1,721,467 research outputs found
MRI measures of neuroprotection and repair in multiple sclerosis
No full textMagnetic resonance imaging (MRI) has had an enormous impact on multiple sclerosis, enabling early diagnosis and providing surrogate markers for monitoring treatment response in clinical trials. Despite these advantages, conventional MRI is limited by lack of pathological specificity and lack of sensitivity to grey matter lesions and to microscopic damage in normal appearing tissue. Quantitative MRI techniques such as measures of parenchymal volume loss, magnetisation transfer imaging, diffusion tensor imaging, and proton magnetic resonance spectroscopy have enhanced our understanding of the nature and mechanism of tissue injury and repair in multiple sclerosis, and provided more specific correlates of neurological deficits and disability accrual. Some of these techniques may be of potential use in clinical trials as surrogate outcome measures for measuring treatment effects on neurodegenerative injury, which is currently difficult to quantify in clinical trials. In this respect, measures of brain volume, T1 hypointensity and magnetisation transfer ratio, and optical coherence tomography appear to be the most promising in the short term. The evidence for a role of neurodegeneration in the pathogenesis of multiple sclerosis, and particularly in the accumulation of irreversible disability, has become increasingly strong over recent years. This has prompted the search for new treatments that can effectively slow down, halt or even reverse such neurodegenerative processes, and in this way restore nervous system function. For this reason, there has been much interest in the development and validation of surrogate markers of neurodegeneration and neuroprotection for use in clinical trials. Advances in magnetic resonance imaging (MRI) technology have allowed the development and implementation of a number of methods that may be promising in this respect. To assess the utility of these methods and to identify needs for further research, sixty experts in neuropathology, clinical measurement, imaging and statistics participated in a meeting held in Amsterdam in 2008 under the aegis of the National Multiple Sclerosis Society. In the proceedings of the meeting, published in 2009 [1], brain volume changes, T1 hypointensity, magnetisation transfer ratio and optical coherence tomography were deemed the most promising measures for screening the neuroprotective capacity of new agents. Other MRI techniques, such as DTI, 1H-MRS and functional MRI, although potentially useful, require more observational data to help determine the optimal trial design. This article will review some of the issues that were discussed at this meeting, and present some of the imaging techniques that were considered to be the most promising. © 2011 Elsevier B.V
MRI in multiple sclerosis: clinical and research update
No full textPurpose of review: Clinical MRI is of paramount importance for multiple sclerosis diagnosis but lacks the specificity to investigate the pathogenic mechanisms underlying disease onset and progression. The application of advanced MR sequences allows the characterization of diverse and complex pathological mechanisms, granting insights into multiple sclerosis natural history and response to treatment.
Recent findings: This review provides an update on the most recent international guidelines for optimal standard imaging of multiple sclerosis and discusses advantages and limitations of advanced imaging approaches for investigating inflammation, demyelination and neurodegeneration. An overview is provided for methods devoted to imaging leptomeningeal enhancement, microglial activation, demyelination, neuronal metabolic damage and neuronal loss.
Summary: The application of magnetic resonance (MR) guidelines to standard-of-care MR protocols, although still limited, would substantially contribute to the optimization of multiple sclerosis management. From an academic perspective, different mechanism-specific imaging techniques are available and offer a powerful tool to elucidate multiple sclerosis pathogenesis, monitor disease progression and guide therapeutic choices
Imaging multiple sclerosis and other neurodegenerative diseases
No full textAlthough the prevalence of neurodegenerative diseases is increasing as a consequence of the growing aging population, the exact pathophysiological mechanisms leading to these diseases remains obscure. Multiple sclerosis (MS), an autoimmune disease of the central nervous system and the most frequent cause of disability among young people after traumatic brain injury, is characterized by inflammatory/demyelinating and neurodegenerative processes that occurr earlier in life. The ability to make an early diagnosis of MS with the support of conventional MRI techniques, provides the opportunity to study neurodegeneration and the underlying pathophysiological processes in earlier stages than in classical neurodegenerative diseases. This review summarizes mechanisms of neurodegeneration common to MS and to Alzheimer disease, Parkinson disease and amiotrophic lateral sclerosis, and provides a brief overview of the neuroimaging studies employing MRI and PET techniques to investigate and monitor neurodegeneration in both MS and classical neurodegenerative diseases
Quantitative MRI: Hidden age-related changes in brain tissue
No full textThe advent of MRI has made a remarkable progress in the understanding of age-related brain changes providing a noninvasive tool to study in vivo the normally aging individuals at multiple time points. However, conventional MRI techniques are unable to detect and quantify age-related microstractural changes that have been documented at the post-mortem examination of brain tissues. More sophisticated, quantitative MR techniques such as magnetization transfer imaging, diffusion tensor imaging, and proton MR spectroscopy have been shown to be sensitive to microsrructural and metabolic changes that occur in gray and white matter over the course of life span. This review highlights some of these innovative, quantitative MR techniques that are particularly relevant for the study of occult age-related brain tissue changes. Characterization of the in vivo patterns of molecular and cellular changes that occur in the normal aging brain is of crucial importance to understand the pathophysiology of normal cognitive decline and to interpret observed changes in neurodegenerative diseases. Copyright © 2005 by Lippincott Williams & Wilkins
Diffusion imaging in multiple sclerosis: Research and clinical implications
No full textMultiple sclerosis (MS) is an inflammatory-demyelinating and neurodegenerative disease of the central nervous system (CNS) and the most frequent cause of non-traumatic disability in young and middle-age adults. Although conventional MRI (including T2-weighted, pre- and post-contrast T1-weighted scans) has had a huge impact on MS by enabling an earlier diagnosis, and by providing surrogate markers for monitoring treatment response, it is limited by the low pathological specificity and the low sensitivity to diffuse damage in normal-appearing white matter and gray matter. Diffusion weighted MRI is a quantitative technique able to overcome these limitations by providing markers more specific to the underlying pathologic substrates and more sensitive to the full extent of 'occult' brain tissue damage. This review describes diffusion studies in MS, discusses their pathophysiological implications and emphasizes their clinical relevance. © 2010 John Wiley & Sons, Ltd
Therapeutic strategies in multiple sclerosis: A focus on neuroprotection and repair and relevance to schizophrenia
No full textMultiple sclerosis is the leading nontraumatic cause of neurologic disability in young adults. The need to prevent neurodegeneration and promote repair in multiple sclerosis (MS) has gained increasing interest in the last decade leading to the search and development of pharmacological agents and non-pharmacologic strategies able to target not only the inflammatory but also the neurodegenerative component of the disease. This paper will provide an overview of the therapeutics currently employed in MS, with a focus on their potential neuroprotective effects and on the MRI methods employed to detect and monitor in-vivo neuroprotection and repair and the relevance of this information to schizophrenia investigation and treatment. (C) 2014 Elsevier B.V. All rights reserved
Functional neuroradiology of traumatic brain injury
No full textTraumatic brain injury (TBI) is one of the most important causes of morbidity and mortality in the modern world. Each year in USA alone, more than two million people sustain a head trauma, and 10% of these injuries are fatal [1]. In addition, 10% of survivors experience neurological deficits of varying degrees [2], and it is estimated that as many as 5.3 million people are living in USA with disability related to TBI, approximately 2% of the population [3]. The leading cause of TBI is injury related to falls, followed by motor-vehicle or traffic collisions, and external cause of being “struck by or against” [1]. The classification of the clinical severity of TBI is based on the Glasgow Coma Scale (GCS) [4]. The GCS is a neurological scale that allows the recording of the level of consciousness through the assessment of eye, motor, and verbal responses. The severity distribution is approximately 80% mild (GCS score of 13-15), 10% moderate (GCS score of 12-9), and 10% severe (GCS scores of 8 or less)
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