Measuring consciousness in coma and related states Carol Di Perri, Aurore Thibaut, Lizette Heine, Andrea Soddu, Athena Demertzi, Steven Laureys Carol Di Perri, Neuroradiology, National Neurological Institute C Mondino, 27100 Pavia, Italy Carol Di Perri, Aurore Thibaut, Lizette Heine, Athena De- mertzi, Steven Laureys, Cyclotron Research Center and Neu- rology Department, Coma Science Group, University of Liège, 4000 Liège, Belgium Andrea Soddu, Brain and Mind Institute, Physics and Astrono- my Department, Western University, London, Ontario, N6A 3K7, Canada Author contributions: Di Perri C designed and wrote the ma- nuscript; Thibaut A, Heine L, Soddu A and Demertzi A were involved in designing and editing the manuscript; Laureys S supervised the manuscript design and writing; all authors were involved in literature search. Supported by The European Commission; the James McDon- nell Foundation; the European Space Agency; Mind Science Foundation; the French Speaking Community Concerted Re- search Action; the Belgian interuniversity attraction pole; the Public Utility Foundation “Université Européenne du Travail”; “Fondazione Europea di Ricerca Biomedica” and the University and University Hospital of Liège Correspondence to: Carol Di Perri, MD, Cyclotron Research Center and Neurology Department, Coma Science Group, Uni- versity of Liège, Allée du 6 août 8, Sart Tilman B30, 4000 Liège, Belgium. caroldiperri@hotmail.com Telephone: +32-43-662316 Fax: +32-43-662946 Received: February 28, 2014 Revised: May 9, 2014 Accepted: June 14, 2014 Published online: August 28, 2014 Abstract Consciousness is a prismatic and ambiguous con- cept that still eludes any universal definition. Severe acquired brain injuries resulting in a disorder of con- sciousness (DOC) provide a model from which insights into consciousness can be drawn. A number of recent studies highlight the difficulty in making a diagnosis in patients with DOC based only on behavioral assess- ments. Here we aim to provide an overview of how neuroimaging techniques can help assess patients with DOC. Such techniques are expected to facilitate a more accurate understanding of brain function in states of unconsciousness and to improve the evaluation of the patient’s cognitive abilities by providing both diagnostic and prognostic indicators. © 2014 Baishideng Publishing Group Inc. All rights reserved. Key words: Disorders of consciousness; Neuroimaging; Magnetic resonance imaging; Transcranial magnetic stimulation/electroencephalography; Minimally con- scious state; Vegetative state/unresponsive wakeful- ness syndrome Core tip: In this review we show the main ways neuro- imaging techniques contribute to both understanding the neural correlates of consciousness and detecting possible consciousness residual in severly traumatic brain injured patients. In particular, we make refer- ence to the latest research in terms of both improving the diagnosis of patients with disorder of conscious- ness, and understanding the brain processes underlin- ing consciousness, such as a broad and more complex than previously thought alteration of brain connectivity architecture. Di Perri C, Thibaut A, Heine L, Soddu A, Demertzi A, Laureys S. Measuring consciousness in coma and related states. World J Radiol 2014; 6(8): 589-597 Available from: URL: http://www. wjgnet.com/1949-8470/full/v6/i8/589.htm DOI: http://dx.doi. org/10.4329/wjr.v6.i8.589 INTRODUCTION Consciousness is a multifaceted and ambiguous concept, which is often the focus of passionate multi-disciplinant debates. Consciousness is thought to represent an emer- gent property of reciprocal connections between special- ized areas of the grey matter within cortical and subcorti- cal networks [1] . To date, there is no universal deinition for consciousness covering all its essential characteristics [2] , making everything particularly tricky and challenging when facing this speciic topic and the related disorders. REVIEW World Journal of Radiology WJR Submit a Manuscript: http://www.wjgnet.com/esps/ Help Desk: http://www.wjgnet.com/esps/helpdesk.aspx DOI: 10.4329/wjr.v6.i8.589 World J Radiol 2014 August 28; 6(8): 589-597 ISSN 1949-8470 (online) © 2014 Baishideng Publishing Group Inc. All rights reserved. 589 August 28, 2014|Volume 6|Issue 8| WJR|www.wjgnet.com