Manuel Taso^1,2, Olivier M. Girard^3,4, Guillaume Duhamel^3,4, Arnaud Le Troter^3,4, Guilherme Ribeiro^3,4, Thorsten Feiweier⁵, Maxime Guye^3,4, Jean-Philippe Ranjeva^3,4, and Virginie Callot^3,4
1CRMBM-CEMEREM UMR 7339, Aix-Marseille Université, CNRS, Marseille, France, ²LBA UMR T 24, Aix-Marseille Université, IFSTTAR, Marseille, France,³CRMBM UMR 7339, Aix-Marseille Université, CNRS, Marseille, France, ⁴CEMEREM, Pole d'imagerie médicale, Hopital la TImone, AP-HM, Marseille, France,⁵Siemens AG, Healthcare, Erlangen, Germany

MRI can provide valuable information about spinal cord (SC) structure. In the current study, we combine multimodal MRI (DTI and inhomogeneous magnetization transfer, ihMT) and atlas-based analysis of the derived parametric data to study: 1) healthy internal SC structural variations (in terms of myelin and axonal content at different levels) and 2) impairment occurring through the lifespan. Thereby, we highlighted vertebral level and sensory/motor tract-specific SC structure dependency, as well as demyelination and axonal loss occurring with age. Altogether, this study also provides a normative DTI and MT/ihMT database metrics at different ages, useful for pathological studies (MS, ALS).

Tanguy Duval¹, Alicja Gasecka^2,3, Philippe Pouliot^1,4, Daniel Côté^2,3, Nikola Stikov^1,5, and Julien Cohen-Adad^1,6
1Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, Qc, Canada, ²Quebec Mental Health University Institute, Québec, Qc, Canada,³Doptic, photonic and laser Center, Université Laval, Québec, Qc, Canada, ⁴Montreal Heart Institute, Montreal, Quebec, Canada, ⁵Montreal Neuronal Institute, McGill University, Montréal, Québec, Canada, ⁶Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montréal, Qc, Canada

Histology is considered to be the gold standard for validating quantitative MRI techniques. However, common histology techniques can induce biases due to the tissue preparation (fixation, cutting and staining), rendering challenging the validation of quantitative MRI biomarkers. Recently, a large-scale microscopy technique called Coherent Anti-Stokes Raman Scattering (CARS) was introduced, enabling (i) sub-micrometer resolution, (ii) in-depth focus preventing artifacts related to non-perfectly flat tissue surface and (iii) specific contrast to myelin without the need for staining. Here we applied the CARS technique to validate AxCaliber experiments for estimating axon diameter measurements.

Torben Schneider¹, Gemma Nejati-Gilani^2,3, Mohamed Tachrount⁴, Ying Li⁵, Amber Hill⁴, Olga Ciccarelli⁴, Ken Smith⁶, David Thomas⁷, Daniel C Alexander³, and Claudia A M Wheeler-Kingshott^1
1NMR Research Unit, Department of Neuroinflammation, Queen Square MS Centre, UCL Institute of Neurology, London, United Kingdom, ²Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom, ³Centre for Medical Image Computing, Department of Computer Science, University College London, London, United Kingdom, ⁴Brain Repair & Rehabilitation, UCL Institute of Neurology, London, United Kingdom, ⁵Spinal Repair Unit, Brain Repair & Rehabilitation, UCL Institute of Neurology, London, United Kingdom, ⁶Department of Neuroinflammation, Queen Square MS Centre, UCL Institute of Neurology, London, United Kingdom, ⁷Leonard Wolfson Experimental Neurology Centre, UCL Institute of Neurology, London, United Kingdom

Diffusion MRI has been applied successfully before to study rodent models of spinal cord damage, but no attempt has been made to try to explicitly model the different pathological effects in the damaged white matter. This study demonstrates the application of a complex diffusion MRI model to early and late axonal injury. We find that axon radius, together with changes in diffusivity and compartmentalisation are discriminating best between early and late stage changes in spinal cord lesion and replicate independent measures of axonal damage in histology.

Damien Jacobs¹, Benoit Scherrer², Aleksandar Jankovski³, Anne des Rieux⁴, Maxime Taquet¹, Bernard Gallez⁴, Simon K. Warfield², and Benoit Macq^1
1ICTEAM, Universite catholique de Louvain, Louvain-La-Neuve, Belgium, ²Computational Radiology Laboratory, Boston Childrens Hospital, Massachusetts, United States, ³Hopital universitaire Mont-Godinne, Universite catholique de Louvain, Godinne, Belgium, ⁴LDRI, Universite catholique de Louvain, Brussels, Belgium

The aim of this study is to investigate the Wallerian degeneration process by DIAMOND, a multi-compartment diffusion model, in the rat spinal cord after a rhizotomy. With a longitudinal imaging approach and several histological observations for each specific cellular response, the fluctuations of the diffusion parameters are analyzed and compared to the Wallerian degeneration process in the course of time.

Peng Sun¹, Rory Murphy², Yong Wang¹, Joanne Wagner³, Sammir Sullivan¹, Paul Gamble², Kim Griffin^1,2, Wilson Z. Ray², and Sheng-Kwei Song^1
1Radiology, Washington University in St. Louis, St. Louis, MO, United States, ²Neurosurgery, Washington University in St. Louis, St. Louis, MO, United States, ³Physical Therapy and Athletic Training, Saint Louis University, St. Louis, MO, United States

Cervical spondylotic myelopathy (CSM) is the most common form of spinal cord injury, but no effective diagnostic approach available to accurately reflect underlying tissue damage. In this study, newly developed diffusion basis spectrum imaging (DBSI) was applied to quantify pathologies in CSM. DBSI successfully delineated axon and myelin injury, quantified the extent of axon loss and edema of CSM spinal cord. Findings suggest that axon loss may be the primary contributor to neurological impairment in CSM. The multiple metrics derived by DBSI, could offer an insight to the underlying pathologies responsible for the evolving neurological impairments in CSM.

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

This study has demonstrated the feasibility of using hyperpolarized ¹³C MR imaging with [1-¹³C]pyruvate for evaluating in vivo metabolism of spinal cord. High pyruvate and relatively small lactate signal were observed in the cervical spinal cord of uninjured rats. The results from this study suggest that this technique may provide a unique non-invasive imaging tool that is able to monitor biochemical processes underlying spinal cord injury.

Mami Iima¹, Akira Yamamoto¹, Denis Le Bihan^2,3, Shigeru Hirano⁴, Ichiro Tateya⁴, Morimasa Kitamura⁴, and Kaori Togashi^1
1Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, Japan, ²Human Brain Research Center, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, Japan, ³Neurospin, CEA-Saclay Center, Gif-sur-Yvette Cedex, France, ⁴Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, Japan

This prospective study included 46 patients suspected of head and neck tumors. They were scanned using a RS-EPI diffusion MRI sequence implemented on a 3T MRI scanner. Images were analyzed with a new approach algorithm which enables automatic classification of tumor types from a "signature index" (S-index) directly based on the non-Gaussian diffusion signal pattern obtained from 2 �gkey b values�h. This computer-assisted diagnostic algorithm allowed malignant and benign lesions to be differentiated with a high AUC (0.89). The lesion S-index histogram and 3D display also highlighted the importance of tumor heterogeneity.

Merry Mani¹, Mathews Jacob², and Vincent Magnotta^3
1Dept of Psychiatry, University of Iowa, Iowa City, IA, United States, ²Dept of Electrical and Computer Engineering, University of Iowa, Iowa City, IA, United States, ³Dept of Radiology, University of Iowa, Iowa City, IA, United States

Brain regions such as pons, cerebellum, spine etc are difficult to image using diffusion imaging due to the presence of air/bone/tissue interfaces causing severe susceptibility artifacts. In addition, cardiac pulsation, respiratory and swallowing motions also adversely affect these regions. We present a high spatial and angular resolution diffusion scheme that can image these regions without being severely corrupted by these artifacts. The proposed method uses a compressed sensing based joint k-q space under-sampling using multi-shot variable density spirals to image these regions. The motion-compensated joint reconstruction can recover diffusion orientation distribution functions at high resolution to enable the study of these regions.

Sajan Goud Lingala¹, Yinghua Zhu¹, Yoon-Chul Kim², Asterios Toutios¹, Shrikanth Narayanan¹, and Krishna S Nayak^1
1Electrical Engineering, University of Southern California, Los Angeles, California, United States, ²Samsung Medical Center, Seoul, Korea

Real time MRI (RT-MRI) is a powerful tool to visualize the complex spatio-temporal coordination of upper airway structures during speech production. In this work, we propose to improve imaging trade-offs in RT-MRI by utilizing (a) a novel upper airway coil which has improved sensitivity in upper airway regions of interest, (b) a flexible slice selective spiral acquisition with golden angle time interleaving, and (c) a temporal constrained reconstruction scheme. With the proposed approach, we show improved depiction of fine articulatory movements (such as production of consonant clusters) by enabling time resolution of 12 msec for single slice imaging, and 36 msec for concurrent three slice imaging.

Jürgen Braun¹, Sebastian Hirsch², Jing Guo², Katharina Erb-Eigner², and Ingolf Sack^2
1Department of Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Berlin, Germany, ²Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany

The feasibility of in vivo MR-elastography (MRE) of human eyes is demonstrated. A clinically applicable actuator for inducing shear waves into the eye was constructed which could be combined with a standard head coil and a specialized eye coil. 3D MRE of 90 and 100 Hz vibration frequency and 1mm^3 cubic voxel resolution was used for reconstructing viscoelastic parameter maps of magnitude and phase angle of the complex shear modulus. We measured a magnitude modulus of 1084  366 Pa in the vitreous body which agrees to in-vivo values obtained in the mouse.