High Resolution Brain Imaging
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Monday May 9th
Room 511A-C  11:00 - 13:00 Moderators: Fernando Calamante and Timothy Q. Duong

11:00 4.   Using in-vivo MRI to study learning induced brain plasticity in adult mice trained on a spatial maze.  
Jurgen Germann1, D. Vousden1, P Steadman1, J. Dazai1, C. Laliberte1, S. Spring1, L. Cahill1, R. M. Henkelman1, and Jason P Lerch1
1The Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada

 
Brain shape is influenced by experience. The time course of the changes, however, remains unknown. In our study we longitudinally imaged mice undergoing spatial navigation training. Our results show that learning is associated with definite local brain changes detectable using live-imaging. These changes, found as early as on the second day of training, occur in specific brain regions depending on the experimental setup. The time course of local remodeling varies between regions. Whole brain live MRI is capable of detecting and characterizing these brain changes and is instrumental studying local changes within the brain as a learning system.

 
11:12 5.   Can preexisting differences in neuroanatomy predict training performance? An in-vivo MRI study of adult mice trained on a spatial maze.  
Jurgen Germann1, P. Steadman1, D. Vousden1, J. Dazai1, S. Spring1, C. Laliberte1, L. Cahill1, R. M. Henkelman1, and J. P. Lerch1
1The Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada

 
The famous London taxi driver study demonstrated that some hippocampal regions are larger in taxi drivers compared to matched controls. These anatomical differences are likely related to extensive experience. What, however, is the influence of preexisting anatomical differences on subsequent learning performance. In our study we imaged mice prior to spatial navigation training. Our results show that local variance in brain shape predicts subsequent learning performance. The relevant regions differ depending on the learning condition. Whole brain live MRI is capable of detecting and characterizing preexisting anatomical differences and instrumental in studying brain behavior relationship.

 
11:24 6.   Super-resolution track-density imaging studies of mouse brain: comparison to histology  
Fernando Calamante1,2, Jacques-Donald Tournier1,2, Nyoman D Kurniawan3, Zhengyi Yang3, Erika Gyengesi4, Graham J Galloway3, David C Reutens3, and Alan Connelly1,2
1Brain Research Institute, Florey Neuroscience Institutes, Heidelberg West, Victoria, Australia, 2Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia, 3Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland, Australia, 4Neuroscience Research Australia, Randwick, New South Wales, Australia

 
The recently introduced super-resolution track-density imaging (TDI) is able to increase the spatial resolution of the reconstructed images beyond the acquired MRI resolution by incorporating information contained in whole-brain fibre-track modelling results. The TDI technique not only provides a means to achieve super-resolution, but it also provides very high anatomical contrast with a new MRI contrast mechanism. However, the anatomical information-content of this novel contrast mechanism has not been validated yet. We perform such a study using ex vivo mouse brains acquired at 16.4T, and comparing the results of the super-resolution TDI technique to histological staining.

 
11:36 7.   Ultra high resolution functional MRI and electrophysiology of the rat primary somatosensory cortex  
Yen-Yu Ian Shih1, You-Yin Chen2, Hsin-Yi Lai2, and Timothy Q Duong1
1Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States, 2Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan

 
This study employed very high resolution CBV fMRI (40x40 ým in-plane resolution) and multichannel field potential recording to investigate the neurovascular coupling within cortical laminae. This MRI resolution was achieved by using a small surface coil and an 11.7 T scanner. Graded forepaw electrical stimulation was employed to modulate layer-specific neuronal activities. Our results indicate that CBV responses and field potential changes at laminar resolution are not completely coupled.

 
11:48 8.   Magnetic Resonance Microscopy of Human lower case Greek alpha-Motor Neurons and Neural Processes  
Jeremy Joseph Flint1,2, Brian Hansen3, Sharon Portnoy1,2, Choong H Lee2,4, Michael A King5, Michael Fey6, Franck Vincent6, Peter Vestergaard-Poulsen3, and Stephen J. Blackband2,7
1Neuroscience, University of Florida, Gainesville, Fl, United States, 2McKnight Brain Institute, University of Florida, Gainesville, Fl, United States, 3Center for Functionally Integrative Neuroscience, University of Aarhus, Aarhus, Denmark, 4Electrical Engineering, University of Florida, Gainesville, Fl, United States, 5Pharmacology and Therapeutics, University of Florida, Gainesville, Fl, United States, 6Bruker Biospin, 7National High Magnetic Field Laboratory, Talahassee, Fl, United States

 
The ability to resolve microstructural details of biological tissues has been a long sought-after goal in the field of MR imaging. Magnetic resonance microscopy (MRM) has evolved to reveal ever-finer details of the cellular organization which makes up tissue parenchyma. Such techniques are needed so that we may understand the primary structural origins underlying MR signal changes resultant from pathology. In the current study, we report what we believe to be the first instances of cellular imaging in humans and neural process imaging in humans and pigs using magnetic resonance microscopy techniques.

 
12:00 9.   Evidence towards columnar organization of human area MT with sub-millimetric, 3D, T2 weighted BOLD fMRI at 7 Tesla 
Federico De Martino1, Jan Zimmermann1, Gregor Adriany2, Pierre-Francois van de Moortele2, David A Feinberg3, Kamil Ugurbil2, Rainer Goebel1, and Essa Yacoub2
1Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands, 2CMRR, Radiology, University of Minnesota, Minneapolis, Minnesota, United States, 3Advanced MRI Technologies, Sebastopol, California, United States

 
We provide direct evidence of columnar organization of direction selective features (DSF) in human area MT using spin echo BOLD based fMRI at ultra high fields (7 tesla). We demonstrate that the functional selectivity and sensitivity of high field high resolution SE BOLD fMRI is sufficient to resolve the fine grained organization of feature representations within higher level folded cortical areas.

 
12:12 10.   Within digit somatotopy of the human somatosensory cortex using fMRI at 7T  
Rosa M Sanchez Panchuelo1, Julien Besle2, Richard Bowtell1, Denis Schluppeck2, and Susan Francis1
1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, United Kingdom, 2School of Psychology, University of Nottingham, Nottingham, United Kingdom

 
The increased BOLD contrast-to-noise ratio at 7T has been exploited to measure fine topographic organisation in individual subjects within the index finger representation (base-to-tip) in human somatosensory cortex (S1) at 1.5mm isotropic resolution using a travelling wave paradigm. Subjects were scanned twice to assess reproducibility, and data displayed on a flattened representation of the cortex. An organized somatotopy within the cortical area corresponding to the index finger was found for two subjects, with phase reversals in the map which are consistent with mirrored representations in adjacent sub-regions 3a/3b/1/2 of S1. The results were reproducible across sessions for all subjects.

 
12:24 11.   Fast high resolution whole brain T2* weighted imaging using echo planar imaging at 7T  
Jaco J.M. Zwanenburg1,2, Maarten J Versluis3, Peter R Luijten1, and Natalia Petridou1,4
1Radiology, Universiy Medical Center Utrecht, Utrecht, Netherlands, 2Image Sciences Institute, Universiy Medical Center Utrecht, Utrecht, Netherlands, 3Radiology, Leiden University Medical Center, Leiden, Netherlands, 4Rudolf Magnus Institute, University Medical Center Utrecht, Utrecht, Netherlands

 
This work shows that high resolution (0.5 mm isotropic) T2* weighted images of the whole brain can be obtained in less than 6 minutes by utilizing the high SNR efficiency of echo planar imaging (EPI). The image SNR is increased by a factor of 2, and the coverage by a factor of approx. 5, compared to conventional gradient echo imaging (GRE) with the same scan duration. The contrast for both magnitude and phase is equivalent between EPI and GRE imaging.

 
12:36 12.   Investigation of magnetic susceptibility contrast across cortical grey matter and white matter  
Masaki Fukunaga1,2, Peter van Gelderen1, Jongho Lee1, Tie-Qiang Li1, Jacco A de Zwart1, Hellmut Merkle1, Kant M Matsuda3, Eiji Matsuura4, and Jeff H Duyn1
1Advanced MRI section, LFMI, NINDS, National Institutes of Health, Bethesda, MD, United States, 2Biofunctional Imaging, Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan, 3Laboratory of Pathology, NCI, National Institutes of Health, Bethesda, MD, United States, 4Laboratory of Neuroimmunology, NINDS, National Institutes of Health, Bethesda, MD, United States

 
Variations of magnetic susceptibility have been demonstrated in primary visual cortex and shown to relate to tissue iron content. Here we extend this finding to cortical regions in the parietal lobe of human brain. Comparison of 7T MRI data with iron and myelin histology suggests that iron dominates the contrast across many cortical areas including sensory-motor cortex, cingulate and precuneus. Interestingly, myelin and iron differentially contribute to susceptibility contrast in subcortical white matter versus the optic radiation.

 
12:48 13.   Exploring Orientation Dependence of T2* in White Matter by Extreme Rotation of the Human Head at 7 Tesla  
Graham Wiggins1, Chris Wiggins2, Bei Zhang1, Ryan Brown1, Bernd Stoeckel3, and Daniel K Sodickson1
1Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY10016, United States, 2CEA/NeuroSpin, Saclay, France,3Siemens Medical Solutions USA Inc, New York, NY, United States

 
At 7T, T2* weighted gradient echo imaging reveals unexpected contrast variation in white matter which appears to be associated with specific fiber bundles. The mechanism behind this variation has been debated, and it has been proposed that it may be caused by intrinsic properties of the fiber bundle such as degree of myelination or iron content, or that it depends on the orientation of the fiber bundles in relation to the main B0 field. With a novel coil system we obtain T2* maps in orientations 90 degrees apart and demonstrate that T2* depends strongly on orientation.