Multiple sclerosis : clinical and laboratory research
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The 9-item, Fatigue Severity Scale (FSS-9) has been widely used as an outcome measure in multiple sclerosis (MS). Modern psychometric theory, in the form of the Rasch measurement model, has set new quality standards for outcome measures by appraising a broad range of measurement properties in addition to the reliability and validity emphasized by classical test theory. ⋯ Summating the nine items of the FSS-9 is invalid. Five items (FSS-5), which seem to be measuring the social impact of fatigue, provide a strictly unidimensional Rasch scale. Studies using the FSS-9 may need to be re-evaluated using the FSS-5, preferably using the Rasch transformed scores.
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Quantitative magnetization transfer magnetic resonance imaging (qMT-MRI) can be used to improve detection of white matter tissue damage in multiple sclerosis (MS) and animal models thereof. To study the correlation between MT parameters and tissue damage, the magnetization transfer ratio (MTR), the parameter f* (closely related to the bound proton fraction) and the bound proton transverse relaxation time T(2B) of lesions in a model of focal experimental autoimmune encephalomyelitis (EAE) were measured on a 7T animal scanner and data were compared with histological markers indicative for demyelination, axonal density, and tissue damage. A clear spatial correspondence was observed between reduced values of MTR and demyelination in this animal model. ⋯ No changes in T(2B) were observed for the lesions. We conclude that MTR and qMT mapping are efficient and reliable readouts for studying demyelination in animal models of MS, and that the analysis of regional f* might be even superior to the analysis of MTR values. Therefore, quantitative mapping of f* from human brains might also improve the detection of white matter damage in MS.