Joseph Allan Borrello^1,2,3, Joo-won Kim^2,4, Mootaz Eldib^2,4, and Junqian Xu^2,4,5
1Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ²Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ³Mount Sinai Institute of Technology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ⁴Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ⁵Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States

Spinal cord cross sectional area (SCCSA) holds promise as a biomarker of neurological disorders. However, the large FOVs required to obtain SCCSA from a large portions of the spinal cord are accompanied by significant spatial distortions due to gradient nonlinearity. While MRI vendors supply spatial unwarping algorithms, site-specific variations in the gradient linearity are present, which affects the reproducibility of longitudinal and multi-site studies. We have fabricated an in situ phantom designed to provide a spatial point of reference, in conjunction with numerically optimizing the unwarping with measurements at two table positions, to provide scanner-specific gradient non-linearity unwarping.

Benjamin De Leener¹, Manuel Taso^2,3, Vladimir Fonov⁴, Arnaud Le Troter^2,3, Nikola Stikov^1,5, Louis Collins⁴, Virginie Callot^2,3, and Julien Cohen-Adad^1,6
1Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada, ²Centre de Résonance Magnétique Biologique et Médicale (CRMBM), UMR 7339, Aix-Marseille Université (AMU), CNRS, Marseille, France, ³Centre d'Exploration Métabolique par Résonance Magnétique (CEMEREM), Hôpital de la Timone, AP-HM, Marseille, France, ⁴Montreal Neurological Institute (MNI), McGill University, Montreal, QC, Canada, ⁵Montreal Heart Institute, Montreal, QC, Canada, ⁶Functional Neuroimaging Unit, CRIUGM, Universite´ de Montre´al, Montreal, QC, Canada

The spinal cord MRI community currently lacks a standard reference template covering the entire cord, therefore hindering the feasibility of large multi-center studies. Here, we propose the MNI-Poly-AMU50, the first MRI template of the entire spinal cord and brainstem, based on 50 subjects, available for multiple contrasts (T₁-, T₂- and T₂*-weighted), and integrating probabilistic atlases of the white and gray matter. These templates provide a common framework for co-registering multi-parametric data. All developments are freely available as part of the Spinal Cord Toolbox.

Aurélien Massire^1,2,3, Manuel Taso^1,2,3,4, Maxime Guye^1,2, Jean-Philippe Ranjeva^1,2,3, and Virginie Callot^1,2,3
1Centre de Résonance Magnétique Biologique et Médicale (CRMBM), UMR 7339, CNRS, Aix-Marseille Université, Marseille, France, ²Centre d'Exploration Métabolique par Résonance Magnétique (CEMEREM), Hôpital de la Timone, Pôle d’imagerie médicale, AP-HM, Marseille, France, ³iLab-Spine - Laboratoire international - Imagerie et Biomécanique du rachis, Marseille, France, ⁴LBA, UMR T24, Aix-Marseille Université, IFSTTAR, Marseille, France

A high-resolution multi-parametric MRI protocol dedicated to 7T cervical spinal cord (SC) investigation using a commercial prototype transceiver radiofrequency coil array is proposed. This work pushes forward SC quantitative MRI by reporting T₁/T₂/T₂^* relaxation times mapping as well as diffusion tensor imaging metrics at the C3 cervical level on a cohort of ten healthy volunteers. Automatic segmentation and registration of these multi-parametric acquisitions to SC templates enable group studies with quantitative evaluation within regional WM tracts and GM horns never reported so far at 7T. This study lays the groundwork for improved characterization of degenerative SC pathologies at ultra-high field.

Henry Szu-Meng Chen¹, Nathan Holmes², Wolfram Tetzlaff^2,3, and Piotr Kozlowski^4,5
1Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada, ²Zoology, University of British Columbia, Vancouver, BC, Canada, ³ICORD, Vancouver, BC, Canada, ⁴UBC MRI Research Centre, Vancouver, BC, Canada, ⁵Radiology, University of British Columbia, Vancouver, BC, Canada

Quantitative T2 based myelin water imaging measures myelin content by probing the properties of the water trapped in myelin and therefore depends on its morphology. We compared MR myelin water fraction (MWF) to electron microscopy derived myelin content using a rat injury model and found that MWF correlates strongly with the amount of myelin lipid bilayers in both intact myelin and myelin debris and that myelin debris appears to consist of areas of either normally spaced myelin or large vacuous spaces. No significant differences were found in myelin spacing among normal, 3 week, and 8 weeks post injury time points.

Sara Dupont¹, Benjamin De Leener¹, Manuel Taso^2,3, Nikola Stikov^1,4, Virginie Callot^2,3, and Julien Cohen-Adad^1,5
1Neuroimaging Research Laboratory (NeuroPoly), Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, QC, Canada, ²Centre de Résonance Magnétique Biologique et Médicale (CRMBM), UMR 7339, CNRS, Aix-Marseille Université, Marseille, France, ³Centre d'Exploration Métabolique par Résonance Magnétique (CEMEREM), Hôpital de la Timone, AP-HM, Marseille, France, ⁴Montreal Heart Institute (MHI), Montréal, QC, Canada, ⁵Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montréal, QC, Canada

The spinal cord (SC) white and gray matter can be affected by a large number of pathologies. Being able to segment precisely the SC internal structure would be useful to better understand SC diseases, improve diagnosis and assess treatment efficiency. We introduce a complete framework for (i) multi-atlas automatic segmentation of the gray-matter, (ii) accurate registration to the MNI-Poly-AMU template and (iii)extraction of quantitative metric using partial volume information. Results showed improved accuracy of template registration when adding prior automatic gray-matter segmentation. The proposed method is freely available and provides an unbiased framework for quantitative analysis of SC MRI data.

Ferran Prados^1,2, Manuel Jorge Cardoso¹, Marios C Yiannakas², Luke R Hoy², Elisa Tebaldi², Hugh Kearney², Martina D Liechti², David H Miller², Olga Ciccarelli², Claudia Angela Michela Gandini Wheeler-Kingshott^2,3, and Sebastien Ourselin^1
1Translational Imaging Group, Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, ²NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, United Kingdom, ³Brain Connectivity Center, C. Mondino National Neurological Institute, Pavia, Italy

We propose and validate a new fully automated spinal cord (SC) segmentation technique that incorporates two different multi-atlas segmentation propagation and fusion techniques: Optimized PatchMatch Label fusion (OPAL) and Similarity and Truth Estimation for Propagated Segmentations (STEPS). We collaboratively join the advantages of each method to obtain the most accurate SC segmentation. The new method reaches the inter-rater variability, providing automatic segmentations equivalents to inter-rater segmentations in terms of DSC 0.97 for whole cord for any subject.

Alex K. Smith^1,2, Richard D. Dortch^1,2,3, Samantha By^1,2, Robert L. Barry², Chris R. Thompson², Kristen George-Durrett², Bailey D. Lyttle², and Seth A. Smith^1,2,3
1Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, ²Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, ³Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States

The spinal cord is responsible for mediating neurologic function, and in particular, the lumbar cord is integral to lower extremity function.  However, lumbar cord quantitative MRI studies have been limited due to its size, location, and composition.  A single-point quantitative magnetization transfer was recently developed, but has not been applied to the lumbar cord.  Therefore, we have implemented an assessment of qMT at the thoracolumbar bulge to characterize the MT effect in the thoracolumbar cord in healthy volunteers.

Tsen-Hsuan Lin¹, Mitchell Hallman^1,2, Fay Hwang¹, Yong Wang^1,3,4,5, Sheng-Kwei Song^1,4,5, and Peng Sun^1
1Radiology, Washington University School of Medicine, St. Louis, MO, United States, ²Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States, ³Obstertic and Gynecology, Washington University School of Medicine, St. Louis, MO, United States, ⁴The Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, United States, ⁵Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States

The extent of axonal loss plays a significant role in irreversible neurological impairment in spinal cord injury (SCI). We detected a 15% axonal loss in SCI mice using diffusion basis spectrum imaging (DBSI) that was masked by injury induced white matter swelling.    

Benjamin A Walter^1,2, Prasath Mageswaran^1,3, Hazem Mashaly^1,4, William Thoman ^1,4, Daniel Boulter⁵, Luciano Prevedello ⁵, Xuan Nguyen ⁵, Mo Xiaokui ⁶, Ehud Mendel ^1,4, William Marras^1,3, and Arunark Kolipaka^1,2,5,7
1Spine Research Institute, The Ohio State University, Columbus, OH, United States, ²Biomedical Engineering, The Ohio State University, Columbus, OH, United States, ³Integrated Systems Engineering, The Ohio State University, Columbus, OH, United States, ⁴Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, United States, ⁵Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States, ⁶Biomedical Informatics, The Ohio State University, Columbus, OH, United States, ⁷Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States

Magnetic resonance elastography (MRE) was used to assess intervertebral disc (IVD) shear properties in order to develop an objective biomarker for the IVD degeneration process.  This study characterized the frequency response and repeatability of MRE assessment of IVD shear stiffness and how the shear stiffness of the nucleus pulposus (NP) region of the IVD changes during degeneration. Results suggest that MRE derived NP shear stiffness is a repeatable technique that can provide a relative and objective measurement of IVD degeneration that is independent of age.

Ilwoo Park¹, Jeremy Gordon¹, Sarah Nelson^1,2, and Jason Talbott^1,3
1Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States, ²Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, United States, ³Brain and Spine Injury Center (BASIC), University of California San Francisco, San Francisco, CA, United States

This study has demonstrated the feasibility of using hyperpolarized ¹³C MRI with [¹³C]t-butanol and [¹³C,¹⁵N₂]urea for assessing in vivo perfusion in the cervical spinal cord. T-butanol rapidly crossed the blood-brain-barrier and diffused into spine and brain tissue, while urea predominantly remained in vasculature. The results from this study suggest that this technique may provide unique non-invasive imaging tracers that are able to directly monitor hemodynamic processes in the normal and injured spinal cord.