Wellcome Centre for Human Neuroimaging, Queen Square Institute of Neurology, University College London, London, United Kingdom, ⁶Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, ⁷Department of Brain Repair and Rehabilitation,, Queen Square Institute of Neurology, University College London, London, United Kingdom

Traumatic spinal cord injury (SCI) triggers a cascade of neurodegenerative events across the neuroaxis. The trajectories of lesion characteristics and brain and spinal cord macro-and microstructural changes were analysed over five years in 23 SCI patients and 21 healthy controls. Initially, SCI patients showed higher volume and iron content in the spinal cord which decreased over time. They showed lower myelin-sensitive MTsat values in the dorsal column and cortex which also decreased over time and were associated with acute lesion characteristics. These observations illustrate the widespread and progressive neuroplastic processes after SCI, its magnitude being predicted by acute lesion characteristics.

Guillaume Frébourg^1,2,3, Kaissar Farah⁴, Thomas Troalen⁵, Lauriane Pini^1,3, Aurélien Destruel^1,2,3, Stéphane Fuentes⁴, Maxime Guye^1,3, and Virginie Callot^1,2,3
1Aix-Marseille University, CNRS, CRMBM, Marseille, France, ²iLab-Spine International Associated Laboratory, Marseille-Montréal, France, ³AP-HM, Hôpital de la Timone, CEMEREM, Marseille, France, ⁴AP-HM, Hôpital Timone, Neurosurgery Dept., Marseille, France, ⁵Siemens Healthcare SAS, Saint-Denis, France

3T T1-GRASP acquisition combined with an optimized dynamic radial streaking artefacts reduction have been set up to analyze Dynamic Contrast Enhanced MRI (DCE) over time and spinal cord levels. Acquisition with Gd-injection using the best temporal resolution parameters have been applied on two healthy volunteers and one patient showing perfusion dysfunction with compression. Semi-quantitative parameters (SQP) have been calculated in different regions of interest along the cervical levels and voxel-wise to provide SQP axial mapping of the spinal cord.

Anna JE Combes^1,2, Anirban Sengupta^1,2, Baxter P Rogers^1,2, Delaney Houston¹, Logan Prock¹, Francesca Bagnato³, Colin D McKnight³, John C Gore^1,2,4, Seth A Smith^1,2,4, and Kristin P O'Grady^1,2
1Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, ²Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, ³Neurology, Vanderbilt University Medical Center, Nashville, TN, United States, ⁴Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

3D multishot GRE resting-state BOLD-sensitive images of the lumbar spinal cord were acquired in 10 healthy participants as part of a functional MRI (fMRI) protocol. Temporal SNR in the gray matter (GM) was 18.2±4.3 after post-processing. Average correlations at rest were 0.49±0.17 between ventral horns, and 0.55±0.13 between dorsal horns, and could be detected at the single-subject level using seed-based analysis. Independent Component Analysis in 6 subjects, each scanned on two different occasions, identified network nodes within GM that were consistent across sessions. FMRI of the lumbar spine is feasible and may reflect functional integrity of the lumbar cord.

Michela Fratini¹, Laura Maugeri², Maria Guidi³, Mauro Di Nuzzo⁴, Marta Moraschi⁵, Fabio Mangini⁶, Irene Egidi³, Daniele Mascali⁴, Valerio Pisani⁶, Ugo Nocentini⁶, and Federico Giove^4
1CNR- Nanotec, Roma, Italy, ²CNR- Nanotec, Lecce, Italy, ³Enrico Fermi Reserch Centre, Rome, Italy, ⁴CREF-Centro Fermi, Roma, Italy, ⁵campus biomedico, Roma, Italy, ⁶fondazione Santa Lucia, Roma, Italy

Functional Magnetic Resonance Imaging (fMRI) has become one of the most powerful tools in neuroscience research, with promising applications in clinical practice. Particularly, fMRI based on blood oxygenation level dependent (BOLD) contrast has gained a primary role in the study of human brain and spinal cord, for the characterization of normal and pathological brain/spinal cord (SC) activity. In this framework, we have studied and report the characterization of the functional response of the SC to a multilevel motor task, designed to assess the linearity of the hemodynamic response as a function of the intensity of a graded task.

Anna JE Combes^1,2, Kristin P O'Grady^1,2, Baxter P Rogers^1,2, Wuraola Adesinasi³, Logan Prock¹, Delaney Houston¹, Hamid Shah³, David Edwards⁴, Silky Chotai³, Byron F Stephens⁵, Li Min Chen^1,2, Seth A Smith^1,2,6, and John C Gore^1,2,6
1Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, ²Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, ³Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN, United States, ⁴Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, United States, ⁵Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, United States, ⁶Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

Spinal cord stenosis presents with highly variable clinical manifestations and prognoses. Resting-state functional MRI of the cord could provide complementary information in addition to structural measures. We sought to determine whether functional connectivity (FC) measures were altered in patients with compression of the lower cervical spinal cord, and whether those were related to morphometric measures at and above the level of pathology. Compression in the lower segments was significantly associated with lower FC of the ventral and dorsal networks in patients. This finding is a first step in exploring the FC features of the cord in compressive pathology.

Kimberly J. Hemmerling^1,2, Mark A. Hoggarth², Todd Parrish³, and Molly G. Bright^1,2
1Biomedical Engineering, Northwestern University, Evanston, IL, United States, ²Physical Therapy & Human Movement Sciences, Northwestern University, Chicago, IL, United States, ³Department of Radiology, Northwestern University, Chicago, IL, United States

Denoising of spinal cord fMRI data is important to address physiological noise confounds. Heatmaps used to visualize structured variance in spinal cord fMRI data reveal a unique artifact of aliased cardiac signals from pulsatile flow adjacent to the cord, which appears to travel along the longitudinal cord axis. Cardiac-related RETROICOR noise maps indicate that this artifact is successfully modeled and removed. The artifact velocity along the length of the spinal cord was calculated and is moderately correlated to the heart rate. This artifact may also provide insight into CSF flow in the spinal canal.

Alan C Seifert^1,2,3 and S Johanna Vannesjo^4
1Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ²Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ³Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ⁴Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway

A physiological noise model (PNM) is crucial for maximizing sensitivity and specificity to activation in 7T spinal cord fMRI.  The PNM must balance exhaustive modeling of non-BOLD signal, preservation of degrees of freedom, and avoidance of nuisance regressors that may be correlated with the task.  We compared four candidate PNMs.  A 37-term PNM and a 35-term PNM excluding heart rate and respiratory volume per unit time, which may be correlated with the task, performed approximately equally well.  A 32-term PNM containing only regressors derived from physiological recordings, and a 3-term PNM containing only image-derived regressors, were also evaluated. 

Aurelien Destruel^1,2,3, Pierre Jomin⁴, Tobias Wichmann⁵, Maxime Guye^1,2, Redha Abdeddaim ⁴, and Virginie Callot^1,2,3
1Aix-Marseille Université, CNRS, CRMBM, Marseille, France, ²AP-HM, Hôpital de la Timone, Pôle d'imagerie médicale, CEMEREM, Marseille, France, ³iLab-Spine - Laboratoire international associé - Imagerie et Biomécanique du rachis, Canada/, France, ⁴Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, Marseille, France, ⁵RAPID Biomedical GmbH, Rimpar, Germany

Parallel transmission for 7T MRI of the spinal cord is a promising area of research, as high specific absorption rate and coil inefficiency in some levels may limit certain applications. In the absence of virtual observation points (VOP) provided by the coil manufacturer, preliminary testing and first in vivo applications on a healthy volunteer were done in a conservative SAR-restricted, showing potential in regions that suffered from signal drops with the default shim parameters. The workflow to ensure radiofrequency safety with virtual observation points, based on simulations of the specific absorption rate and their validation, is also described.

Arash Forodighasemabadi^1,2,3,4, Guillaume Baucher^1,2,5, Lucas Soustelle^1,2, Thomas Troalen⁶, Olivier Girard^1,2, Guillaume Duhamel^1,2, Jean-Philippe Ranjeva^1,2, Maxime Guye^1,2, Jean-Baptiste Grisoli⁷, and Virginie Callot^1,2,4
1Aix-Marseille Univ, CNRS, CRMBM, Marseille, France, ²APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France, ³Aix-Marseille Univ, Université Gustave Eiffel, LBA, Marseille, France, ⁴iLab-Spine International Associated Laboratory, Marseille-Montreal, Marseille, France, ⁵APHM, Hopital Universitaire Nord, Neurosurgery Dept, Marseille, France, ⁶Siemens Healthcare SAS, Saint-Denis, France, ⁷APHM, Hopital Universitaire Timone, Pole MPR, Marseille, France

Brain alterations due to cumulative effects of impacts have been reported in rugby players. However, literature on long-term effects is scarce, and no study has been conducted to characterize potential spinal cord impairments.

In this study using a multiparametric MR protocol dedicated to both brain and cord, and combining state-of-the-art T₁ relaxometry and ihMT imaging, we observed diffuse T₁ increase in the cervical spinal cord, together with increased T₁ and decreased ihMTsat in specific brain WM tracts in retired players.

These preliminary results also suggest early aging, tissue degeneration, iron accumulation, and different aging processes in retired players.

Colline Blanc^1,2, Shiva Shahrampour³, Feroze Mohamed³, and Benjamin De Leener^1,2,4
1NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montreal, QC, Canada, Montreal, QC, Canada, ²Research Center, Ste-Justine Hospital University Centre, Montreal, QC, Canada, Montreal, QC, Canada, ³Thomas Jefferson University, Philadelphia, PA, United States, Philadelphia, PA, United States, ⁴Department of Computer and Software Engineering, Polytechnique Montréal, Montréal, QC, Canada, Montreal, QC, Canada

Segmentation of the spinal cord is an essential process for the accurate delineation of spinal cord structures. However, it is a long process and automatic segmentation tools are not adapted to segment the pediatric spinal cord. We therefore developed a tool mixing a neural network and a deterministic method to overcome the limitations. We succeeded in obtaining a segmentation with a dice coefficient of 0.86 on a patient with a spinal cord injury (SCI).