Contributions
Abstract: EP1525
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - MRI and PET
Introduction: MS related cognitive impairment can be measured by neuropsychological testing, but a surrogate marker is lacking. Several biomarker candidates were examined, but neurochemical markers (Sharief and Hentges 1991), structural neuroimaging (Barkhof 1999), PET imaging (Sun et al. 1998) and neurophysiology (Tewarie et al. 2013) only show moderate correlations with neuropsychological measures in group analyses, and do not allow us to reach conclusions at the individual patient level.
Objectives: Our group reported a reduced interhemispheric connectivity for an EEG dataset, indicating a shift from global to local connectivity in cognitively impaired people with MS (PwMS) (Van Schependom et al. 2014). Limitations of this study were the confounding effects of volume conduction, and the low number of electrodes which restricted us to a sensor space analysis. For these reasons we wanted to examine a potential shift from global to local connectivity in fMRI data.
Aims: Our hypothesis was that interhemispheric connectivity would be on average lower in PwMS compared to normal controls, and lower in cognitively impaired in as compared to cognitively preserved PwMS.
Methods: 61 PwMS and 28 Healthy were scanned on a 3T MRI scanner to obtain a 3D T1 weighted image and a 7min rs-functional MRI image. After re-alignment, slice timing correction, co-registration to T1, normalisation to MNI space and global signal regression from non-grey matter , signals were parcellated according to the AAL atlas (Rolls, Joliot, and Tzourio-Mazoyer 2015). Timeseries were extracted for 94 parcels and filtered between 0.009 and 0.08Hz. Pearson correlation coefficients between those timeseries were used as a measure of connectivity.
Results: Interhemispheric connectivity was significantly lower in PwMS compared to matched controls (0.28±0.06 vs 0.31±0.06, p=0.023). Intrahemispheric connectivity did not show a significant difference between groups (p=0.089). Neither measure was significantly different between cognitive preserved and impaired groups.
Conclusions: PwMS show a decreased global organisation on rs fMRI network analysis compared to controls. We were not able to confirm the shift from global to local organisation when comparing cognitively deteriorated patients to cognitively preserved patients. We discuss potential explanations for these findings such as the level of cognitive deterioration in our subjects, dimensionality of the data, and statistical power aspects.
Disclosure: Johan Baijot is funded by an unrestricted grant from Biogen,
Lars Costers is holder of a PhD grant awarded by the Flanders Research Foundation (FWO, www.fwo.be, grant no. 11B7218N).
Jeroen Gielen: nothing to disclose,
Jorne Laton: nothing to disclose,
Melissa Cambron: nothing to disclose,
Johan De Mey: nothing to disclose,
Miguel D'Haeseleer: nothing to disclose,
Marie D'Hooghe has received travel grants, consultancy and speaker fees from Biogen, Teva, Novartis and Genzyme Sanofi.
Anne-Marie Vanbinst: nothing to disclose,
Jeroen Van Schependom is holder of a post- doctoral FWO grant (grant no. 12I1817N).
Guy Nagels holds a research chair by Merck and Novartis.
None of these are likely to be relevant in the context of this manuscript.
Abstract: EP1525
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - MRI and PET
Introduction: MS related cognitive impairment can be measured by neuropsychological testing, but a surrogate marker is lacking. Several biomarker candidates were examined, but neurochemical markers (Sharief and Hentges 1991), structural neuroimaging (Barkhof 1999), PET imaging (Sun et al. 1998) and neurophysiology (Tewarie et al. 2013) only show moderate correlations with neuropsychological measures in group analyses, and do not allow us to reach conclusions at the individual patient level.
Objectives: Our group reported a reduced interhemispheric connectivity for an EEG dataset, indicating a shift from global to local connectivity in cognitively impaired people with MS (PwMS) (Van Schependom et al. 2014). Limitations of this study were the confounding effects of volume conduction, and the low number of electrodes which restricted us to a sensor space analysis. For these reasons we wanted to examine a potential shift from global to local connectivity in fMRI data.
Aims: Our hypothesis was that interhemispheric connectivity would be on average lower in PwMS compared to normal controls, and lower in cognitively impaired in as compared to cognitively preserved PwMS.
Methods: 61 PwMS and 28 Healthy were scanned on a 3T MRI scanner to obtain a 3D T1 weighted image and a 7min rs-functional MRI image. After re-alignment, slice timing correction, co-registration to T1, normalisation to MNI space and global signal regression from non-grey matter , signals were parcellated according to the AAL atlas (Rolls, Joliot, and Tzourio-Mazoyer 2015). Timeseries were extracted for 94 parcels and filtered between 0.009 and 0.08Hz. Pearson correlation coefficients between those timeseries were used as a measure of connectivity.
Results: Interhemispheric connectivity was significantly lower in PwMS compared to matched controls (0.28±0.06 vs 0.31±0.06, p=0.023). Intrahemispheric connectivity did not show a significant difference between groups (p=0.089). Neither measure was significantly different between cognitive preserved and impaired groups.
Conclusions: PwMS show a decreased global organisation on rs fMRI network analysis compared to controls. We were not able to confirm the shift from global to local organisation when comparing cognitively deteriorated patients to cognitively preserved patients. We discuss potential explanations for these findings such as the level of cognitive deterioration in our subjects, dimensionality of the data, and statistical power aspects.
Disclosure: Johan Baijot is funded by an unrestricted grant from Biogen,
Lars Costers is holder of a PhD grant awarded by the Flanders Research Foundation (FWO, www.fwo.be, grant no. 11B7218N).
Jeroen Gielen: nothing to disclose,
Jorne Laton: nothing to disclose,
Melissa Cambron: nothing to disclose,
Johan De Mey: nothing to disclose,
Miguel D'Haeseleer: nothing to disclose,
Marie D'Hooghe has received travel grants, consultancy and speaker fees from Biogen, Teva, Novartis and Genzyme Sanofi.
Anne-Marie Vanbinst: nothing to disclose,
Jeroen Van Schependom is holder of a post- doctoral FWO grant (grant no. 12I1817N).
Guy Nagels holds a research chair by Merck and Novartis.
None of these are likely to be relevant in the context of this manuscript.