Diffusion, DTI & Tractography: Clinical Studies
Thursday 23 April 2009
Room 311 10:30-12:30

Moderators:

 Derek K. Jones and Joshua S. Shimony
 
10:30 639. White Matter Is Diffusely Affected in Autism
    Andrew L. Alexander1, Jee Eun Lee1, Erin D. Bigler2, Molly B. DuBray2, Alyson Froehlich2, Nicholas Lange3, Thomas P. Fletcher2, Moo K. Chung1, Janet E. Lainhart2
1University of Wisconsin, Madison, WI, USA; 2University of Utah, Salt Lake City, UT, USA; 3Laboratory for Statistical Neuroimaging McLean Hospital, Belmont, MA, USA
    DTI measures were compared between a group of children and young adults with autism versus typically developing controls. Two advanced voxel-based analysis methods – T-SPOON and TBSS – were used for the group comparison study. Spatially diffuse WM differences were observed for FA, mean diffusivity and the third (smallest) eigenvalue, but not the first (largest) eigenvalue. In general, the T-SPOON voxel-based analysis appeared to be more sensitive to group differences than TBSS although both methods found extensive group differences. The specific biological mechanism of the differences in the DTI measures is still unknown; however, they are consistent with recent theories of brain underconnectivity in autism.
     
10:42 640. The Limbic System in Asperger Syndrome: A Preliminary Diffusion Tensor Imaging Tractography Study
    Luca Pugliese1,2, Michel Thiebaut de Scotten1,2, Stephanie Ameis2, Flavio Dell'Acqua1,2, Eileen Daly1, Declan Murphy1, Marco Catani1,2
1Phsychological Medicine, section of Brain Maturation, Institute of Psychiatry, London, UK; 2Natbrainlab, section of Brain Maturation, Institute of Psychiatry, London, UK
   

It has been suggested that people with Autistic Spectrum Disorder (ASD) have altered development (and connectivity) of limbic circuits. However, direct evidence is lacking. We used DTI-tractography to compare, in vivo, tract-specific measurements along the principal limbic pathways between subjects with Asperger syndrome and healthy controls.

Limbic pathways differences were found between Asperger group and controls in the number of streamlines of the cingulum, ILF, and uncinate. The most robust difference was observed in the right cingulum, suggesting a greater involvement of those pathways connecting limbic regions involved in emotion processing and social cognition.
     
10:54 641. 3T Diffusion Tensor Imaging of Mild Traumatic Brain Injury: A Prospective Longitudinal Study
    Joshua Ng1, Michael Wahl1, Elizabeth Tong1, Hana Lee2, Srivathsa Veeraraghavan1, Duan Xu1, Shoujun Zhao1, John Kornak1, Michele Meeker2, Jamshid Ghajar3, Geoffrey T. Manley2, Pratik Mukherjee1
1Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA; 2Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA; 3Brain Trauma Foundation, New York, NY, USA
    With 1.4 million Americans suffering from traumatic brain injury (TBI) each year, the vast majority of which is mild TBI, better diagnosis is needed for treatment planning. In this study, quantitative DTI tractography at 3T detected reduced microstructural integrity of several white matter tracts with prefrontal connectivity in 31 mild TBI patients compared to 19 matched controls. Trends toward decreasing microstructural integrity were identified in almost all investigated white matter tracts between 1 month and 1 year after injury, but these did not reach statistical significance in this initial study.
     
11:06 642. Mapping Traumatic Axonal Injury Using Diffusion Tensor Imaging: Correlations with Functional Outcome
    Virginia F.J. Newcombe1,2, Doris A. Chatfield1,2, Martin R. Coleman3, Joanne G. Outtrim1,2, Sarah Vowler4, Anne Manktelow1,2, Justin Cross5, Sally G. Harding2, Peter JA Hutchinson6, Jonathan P. Coles1,2, T. Adrian Carpenter2, John D. Pickard3,6, Guy B. Williams2, David K. Menon1,3
1Division of Anaesthesia, University of Cambridge, Cambridge, Cambridgeshire, UK; 2Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, Cambridgeshire, UK; 3Cambridge Impaired Consciousness Group, Wolfson Brain Imaging Centre; 4Centre for Applied Medical Statistics, University of Cambridge; 5Department of Radiology, Addenbrookes Hospital; 6Academic Department of Neurosurgery, University of Cambridge
    Traumatic brain injury (TBI) is a major cause of morbidity and mortality. The extent and severity of traumatic axonal injury (TAI) is greatly underestimated by CT and conventional MR sequences, and these appearances often correlate poorly with functional outcome. This study investigated trends in diffusion tensor imaging (DTI) parameters in the central white matter to clinical outcome as defined by the Glasgow Outcome Score (GOS) in a cohort of sixty-one patients with clinical outcomes ranging from the vegetative state (VS) and minimally conscious state (MCS) spectrum (GOS 2) through to good recovery (GOS 5).
     
11:18 643. Optic Radiation Abnormalities After Optic Neuritis
    Scott Cameron Kolbe1,2, Clare Bajraszewski1, Caron Chapman2, Thanh Nguyen3, Leigh Johnston1,4, Peter Mitchell5, Mark Paine3, Helmut Butzkueven1,2, Trevor Kilpatrick1,2, Gary Egan1,2
1Florey Neuroscience Institutes, Melbourne, Victoria, Australia; 2Centre for Neuroscience, University of Melbourne, Melbourne, Victoria, Australia; 3Neuro-ophthalmology Unit, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia; 4Department of Electrical and Electronic Engineering, University of Melbourne, Melbourne, Victoria, Australia; 5Department of Radiology, Royal Melbourne Hospital, Melbourne, Victoria, Australia
    We studied optic radiation DTI and multifocal visual evoked potentials in 15 patients with a history of optic neuritis, a common presentation of Multiple Sclerosis (MS). We found significant abnormalities in patient normal-appearing white matter in the optic radiations. We also found that reduced axial diffusivity in NAWM was associated with visual dysfunction in the affected eye indicative of optic nerve axonal pathology. These results suggest that trans-synaptic degeneration contributes to NAWM abnormalities in the context of MS.
     
11:30 644. Multimodality Study for Restless Legs Syndrome: Morphological Changes in White and Gray Matter
    Byeong-Yeul Lee1, Don Bigler1, James R. Connor2, Qing X. Yang1,3
1Bioengineering, The Penn State University, Hershey, PA, USA; 2Neurosurgery, The Penn State University, Hershey, PA, USA; 3Radiology, The Penn State University, Hershey, PA, USA
    Restless legs syndrome (RLS) is a sensory-motor disorder causing chronic sleep disturbance. Our goal was to investigate overall morphological changes with voxel-based morphometry (VBM) and white matter changes with diffusion tensor imaging (DTI) in RLS. Our results showed that a significant decrease of volume and FA in gray/white matter of RLS compared to the controls, demonstrating intrinsic pathological changes occurring in RLS brain. Fusion of the two imaging modalities is valuable clinically for diagnosis and monitoring RLS and scientifically for elucidating the disease mechanism.
     
11:42 645. Diffusion Tensor Imaging of Remaining Brain After Long Term Hemispherectomy
    Andreia Vasconcellos Faria1,2, Julia Choi1, Eileen Patti Vining1, Jiangyang Zhang1, Kenishi Oishi1, Xin Li3, Hangyi Jiang1, Kazi Akhter1, Peter van Zijl1,3, Michael I. Miller4, Amy Bastian1,3, Susumu Mori1
1Johns Hopkins Medical Institutes, Baltimore, MD, USA; 2State University of Campinas, Campinas, SP, Brazil; 3Kennedy Krieger Institute, Baltimore, MD, USA; 4Center for Imaging Studies, Johns Hopkins Medical Institutes, Baltimore, MD, USA
    We investigated the remaining brain architecture of hemispherectomy patients using Diffusion Tensor Images (DTI) that provide suitable intra-white matter contrast. Using a nonlinear warping algorithm based on large deformation, diffeomorphic metric mapping (LDDMM) we registered participants into common coordinates. The recently established brain atlas was used to automatically segment the brains which enabled us to investigate differences in individual regions. This method clearly identified areas of Wallerian degeneration in white matter and detected increased FA in gray matter structures. Unexpected results included the lack of FA abnormalities in the medial lemniscii and "fiber mixing areas" in the corona radiata.
     
11:54 646. In Vivo Definition of Parieto-Motor Pathways During Movement Planning Using Twin-Coil TMS and DT-MRI Based Tractography
    Mara Cercignani1, Giacomo Koch2,3, Carlo Caltagirone2,3, Marco Bozzali1
1Neuroimaging Laboratory, Fondazione Santa Lucia, Roma, Italy; 2Dept of Clinical and Behavioural Neurology, Fondazione Santa Lucia, Roma, Italy; 3Dept of Neuroscience, University of Rome 'Tor Vergata', Roma, Italy
    We used a 'paired-pulse' transcranial stimulation (TMS) paradigm to study functional 'connections' between posterior parietal cortex (PPC) and ipsilateral motor cortex in ten healthy volunteers while planning either a whole hand grasp or a precision grip of an object. The superior longitudinal fasciculus (SLF) of every subject was reconstructed using probabilistic tractography. Facilitation due to the cortical stimulation over the PPC became evident when subjects planned a lateralized grasp, and the relative increase was correlated with the mean fractional anisotropy of the SLF, suggesting that this information is effectively mediated by this white matter pathway.
     
12:06 647. Connective Fiber Tracts in Default Mode Network Mapped by Resting State FMRI and Diffusion Spectrum Imaging
    Su-Chun Huang1, Fang-Chen Yeh2, Wei-Tang Chang3, Fa-Hsuan Lin3, Wen-Yih Isaac Tseng1,2
1Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; 2Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan; 3Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
    The study used diffusion spectrum imaging (DSI) tractography, with the locations of cortical regions of default mode network (DMN) provided by resting-state fMRI, to map out the complete connective fiber structures of the whole DMN in human brain. The results showed that medial prefrontal cortex (MPFC) and posterior cingulated cortex/ retrosplenial cortex (PCC/RSC) were connected by cingulum bundles. PCC/RSC and medial temporal lobe (MTL) were connected by inferior longitudinal fasciculus and inferior fronto-occipital fasciculus. Bilateral MTLs were connected by tapetum of corpus callosum. The MPFC and bilateral MTLs were connected by stria terminalis and medial forebrain bundle. Tract between bilateral PCC/RSC is splenium of corpus callosum and tract between bilateral MPFC is genu of corpus callosum. These tracts were found to involve the limbic system pathways on each hemisphere and commissural fibers connecting bilateral hemispheres.
     
12:18 648. Topographic Organization of SMA Connections as Assessed by MR DTI Tractography and Intraoperative Subcortical Mapping
    Antonella Castellano1,2, Lorenzo Bello3, Paola Scifo4, Enrica Fava3, Giorgio Carrabba3, Giulio Bertani3, Giuseppe Scotti1, Andrea Falini1
1Neuroradiology Unit and CERMAC, Scientific Institute and University Vita-Salute San Raffaele, Milan, MI, Italy; 2Institute of Radiological Sciences, University of Milano, Milan, MI, Italy; 3Neurosurgery, Department of Neurological Sciences, University of Milano, Milan, MI, Italy; 4Nuclear Medicine Department, San Raffaele Scientific Institute, Milan, MI, Italy
    Supplementary motor area (SMA) is a crucial cerebral region involved in the temporal organization of motor tasks, especially in sequential performance of multiple movements. Purpose of this study was to explore functional connections of SMA proper by the means of intraoperative subcortical mapping and DTI tractography in patients with cerebral gliomas; data from stimulation were retrospectively used to define anatomical regions of interest for tractography segmentation of subcortical connections of SMA.