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  • 1
    ISSN: 1432-1459
    Keywords: Acute myelopathy ; Magnetic resonance imaging ; Evoked potentials ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Brain and spinal cord magnetic resonance imaging (MRI), multimodal evoked potentials (EPs) and cerebrospinal fluid (CSF) analysis were performed in 27 patients with acute myelopathy of unknown aetiology (AMUA), to detect the diagnostic and prognostic values of paraclinical tests at presentation. Spinal cord MRI was abnormal in 56% and brain MRI in 33% of the patients. Visual EPs were abnormal in 7%, median somatosensory EPs in 17%, tibial somatosensory EPs in 56% and motor EPs in 35% of the cases examined. Brain-stem acoustic EPs were normal in all the patients. CSF oligoclonal bands (OBs) were detected in 30% of cases. The patients were divided into subgroups according to the short-term clinical outcome (complete, partial or absent recovery). There were no significant differences among the three groups as regards MRI findings. Patients with complete recovery showed a significantly lower frequency of tibial somatosensory EP and motor EP abnormalities. According to the paraclinical findings at onset and on the basis of a long-term clinical follow-up (mean duration 24 months), 6 patients were diagnosed as having clinically definite multiple sclerosis, while 21 did not develop further neurological disturbances. Only the presence of CSF OBs was significantly more frequent in patients with definite multiple sclerosis. Our study indicates that EPs exploring spinal cord function are more powerful than spinal MRI for predicting the short-term outcome of AMUA, while the combined use of brain MRI and CSF OBs has the highest negative predictive value for the subsequent development of clinically definite multiple sclerosis.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Conventional spin-echo ; Fast ; fluid-attenuated inversion recovery ; Post-contrast T1-weighted scans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In this longitudinal study, the sensitivities of three magnetic resonance imaging techniques for detecting the appearance of new lesions in multiple sclerosis (MS) were evaluated and compared. Dual-echo conventional spin-echo (CSE), fast fluid-attenuated inversion recovery (fast-FLAIR) and post-contrast T1-weighted scans were obtained on four occasions, each separated by 28 days, from 18 patients with relapsing-remitting MS using a 1.5-T machine. New lesions seen using each sequence during the follow-up were counted by agreement by four observers in two stages (stage 1: random review of complete sets of scans from each technique; stage 2: side-by-side review with a ‘retrospective’ count of new lesions). At stage 1, 1.44 new lesions per patient per month were detected on CSE scans, 1.88 on fast-FLAIR (31% more than CSE) and 2.07 on post-contrast T1-weighted scans (44% more than CSE) (P = 0.03). Differences were, however, reduced after stage 2: fast-FLAIR detected 29% and post-contrast T1-weighted scans detected 31% more new lesions than CSE (P = 0.08). The combination of fast-FLAIR and post-contrast scans detected 144 new lesions, whilst the usual combination of CSE and post-contrast scans detected 133 new lesions. This study indicates that enhanced MRI remains the most sensitive method for detecting ‘active’ lesions in MS and that fast-FLAIR may be used when monitoring short-term disease activity in MS, either natural or modified by treatment.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Fatigue ; Magnetic resonance ; imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fatigue is a frequent and often severe symptom in multiple sclerosis. Pathogenic mechanisms proposed for fatigue include the release of proinflammatory cytokines, which is thought to have an important effect on changes in the blood-brain barrier (BBB). To investigate whether fatigue is related to BBB disruption we studied 11 relapsing-remitting MS patients participating in a multicenter longitudinal study comparing the sensitivity of monthly enhanced magnetic resonance imaging (MRI) after standard-dose and triple-dose injection of gadolinium-diethylene triaminopentoacetic acid (Gd-DTPA). Serial Gd-enhanced MRI studies were performed in two separate sessions every 4 weeks for 3 months. An expanded version of the Fatigue Severity Scale, including 29 items, was administered 24 h before each MRI examination. No relationship was found between the number and volume of Gd-enhancing lesions and fatigue scores at any monthly examination over the study period. Furthermore changes in MRI activity were not significantly related to changes in fatigue scores. These results were obtained on triple-dose delayed scanning, which is more sensitive than standard-dose scanning in detecting areas of BBB disruption. Our preliminary results thus do not support the hypothesis of a relationship between BBB alterations and fatigue severity in multiple sclerosis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Gadolinium-DTPA ; Triple dose ; Blood-brain barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study assessed whether dysfunction of the blood-brain barrier is an obligatory early event in lesion formation in multiple sclerosis. Dual-echo and T1-weighted magnetic resonance imaging after the injection of a triple dose (0.3 mmol/kg) of gadolinium-DTPA were obtained from ten patients with relapsing-remitting multiple sclerosis every week for 2 months. Sixty-four newly active lesions were detected by the two techniques. All the 44 new lesions seen on dual-echo scans enhanced during the early phases of their formation: 33 at their first appearance, 10 1 week before their appearance on the dual-echo scans, and one the week thereafter. When the every fourth (monthly) scan was analyzed, a total of 55 newly active lesions were detected (i.e., 14% active lesions would have been missed compared to the number found on weekly scanning). Thirty-one of them were detected by both dual-echo and triple-dose scans, 15 only by enhanced scans, and nine only by dual-echo scans. This study confirms that with highly sensitive magnetic resonance imaging techniques dysfunction of the blood-brain barrier is an obligatory early event in new lesion formation in relapsing-remitting multiple sclerosis.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Italian journal of neurological sciences 20 (1999), S. S227 
    ISSN: 1126-5442
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Italian journal of neurological sciences 20 (1999), S. S232 
    ISSN: 1126-5442
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetization transfer imaging (MTI) is a magnetic resonance imaging (MRI) technique that is now used in multiple sclerosis (MS) studies, and is thought to have a higher pathological specificity than conventional T2-weighted imaging. This review outlines the major contributions given by MTI for the understanding of MS evolution. MTI studies of individual MS lesions confirm the pathological heterogeneity of T2-weighted MRI abnormalities and the potential role of unenhanced T1-weighted hypointensities as specific markers of localized severe white matter disruption. Correlative cross-sectional and longitudinal studies using MIT and gadolinium (Gd)-enhanced MRI reveal that MTI findings may vary in lesions with different patterns of enhancement, and that MTI abnormalities are closely related to the onset and recovery of blood-brain barrier disruption in new MS plaques. MTI lesion load (LL) is highly correlated with T2-weighted MRI lesion load, but it has a limited reliability as a measure of MS lesion burden. On the other hand, measures obtained from MT scans using whole-brain histogram analysis are highly correlated with the extent of MS abnormalities on conventional MRI scans, and predict patients' clinical disability well, since they are sensitive to both macro- and microscopic MS lesion burden in the whole brain and in specific regions. These data suggest that (a) MTI is sensitive to different stages of lesion pathology and pathological evolution in MS patients; and (b) MT histogram analysis can provide a more global assessment of MS lesion burden, since it encompasses both macro- and microscopic MS pathology.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Italian journal of neurological sciences 20 (1999), S. S246 
    ISSN: 1126-5442
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Diffusion-weighted imaging (DWI) provides a unique form of magnetic resonance (MR) contrast that enables the diffusional motion of water molecules to be quantitatively measured. As a consequence, DWI provides information about the orientation, size and geometry of brain structures. Cellular structures in the central nervous system restrict water molecular motion, and the apparent diffusion coefficient (ADC) is reduced compared to diffusion in bulk water. Pathological processes that modify tissue integrity, thus removing some of the “restricting” barriers, can result in increased ADC. Preliminary studies in multiple sclerosis (MS) using DWI showed that the ADC is higher in macroscopic lesions than in the normal appearing white matter (NAWM). The ADC is also dependent on the direction in which diffusion is measured, thus making comparison of ADC values meaningless without taking into account the measurement direction. One measurement of diffusion that is independent of the orientation of structures is provided by measuring the ADC in three orthogonal directions, and then averaging the results to form the mean diffusivity, ${\overline D}$ . We obtained DW scans from 35 patients with relapsing-remitting MS and 24 healthy volunteers. ${\overline D}$ was measured inside T2-visible lesions and regions located in different areas of the NAWM. ${\overline D}$ histograms from a large portion of the brain were created. MS lesions had a significantly higher ${\overline D}$ than NAWM. T1-hypointense lesions had the highest diffusion values, consistent with more severe tissue disruption. ${\overline D}$ was higher in the NAWM from patients than in the white matter from healthy controls. We also found significant differences between ${\overline D}$ histogram-derived measures from patients and controls, confirming the presence of diffuse damage in the brain of patients with MS.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Magnetisation tranfer imaging ; Spinal cord ; Measurement ; reproducibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract New magnetic resonance (MR) measures considered to be putative markers of demyelination and axonal loss were found to be more closely related to clinical disability than T2-weighted MR imaging (MRI) findings in patients with multiple sclerosis (MS). In this study, we evaluated the reproducibility of such measurements in order to assess their reliability for longitudinal studies in MS. The intra-observer coefficients of variation for repeated measurements did not significantly differ among the MR techniques studied [2.6% for T2-weighted MRI, 4.38% for unenhanced T1-weighted MRI, 3.65% for magnetisation transfer imaging (MTI) and 2.28% for spinal cord cross-sectional area at C5]. Our findings suggest that non-conventional MR techniques may be reliable outcome measures for clinical trials in MS.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Brain magnetic resonance imaging ; Repositioning ; Clinical trials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to assess the variability of lesion load measurements for repeated brain magnetic resonance imaging (MRI) scans judged to have either poor or good repositioning quality on the basis of subjective criteria used for clinical trials in multiple sclerosis (MS). Scan-rescan variability was also compared with the intra-observer variability assessed from three repeated volume measurements of the same scan. Nine patients with MS were studied; each of them underwent the scan-rescan procedure on the same day. Five scans were considered to have poor and four scans to have good repositioning. Between these two groups there were no differences in either the mean lesion loads or the measurement variance. For the whole group of patients, the intra-observer variability of repeated measurements gave a significantly lower coefficient of variation (COV=4.9%) than the variability owing to repositioning (COV=8.9%, P〈0.01, F test). Our results confirm that the effect of repositioning on brain MRI lesion load assessment is stronger than that owing to the intra-observer variability for repeated measurements and indicate that the simple visual judgment about the scan repositioning quality seems unable to predict the scan-rescan reproducibility.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Disease activity ; Fast spin echo ; Fast fluid-attenuated inversion ; recovery ; Reproducibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Previous studies have addressed the question of the precision in assessing multiple sclerosis (MS) activity by counting enhancing lesions on gadolinium enhanced brain magnetic resonance imaging (MRI). However, counting the active lesions on serial unenhanced MRI obtained by various pulse sequences has not been yet considered. We compared the interobserver levels of agreement in reporting active MS lesions on serial enhanced and unenhanced MRI to assess whether the use of various unenhanced techniques may change the degree of interobserver measurement reproducibility. Dual-echo conventional spin echo (CSE), dual-echo fast spin echo (FSE), fast fluid-attenuated inversion recovery (FLAIR) and Gd-enhanced T1-weighted brain MRI were obtained from five MS patients at baseline and monthly for 2 months. Six experienced observers independently identified and counted active MS lesions on the two follow-up MRI scans. Active lesions were considered to be all the enhancing lesions and any new or enlarging lesion on enhanced and unenhanced scans. Interobserver levels of agreement were calculated by weighted κ values. Very good agreement was reached only for counting total and new Gd-enhancing lesions. Good agreement was achieved for counting new lesions on the three unenhanced techniques, whereas the agreement for counting enlarging lesions was poor with all the MRI techniques. The level of agreement was significantly heterogeneous for various MRI techniques but not for various lesion sites. These results confirm that counting enhancing lesions is the most reliable method for assessing MS activity, but the use of any of the available unenhanced MRI techniques did not result in different levels of interobserver agreement when reporting new and enlarging MS lesions on serial scans.
    Type of Medium: Electronic Resource
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