High Resolution Brain Anatomy & Physiology
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Wednesday 9 May 2012
Room 201  13:30 - 15:30 Moderators: Jens Frahm, E. Mark Haacke

13:30 0418.   In vivo visualization of cerebral microvasculature using BOLD contrast microscopic MRA
Sheng-Hsiou Hsu1, Chien-Hsiang Huang1,2, Tiing-Yee Siow1, Yi-Hua Hsu1, Chiao-Chi V. Chen1, and Chen Chang1
1Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, 2Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan

Current magnetic resonance angiography (MRA) methods offer techniques for imaging large vessels but have limited values in the imaging of smaller vessels such as arterioles and venules. 3D £GR2 microscopic magnetic resonance angiography (3D £GR2 mMRA), utilizes the administration of iron oxide contrast agent to visualize microvasculature. However, the complications associated with the use of the contrast agent limit the application of the method in the clinical settings. In this study, we proposed a new 3D gas challenge £GR2* mMRA (3D gas £GR2* mMRA) method that used intrinsic BOLD contrast manipulated by carbogen challenge to directly visualize cerebral microvasculature.

13:42 0419.   
Correlation of T2* and susceptibility mapping with histochemistry in the SN
Anna I. Blazejewska1, Samuel Wharton2, James Lowe3, Dorothee P. Auer4, Nin Bajaj5, Richard W. Bowtell2, and Penny A. Gowland2
1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom, 2Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, 3Division of Pathology, Nottingham University Hospitals NHS Trust, 4Division of Academic Radiology, University of Nottingham, 5Division of Neurology, Nottingham University Hospitals NHS Trust

Death of neuromelanin containing dopaminergic neurones in the substantia nigra accompanied by iron accumulation is a pathological hallmark of Parkinson’s disease (PD). Iron and neuromelanin are best identified histochemically in post mortem (PM) tissue. In this study we show that high resolution images and susceptibility maps acquired post mortem at 7T can be used to distinguish iron and neuromelanin in the SN. Overlap between the TH positive region and segmented neuromelanin confirmed robustness of the registration method and validity of the results. This will assist in interpretation of in vivo results.

13:54 0420.   T2 versus T2* contrast: Strong differences in MRI of cortical layers in living mice
Susann Boretius1,2, Roland Tammer1,3, and Jens Frahm1,3
1Biomedizinische NMR Forschungs GmbH, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany, 2Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany, 3DFG Center of Molecular Physiology of the Brain (CMPB), Göttingen, Germany

Application of genetically modified mice generates an increasing demand for in vivo detection of the fine-structure of the brain. While optimized T2-weighted MRI demonstrated 5 layer-like cerebral microstructures in living mice, this work shows that T2*-weighted MRI did not reveal that kind of cortical fine-structure. However, in the cerebellum, the myelinated white matter could be better distinguished from the granular layer on T2*-weighted images. These results suggest that, in contrast to humans, iron and myelin may not be the predominant sources of cortical gray matter contrast in mice.

14:06 0421.   High spatial resolution susceptibility weighted fast spin echo brain imaging at 3.0 T and 7.0 T
Elena Maria Tovar Martinez1, Fabian Hezel1, Katharina Maria Fuchs1, Jens Wuerfel2,3, Friedemann Paul2,4, Jan Sobesky2, and Thoralf Niendorf1,5
1Berlin Ultra-High Field Facility (B.U.F.F.), Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany, 2Charité University Medicine, Berlin, Germany,3University of Luebeck, Luebeck, Schleswig-Holstein, Germany, 4NeuroCure Clinical Research Center, Berlin, Germany, 5Experimental and Clinical Research Center (ECRC), Charité - University Medicine Campus Berlin Buch, Berlin, Germany

SWI is a technique that utilizes the magnetic susceptibility differences between tissues to highlight small blood vessels. Its clinical use for high spatial resolution is challenged by scan time. This work proposes the use of a displaced UFLARE for susceptibility weighted imaging that affords high spatial resolution and scan time reduction. UFLARE acquires a train of refocused echoes that are independently phase encoded. SWI contrast is accomplished by using an extra evolution time between the initial excitation pulse and the first refocusing pulse. Its applicability for high spatial resolution was examined in volunteer studies at a 3.0 and 7.0 T

14:18 0422.   
B0-orientation dependence can characterize cortical and sub-cortical fibers in vivo at 7T
Julien Cohen-Adad1, Jonathan R Polimeni1, Bruce R Rosen1, Caterina Mainero1, and Lawrence L Wald1,2
1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, 2Harvard-MIT Division of Health Sciences and Technology, MIT, Cambridge, MA, United States

Recent studies have shown a dependency between T2* and orientation of white matter fibers with respect to the orientation of the main magnetic field B0. Here we demonstrate from in vivo T2* mapping at 7T data that B0-orientation dependence can probe the coherency and orientation of cortical fibers, shedding light into the potential use of this type of contrast to characterize cyto-/myeloarchitecture in vivo. The B0-orientation dependence of sub-cortical fibers revealed consistent anatomical features, reflecting U-fibers running tangentially to the sulci and penetrating radially in both contiguous gyri.

14:30 0423.   
Increasing the resolution of diffusion-weighted MRI with distortion compensated orthogonal acquisitions and super-resolution reconstruction
Benoit Scherrer1, Ali Gholipour1, and Simon K. Warfield1
1Radiology, Harvard Medical School, Boston, MA, United States

Increasing the spatial resolution in DW-imaging requires sampling of higher frequencies in k-space which is very challenging with a single shot EPI acquisition. We propose to reduce the spatial encoding burden by employing distortion-compensated orthogonal anisotropic acquisitions, and by achieving super-resolution reconstruction (SRR) of the underlying high-resolution image. We demonstrate that our approach provides better results than acquisition of a single isotropic scan for the same acquisition duration time. This work provides for the first time evidence that SRR, which employs conventional single-shot EPI techniques, may enable resolution enhancement in DWI, and may dramatically impact the way to achieve DW-imaging.

14:42 0424.   Improved subthalamic nucleus visualization using quantitative susceptibility imaging
Sarah Eskreis-Winkler1,2, Tian Liu3, Weiwei Chen4, Michael Kaplitt1, A. John Tsiouris1, and Yi Wang1
1Weill Medical College of Cornell University, New York, NY, United States, 2New York Hospital Queens, Flushing, NY, United States, 3MedImageMetric LLC, 4Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China

Neurosurgeons performing deep brain stimulation on Parkinson’s disease patients must pintpoint the precise location of the subthalamic nucleus -- however this is often difficult to do on T2* and T2 weighted imaging. Here we evaluate the ability of quantitative susceptibility mapping (QSM), a recently developed MR imaging technique, to better locate the STN than T2*W and T2W imaging. We find that QSM provides a better contrast-to-noise ratio (a 6-fold improvement over T2*W, and an 8-fold improvement over T2W) for depicting the STN than conventional MR imaging.

14:54 0425.   Visualization of the human basal ganglia and thalamic circuits in individuals using 7T MRI
Christophe Lenglet1, Aviva Abosch2, Essa Yacoub1, Federico De Martino3, Guillermo Sapiro4, and Noam Harel1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, 2Department of Neurosurgery, University of Minnesota, Minneapolis, MN, United States, 3Department of Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands, 4Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States

Basal ganglia circuits are affected in neurological disorders such as Parkinson’s disease, essential tremor, dystonia and Tourette syndrome. Subject-specific models of the structural and functional connectivity of these circuits are critical for elucidating the mechanisms of these disorders, and developing new treatments. We present a unique ultra-high-field (7T) MRI and computational protocol designed to generate a comprehensive in vivo model of the structure and connections of the human basal ganglia. Our findings open new avenues of investigation into the movement and neuropsychiatric disorders, in individual human subjects.

15:06 0426.   
Effects of metabolic risk factors in Type 2 Diabetes and Hypertension on cortical thickness in the brain
Ekaterina Tchistiakova1,2, Carol E. Greenwood3,4, Nicole D. Anderson3,5, and Bradley J MacIntosh1,2
1Medical Biophysics, University of Toronto, Toronto, ON, Canada, 2Heart and Stroke Foundation Centre for Stroke Recovery, Sunnybrook Research Institute, Toronto, ON, Canada, 3Rotman Research Institute, Baycrest, Toronto, ON, 4Nutritional Sciences, Faculty of Medicine, University of Toronto,5Department of Medicine (Psychiatry) and Psychology, University of Toronto

Type 2 Diabetes Mellitus (T2DM) is associated with global and regional brain tissue atrophy as well as cognitive decline. In this study we examine the effects that physiological factors like blood glucose levels may have on the brain, as measured by cortical thickness. Our analyses indicate there is a significant correlation between fasting glucose and cortical thickness even among individuals that have subclinical fasting glucose levels. Regions showing the strongest association included bilateral superior temporal regions. Our findings suggest that regionalized atrophy in diabetic patients may be detectable prior to T2DM diagnosis, in brain regions that are implicated in dementias.

15:18 0427.   Smaller subcortical volumes in patients with idiopathic generalised epilepsy and their first degree relatives using FIRST analysis
Fahmida A Chowdhury1, Ruth L O'Gorman2, Jonathan O' Muircheartaigh1, Mark P Richardson1, and Gareth J Barker3
1Department of Clinical Neuroscience, Institute of Psychiatry, KCL, London, United Kingdom, 2Center for MR Research, University Children's Hospital, Zurich, Switzerland, 3Department of Neuroimaging, Institute of Psychiatry, KCL, London, United Kingdom

Idiopathic generalised epilepsies have a complex genetic inheritance pattern. Previous studies using quantitative MRI have shown reduced volume of subcortical nuclei in patients with idiopathic generalised epilepsy. In this study we report reduced volumes of thalamus and caudate in both patients with idiopathic generalised epilepsy and their first degree relatives using FIRST, an automated model based segmentation/ registration tool. This data supports that reduced subcortical volumes are heritable imaging endophenotypes for idiopathic generalised epilepsy. This adds to our understanding of the pathophysiology of epilepsy and has the potential to aid future genetic studies.