Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Strategies for optimizing MRI techniques aimed at monitoring disease activity in multiple sclerosis treatment trials (1997)
    Springer
    Journal of neurology 244 (1997), S. 76-84 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Trial design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Serial magnetic resonance imaging (MRI) detects substantial subclinical disease activity in multiple sclerosis (MS) and is presently included in most treatment trials as an objective outcome measure. Our current knowledge of the role of MRI in MS treatment trials is derived from very limited patient studies, and the aim of this paper is to identify strategies to optimize the use of MRI in monitoring disease activity in treatment trials. The number of active lesions revealed by MRI can be used as the primary outcome measure in exploratory treatment trials. With monthly scanning, the majority of active lesions will be seen by virtue of a limited number of new areas of gadolinium enhancement. The contrast between enhancing lesions and background could be increased by: (1) using higher doses of gadolinium, (2) suppressing the background signal with magnetization transfer, (3) delayed scanning, or (4) a combination of these. Following a systematic comparison of those approaches, the effect on the sensitivity in detecting active lesions should be analysed with reference to the power of treatment trials. We present preliminary results showing marked agreement between observers in reporting enhancing lesions; however, with new acquisition strategies, the observer variation should be re-established in a multicentre fashion. In definitive trials, the increase in total lesion load serves as a secondary outcome measure. Since the majority of lesions making up the total lesion load are inactive during the study, spatial resolution should be maximized in order to preclude any artificial changes in lesion load to be superimposed (noise) upon the relatively small actual change (information). Reduction in measurement error can be attempted by improved acquisition techniques with increased lesion to background contrast. More importantly, improvement in quantitation techniques is warranted. With a 6% coefficient of variation in measuring a baseline lesion load, we calculate the standard error of the mean yearly increase in T2 lesion load (typically 10% in untreated patients) in a treatment arm of 124 patients to be 7.5%. A comparison of several quantitation techniques should be performed in a multicentre longitudinal fashion in order to include variation caused by both scanner and segmentation technique, in addition to biological activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050053
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Functional correlates of callosal atrophy in relapsing-remitting multiple sclerosis patients. A preliminary MRI study (1998)
    Springer
    Journal of neurology 245 (1998), S. 153-158 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Periventricular lesions ; Callosal ; atrophy ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In multiple sclerosis (MS), periventricular lesions produce atrophy of the corpus callosum (CC), as evidenced by magnetic resonance imaging (MRI). We investigated whether CC atrophy in relapsing-remitting MS patients is related to functional deficits. We compared 14 mildly disabled (mean Expanded Disability Status Scale score 2.7) relapsing-remitting MS patients with 14 age- und sex-matched controls. CC size was determined using sagittal T1-weighted MRI. The function of the CC was studied using a neuropsychological battery and neurophysiological evaluation based on visual stimulation using a divided visual field paradigm. The total area of the CC in patients (mean 5.3cm2) was significantly (P=0.002) smaller than in controls (mean 6.6cm2). Patients showed left ear extinction using the dichotic listening test and impaired name learning, which was correlated with atrophy of the splenium. There were no differences in interhemispheric transfer time between patients and controls. Marked atrophy of the CC can be encountered in relapsing-remitting MS patients. The associated cerebral disconnection correlated with atrophy of expected regions of the CC, thus supporting topographical organization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050196
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Multiple sclerosis: interobserver agreement in reporting active lesions on serial brain MRI using conventional spin echo, fast spin echo, fast fluid-attenuated inversion recovery and post-contrast T1-weighted images (1999)
    Springer
    Journal of neurology 246 (1999), S. 920-925 
    Details
    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
    URL: http://dx.doi.org/10.1007/s004150050483
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The use of magnetic resonance imaging in multiple sclerosis treatment trials: power calculations for annual lesion load measurement (2000)
    Springer
    Journal of neurology 247 (2000), S. 34-40 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Treatment trial ; Power calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Phase III definitive treatment trials of new multiple sclerosis (MS) therapies now routinely incorporate an annual magnetic resonance imaging protocol, with change in T2-weighted brain lesion load providing an important outcome measure. To date the accepted strategy has been to perform a core imaging protocol on all patients in such studies. The aim of this study was to provide power calculations based on this MRI endpoint. Serial MRI data from 128 patients with either relapsing remitting (RR) or secondary progressive (SP) MS were used to calculate sample size requirements using a repeated measures analysis of variance design. We provide sample size calculations based on various follow-up intervals and effect sizes. Sample sizes for the SPMS cohort were substantially larger than for the RRMS group, reflecting the greater variance in lesion load changes between patients in the SPMS group. With a follow-up of 3 years, we estimate that only 12 and 33 patients per arm are needed to show stabilisation of MRI lesion load in the RRMS and SPMS groups, respectively. Our results suggest that ongoing phase III treatment trials are more than adequately powered to detect even subtle treatment effects, and indicate that incorporating measurements from longer follow-up durations increases power substantially. We conclude that an annual imaging protocol provides a robust and powerful tool for assessing effects on the radiological appearance of the disease process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050007
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Interobserver agreement for diagnostic MRI criteria in suspected multiple sclerosis (1999)
    Springer
    Neuroradiology 41 (1999), S. 347-350 
    Details
    ISSN: 1432-1920
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Interobserver variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI is the paraclinical test most widely used to support the diagnosis of multiple sclerosis (MS). We evaluated interobserver agreement in applying diagnostic criteria to MRI obtained at first presentation. Five experienced observers scored 25 sets of images consisting of unenhanced T2- and gadolinium-enhanced T1-weighted images (approximately half the sets were normal). We scored frontal, parietal, temporal, occipital, infratentorial and basal ganglia lesions and the total number of lesions on T2-weighted images; periventricular, callosal, juxtacortical and ovoid lesions and those 〉 5 mm in maximum diameter; contrast-enhancing and hypointense lesions. Based on a combination of imaging findings patients were classified as compatible or not compatible with MS according to composite criteria. Observer concordance was characterised by weighted kappa values (ϰ) and mean average difference to the median (MADM) scores. Using the raw scores, there was poor agreement for the total number of lesions on T2-weighted images, and for occipital, oval, juxtacortical and hypointense lesions. Moderate agreement was found for frontal, callosal, basal ganglia and large lesions on T2 weighting. Good agreement was attained for parietal, temporal, infratentorial and periventricular lesions. After dichotomisation according to accepted cut-off values, most criteria performed better, especially the number of lesions on T2-weighted images (P 〈 0.05). Good agreement was found for the criteria of Paty and Fazekas and moderate agreement for those of Barkhof. While experienced observers may not agree on the total number of lesions, they show quite good agreement for commonly used cut-off points and elements in the composite criteria. This validates the use of MRI in the diagnosis of MS, and the use of dichotomised and composite criteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050762
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Visual analysis of serial T2-weighted MRI in multiple sclerosis: intra- and interobserver reproducibility (1999)
    Springer
    Neuroradiology 41 (1999), S. 882-888 
    Details
    ISSN: 1432-1920
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated the effect of consensus formation and training on the agreement between observers in scoring the number of new and enlarging multiple sclerosis (MS) lesions on serial T2-weighted MRI studies. The baseline and month 9 MRI studies of 16 patients with a range of MRI activity were used (dual-echo conventional spin-echo sequence, TR 2000, TE 34 and 90 ms, 5 mm contiguous slices, in-plane resolution 1 mm). First, the serial studies were visually analysed for the presence of new and enlarging lesions, on two occasions, by five experienced observers, without adopting any consensus strategy and in isolation. Next, the observers met to identify the common sources of inconsistencies in reporting between observers and formulate consensus rules. Finally, a further independent reading session was performed on the same MRI dataset, this time applying the consensus rules. Agreement between observers was assessed using kappa scores. Without the consensus rules, interobserver kappa scores for the first and second reading sessions for new lesions were only 0.51 and 0.39 respectively; agreement for enlarging lesions was even worse. The mean intraobserver kappa score for new lesions was higher at 0.72, reflecting the fact that the observers were consistently applying their individual assessment strategies. Application of the consensus rules did not lead to a significant improvement in inter observer kappas; the kappa scores adopting the guidelines were 0.46 and 0.21 for new and enlarging lesions respectively. Consensus guidelines thus did not improve the reproducibility of visual analysis of serial T2-weighted MRI, and the level of agreement between observers remained only moderate. Suboptimal repositioning is likely to be a major source of residual variability and this suggests a future role for image registration strategies; until then, a single observer, or pair of observers working in consensus, should be used in MS studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050860
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...