753 research outputs found
The role of thalamic damage in mild traumatic brain injury
No full textThere is growing alarm in the United States about an epidemiologically large occurrence of mild traumatic brain injury with serious long lasting consequences. Although conventional imaging has been unable to identify damage capable of explaining its organic origin or discerning patients at risk of developing long-term or permanently disabling neurological impairment, most disease models assume that diffuse axonal injury in white matter must be present but is difficult to resolve. The few histopathological investigations conducted, however, show only limited evidence of such damage, which cannot account for the stereotypical globalized nature of symptoms generally reported in patients. This review examines recent proposals that in addition to white matter, the thalamus may be another important further site of injury. Although its possible role still remains largely under-investigated, evidence from experimental human and animal models, as well as simulational and analytical representations of mild head injury and other related conditions, suggest that this strategically vital region of the brain, which has reciprocal projections to the entire cerebral cortex, could feasibly play an important role in understanding pathology and predicting outcome
Predicting short-term conversion from CIS to MS: Relevance of lesion distribution
No full textClinically isolated syndrome (CIS) describes a first symptomatic neurologic episode that is consistent with multiple sclerosis (MS), lasts at least 24 hours, occurs in the absence of fever or infection, and presents without encephalopathy.(1) Its cause is inflammation or demyelination in one (i.e., monofocal episode) or multiple areas (i.e., multifocal episode) of the CNS. Symptoms are those commonly found in MS and include, for example, optic neuritis, sensory or motor signs, partial myelitis, and bladder or bowel dysfunction.(1)
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
Overview of diffusion-weighted magnetic resonance studies in multiple sclerosis
No full textDiffusion-weighted magnetic resonance imaging (DW-MRI) provides a unique form of MR contrast that enables the diffusional motion of water molecules to be quantitatively measured. As a consequence, DW-MRI provides information about the size, shape, integrity, and orientation of brain structures. Pathological processes able to alter tissue integrity by removing or modifying some of the structural barriers that normally restrict water molecular motion in biological tissues cause changes in water diffusion characteristics, which can be measured in-vivo using DW-MRI. Although DW-MRI has been shown to be of great clinical utility in the assessment of patients with cerebral ischemia, it is also increasingly being used to quantify in-vivo the extent and severity of multiple sclerosis (MS) pathology. The pathological elements of MS have the potential to alter the permeability or geometry of structural barriers to water molecular motion in the brain, optic nerve and spinal cord. The present review outlines the major contributions given by DW-MRI for the quantification of MS-related damage and for the understanding of MS pathophysiology
<i>B</i> <sub>0</sub> inhomogeneity-insensitive triple-quantum-filtered sodium imaging using a 12-step phase-cycling scheme
No full textTriple-quantum-filtered (TQF) sodium MRI can be used to separate sodium NMR signals from different physiological compartments. Although three-pulse triple-quantum filtering has been demonstrated to be better suited for in vivo imaging, the absence of the refocusing pulse in the filter increases its sensitivity to magnetic field inhomogeneities. Therefore, several TQF cycles have been developed previously to correct image distortions caused by B(0) inhomogeneities. In this paper, we present a new 12-step phase-cycling TQF scheme based on three radiofrequency pulses which allows the compensation of B(0) variations both with and without ancillary B(0) map information. The method offers 40% higher signal-to-noise-ratio efficiency compared with the previously developed B(0)-correcting phase-cycling schemes
Microvessel density estimation in the human brain by means of dynamic contrast-enhanced echo-planar imaging
No full textScan-rescan variation of measures derived from brain magnetization transfer ratio histograms obtained in healthy volunteers by use of a semi-interleaved magnetization transfer sequence
No full textA novel semiinterleaved gradient-echo (GE) sequence for quantitative measurement of magnetization transfer ratio (MTR) is described. With this sequence, several lines of k-space are collected for the non-MT image then several lines are collected for the MT image, thus building up the entire k-space in distinct acquisition blocks, with a good trade-off between motion-induced misregistration and degree of MT effect. The scan-rescan coefficients of variation for several MTR histogram-derived measures from 10 healthy volunteers scanned serially with this semiinterleaved sequence proved to be lower than those achieved using a conventional GE sequence. This sequence may be useful in a clinical environment to measure MTR changes over time more reliably than when acquiring the non-MT and MT images sequentially, which inevitably are affected by patient motion
Neuroimaging of Multiple Sclerosis, Acute Disseminated Encephalomyelitis, and Other Demyelinating Diseases
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