Diffusion Applications

Monday 12 May 2014

Martyn Ezra¹, Olivia Kate Faull¹, Saad Jbabdi², and Kyle Thomas Shane Pattinson^1
1Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, Oxfordshire, United Kingdom, ²Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, University of Oxford, Oxford, Oxfordshire, United Kingdom

The periaqueductal gray matter (PAG) is involved in a number of key neurobiological functions. Animal research has identified four sub-divisional columns that differ in both connectivity and function. This study used high-resolution diffusion tensor imaging and probabilistic tractography to segment the human PAG based upon voxel connectivity profiles. While we identified four distinct subdivisions demonstrating spatial concordance with the columns of the animal model, the connectivity profiles of these subdivisions were different to those in animals. This is the first study to resolve subdivisions within the human PAG, and may aid stereotactic interventions and interpretation of functional imaging studies.

Marta Bianciardi¹, Nicola Toschi^1,2, Cornelius Eichner¹, Kawin Setsompop¹, Florian Beissner¹, Vitaly Napadow¹, Jonathan R Polimeni¹, and Lawrence L Wald^1
1Department of Radiology, A.A. Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Boston, MA, United States, ²Department of Medicine, University of Rome “Tor Vergata”, Rome, Italy

The human brainstem plays an important role in several vital functions, including sleep, and respiration. Our current knowledge of gray matter (GM) structure within the brainstem mostly derives from ex-vivo studies. Aim of this work was to develop novel in-vivo MRI-tools to identify GM-structure. We employed in-vivo high spatial-resolution DTI at 7Tesla, and scrutinized the contrast in DTI-maps, including fractional-anisotropy (FA). In single subject FA-maps, major clusters of brainstem-nuclei were visible with high contrast including the median-raphe-nucleus, the reticular-formation, and the vestibular/olivary/pontine nuclei. High-resolution DTI is a promising tool to delineate GM-structure in the brainstem in-vivo on a subject-by-subject basis.

Kaikai Shen¹, Stephen Rose¹, Jurgen Fripp¹, Katie McMahon², Greig de Zubicaray³, Nicholas Martin⁴, Paul Thompson⁵, Margaret Wright⁴, and Olivier Salvado^1
1Australian e-Health Research Centre, CSIRO, Herston, Queensland, Australia, ²Centre for Advanced Imaging, University of Queensland, St Lucia, Queensland, Australia, ³School of Psychology, University of Queensland, St Lucia, Queensland, Australia, ⁴Queensland Institute of Medical Research, Herston, Queensland, Australia, ⁵Imaging Genetics Centre, University of Southern California, Los Angeles, California, United States

We aim to estimate the genetic influence on WM structures using Fibre Orientation Distrubution (FOD) based measurements. We hypothesize that because FOD resolves the crossing fibres, it will allow measuring genetic influence on intra-voxel fibre structures. We estimated the heritability of FOD measures over a twin cohort, by projecting the heritability of FOD onto fibre tracks, and estimating the genetic influence along fibre tracks.

Longchuan Li¹, Xiaoping Hu², Jocelyne Bachevalier³, Warren Jones¹, Sarah Shultz¹, and Ami Klin^1
1Department of Pediatrics, Marcus Autism Center, Children's HealthCare of Atlanta, Emory University, Atlanta, GA, United States, ²Department of Biomedical Engineering, Emory University School of Medicine, Atlanta, GA, United States, ³Yerkes National Primate Research, Emory University, GA, United States

Amygdala-cortical connections consist of major regions of “social brain” and mapping such a network may be critically informative of its roles in autism. In this study, diffusion tractography was used to delineate the connections between the amygdala and the prefrontal areas in macaque monkeys and humans. The results in monkeys were compared with the tracer literature and were also compared with those in humans. We found a generally similar pattern of connections between the tracer and tractography studies and between two species. Such work serves as the first step in realistically mapping amygdala network for the neural underpinnings of autism.

Matthew Grech-Sollars¹, Patrick W Hales¹, Keiko Miyazaki², Felix Raschke³, Daniel Rodriguez^4,5, Martin Wilson⁶, Simrandip K Gill⁶, Tina Banks⁷, Dawn E Saunders⁷, Jonathan D Clayden¹, Matt Gwilliam², Thomas R Barrick³, Paul S Morgan^4,5, Nigel P Davies⁸, James Rossiter⁹, Dorothee P Auer^4,5, Richard Grundy⁵, Martin O Leach², Franklyn A Howe³, Andrew C Peet⁶, and Chris A Clark^1
1UCL Institute of Child Health, University College London, London, London, United Kingdom, ²CR UK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden Foundation Trust, Surrey, United Kingdom, ³Division of Clinical Sciences, St George's, University of London, London, United Kingdom, ⁴Division of Clinical Neuroscience, University of Nottingham, Nottingham, United Kingdom, ⁵The Children‘s Brain Tumour Research Centre, University of Nottingham, Nottingham, United Kingdom, ⁶School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom,⁷Department of Radiology, Great Ormond Street Hospital for Children, London, United Kingdom, ⁸Imaging and Medical Physics, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom, ⁹Electrical & Computer Engineering, University of Birmingham, Birmingham, United Kingdom

The reproducibility of diffusion MRI parameters, and more specifically the apparent diffusion coefficient (ADC), intra-voxel incoherent motion (IVIM) parameters – the diffusion coefficient (D) and perfusion fraction (f), and diffusion tensor imaging (DTI) parameters – mean diffusivity (MD) and fractional anisotropy (FA), was analysed across multiple centres using standard clinical protocols. ADC, D, MD and FA were found to have a good reproducibility and research studies can benefit from incorporating multi-centre data without any loss of reproducibility compared to what would be achieved from a single scanner at a single site.

Giovanni Giulietti¹, Barbara Spano'¹, Mara Cercignani², Barbara Basile¹, Carlo Caltagirone^3,4, and Marco Bozzali^1
1Neuroimaging Laboratory, Santa Lucia Foundation, Rome, Italy, ²Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom, ³Clinical and Behavioural Neurology, Santa Lucia Foundation, Rome, Italy, ⁴Departement of Neuroscience, University of Rome "Tor Vergata", Rome, Italy

In the current study we compared the results obtained repeating twice the same FSL-TBSS analyses on the fractional anisotropy (FA) maps, belonging to patients with relapsing remitting multiple sclerosis and healthy subjects, only changing the spatial normalization algorithms. In particular, we tested the differences in using a cubic B-splines (FNIRT, used as default in FSL) and a diffeomorphic (ANTs) transformations algorithms, in terms of the produced skeleton layout and the results of the statistical group comparison. We found that the TBSS-ANTs analysis was able to reconstruct more WM tracts and to detect FA group differences in more brain regions.

Gavin P Winston¹, Pankaj Daga², Mark J White^3,4, Caroline Micallef^3,4, Anna Miserocchi⁵, Laura Mancini^3,4, Marc Modat², Jason Stretton¹, Meneka K Sidhu¹, Mark R Symms¹, David J Lythgoe⁶, John Thornton^3,4, Tarek A Yousry^3,4, Sebastien Ourselin², John S Duncan¹, and Andrew W McEvoy^5
1Epilepsy Society MRI Unit, Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, England, United Kingdom, ²UCL Centre for Medical Image Computing, London, United Kingdom, ³Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, London, United Kingdom, ⁴Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, United Kingdom, ⁵Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom, ⁶Centre for Neuroimaging Sciences, Institute of Psychiatry, Kings College London, England, United Kingdom

Anterior temporal lobe resection (ATLR) for refractory epilepsy may cause a visual field deficit (VFD) that precludes driving. We studied 21 patients undergoing ATLR in an intraoperative MRI (iMRI) suite. Preoperative tractography of optic radiation was displayed on the navigation and operating microscope displays either without (9 patients) or with (12 patients) correction for brain shift. Display of the optic radiation during surgery significantly reduced the degree of VFD and no patient developed a VFD that precluded driving (compared to 13% of a historical non-iMRI cohort). Outcome did not differ between iMRI guidance with and without brain shift correction.

Manzar Ashtari¹, Gary Hui Zhang², Laura Cyckowski¹, Philip Cook³, Amanda Viands¹, Kathleen Marshall⁴, James Gee³, Albert Maguire⁵, and Jean Bennett^6
1Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, United States, ²Computer Science, University College London, London, United Kingdom,³Radiology, University of Pennsylvania, Philadelphia, PA, United States, ⁴CCMT, Children's Hospital of Philadelphia, Philadelphia, PA, United States,⁵Ophthalmology, University of Pennsylvania, PA, United States, ⁶Ophthalmology, University of Pennsylvania, Philadelphia, PA, United States

Visual deprivation and blindness are debilitating disorders with no available treatment. Recently, retinal gene therapy has successfully treated a group of patients with Leber's congenital amaurosis (LCA) and has profoundly affected the quality of their lives. Of all sensory systems, vision provides the most information to the brain and plays a central role in how we relate to and interact with the world. Thus, the success of this exciting treatment raises the question of the effect this therapy may have on the brain’s visual pathways. We have employed advanced functional and structural imaging to answer this question.

Wieke Haakma^1,2, Pieter Dik³, Bennie ten Haken⁴, Martijn Froeling¹, Rutger Jan Nievelstein¹, Jeroen Hendrikse¹, Inge Cuppen⁵, Tom de Jong³, and Alexander Leemans^6
1Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, ²Department of Forensic Sciences and Comparative Medicine Lab, Aarhus University, Aarhus, Central Denmark, Denmark, ³Pediatric Urology, University Medical Center Utrecht, Utrecht, Netherlands, ⁴Institute for Biomedical Technology & Technical Medicine, University of Twente, enschede, Overijssel, Netherlands, ⁵Pediatric Neurology, University Medical Center Utrecht, Utrecht, Netherlands, ⁶Image Science Institute, University Medical Center Utrecht, Utrecht, Netherlands

It is still largely unknown how neural tube defects in spina bifida (SB) affect the nerves at the level of the sacral plexus. Visualizing the sacral plexus in 3D could improve anatomical understanding regarding neurological problems. 10 SB patients underwent DTI on a 3 Tesla MRI. With tractography the microstructural properties of the nerves were investigated and were compared with 10 healthy controls. The sacral plexus of SB patients showed asymmetry, disorganization and lower diffusion values compared to healthy controls. We expect that this technology can provide a valuable contribution to a better analysis of these patients in the future.

Marianne J U Novak^1,2, Kiran K Seunarine³, Clare R Gibbard^2,3, Bogdan Draganski^4,5, Karl Friston¹, Sarah J Tabrizi^2,6, and Christopher A Clark^3
1Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, London, United Kingdom, ²Department of Neurodegenerative Disease, UCL Institute of Neurology, London, United Kingdom, ³Imaging and Biophysics, UCL Institute of Child Health, London, United Kingdom, ⁴LREN, Département des Neurosciences Cliniques, Université de Lausanne, Switzerland, ⁵Max-Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany,⁶National Hospital for Neurology and Neurosurgery, London, United Kingdom

Huntington's disease (HD) is a genetic condition that affects both the white and grey matter of the brain. Striatal volume loss is the earliest and most characteristic structural abnormality seen using brain imaging in HD. In this work we present a statistical approach that allows us to quantitatively compare connectivity patterns of subcortical nuclei between groups. We apply our technique to a Huntington's disease cohort and find structured differences in patterns of connectivity compared to healthy controls. Conversely, we see no significant differences between premanifest HD patients and controls, which suggests progressive changes to patterns of connectivity with disease progression.