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Jean Pelletier - One of the best experts on this subject based on the ideXlab platform.
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magnetic resonance study of the influence of tissue damage and cortical reorganization on pasat performance at the Earliest Stage of multiple sclerosis
Human Brain Mapping, 2005Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the Earliest Stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the Earliest Stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT.
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modulation of effective connectivity inside the working memory network in patients at the Earliest Stage of multiple sclerosis
NeuroImage, 2005Co-Authors: M Au V Duong, Bertrand Audoin, Danielle Ibarrola, S Confortgouny, Irina Malikova, Jean Pelletier, Kader Boulanouar, S Treseras, P Celsis, P J CozzoneAbstract:fMRI and structural equation modeling (SEM) were used to study effective connectivity inside the working memory network in patients at the Earliest Stage of multiple sclerosis (MS), while performing paced auditory serial addition test (PASAT), a sensitive task to reveal subtle cognitive impairments related to working memory and information speed processing. The path model used for SEM included bilateral connections between left and right BA 46, left and right BA 40, left and right anterior cingulate cortex (ACC), left BA 44 and left BA 40, right BA 44 and right BA 40, and unidirectional ipsilateral connections from BA 46 to BA 44, from ACC to BA 46, and from ACC to BA 44. Experimental data from the two groups fit accurately the working memory model, in patients [χ(20)2 = 13, P = 0.877] as well as in controls [χ(20)2 = 13.54, P = 0.853]. The omnibus test indicated a significant difference of model fits in patients and in controls [χ(40)2 = 160.07, P < 0.0001]. Connectivity strengths from right BA 46 to left BA 46, from left ACC to left BA 46 were lower in patients than in controls, and higher from right ACC to right BA 46, from left to right and from right to left ACC (stacked model). Effective connectivity inside the working memory network appears altered in patients at the Earliest Stage of MS. Modulation of effective connectivity is present in patients inside the executive subsystems of working memory, and could be related to adaptive cognitive control processes that may limit the clinical manifestation of MS.
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local tissue damage assessed with statistical mapping analysis of brain magnetization transfer ratio relationship with functional status of patients in the Earliest Stage of multiple sclerosis
American Journal of Neuroradiology, 2005Co-Authors: Jeanphilippe Ranjeva, Bertrand Audoin, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, D Ibarrola, Jean PelletierAbstract:BACKGROUND AND PURPOSE: In the early Stage of Multiple Sclerosis (MS), conventional MR imaging parameters such as T2 lesion load fail to explain the clinical status of patients. In the present work, we aimed to determine the ability of magnification transfer imaging to better reflect the relationship between local tissue damage and functional status of MS patients. METHODS: We performed a comparative statistical mapping analysis on brain tissue magnetization transfer ratio (MTR) data measured in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) and 18 matched control subjects. RESULTS: In the patients with CISSMS, a pattern of significant low MTR values was observed in the white matter, corpus callosum, bilateral occipitofrontal fascicles, right fornix, right parietal white matter, external capsule, right superior longitudinal fasciculus (SLF), right inferior longitudinal fasciculus, optica radiata, parietal white matter, right cingulum, gray matter, bilateral thalamus, bilateral caudate, right insula, and left Brodmann area (BA) 8. No correlation was found between local MTR decrease and Expanded Disability Status Scale score. Significant correlations between MTR and MS Functional Composite scores (Spearman rank test, P <.05) were observed in the left BA40, right SLF, right frontal white matter, splenium, and anterior corpus callosum. Local MTR values correlated with Paced Auditory Serial Addition Test scores in the left BA40, right BA4, right SLF, and splenium. CONCLUSION: Statistical mapping analysis of brain MTR data provides valuable information on the relationship between the location of brain tissue damage and its functional impact in patients with MS, even in the Earliest Stage of the disease.
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Magnetic resonance study of the influence of tissue damage and cortical reorganization on PASAT performance at the Earliest Stage of multiple sclerosis.
Human Brain Mapping, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, Irina Malikova, My Van Au Duong, Elisabeth Soulier, P Viout, Sylviane Confort-gouny, André Ali-chérif, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the Earliest Stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the Earliest Stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT. Hum. Brain Mapping 24:216–228, 2005. © 2004 Wiley-Liss, Inc.
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voxel based analysis of mtr images a method to locate gray matter abnormalities in patients at the Earliest Stage of multiple sclerosis
Journal of Magnetic Resonance Imaging, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, Jean PelletierAbstract:Purpose To determine whether voxel-based analysis of magnetization transfer ratio (MTR) maps can provide evidence of a coherent pattern of gray matter (GM) macroscopic and microscopic tissue damage in patients at the Earliest Stage of multiple sclerosis (MS). Materials and Methods We acquired GM MTR maps in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS), and 18 sex- and age-matched healthy controls. We evaluated the clinical status of the patients using the MS functional composite score and the expanded disability status scale. A two-sample t-test (P < 0.0001, k = 20, uncorrected for height threshold) was used to compare GM MTR maps from patients and controls on a voxel-by-voxel basis. We then extracted data from regions with t-values above the statistical threshold to verify the significance of differences using a nonparametric Mann-Whitney U-test. Results A between-groups comparison of GM maps revealed large abnormalities in the basal ganglia, including the bilateral thalamus, bilateral lenticular nucleus, bilateral head of caudate, and protuberance, and smaller abnormalities in the right insula, right BA 4, and left BA 40. The MTR measured in the left caudate and right insula was inversely correlated with duration following the first clinical event. Conclusion These results suggest that although MS is a multifocal demyelinating disease that affects white matter (WM), a pattern of tissue damage is present inside the GM involving predominantly basal ganglia at the Earliest Stage of the disease. J. Magn. Reson. Imaging 2004;20:765–771. © 2004 Wiley-Liss, Inc.
Sten Eirik W Jacobsen - One of the best experts on this subject based on the ideXlab platform.
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expression and role of flt3 in regulation of the Earliest Stage of normal granulocyte monocyte progenitor development
Blood, 2010Co-Authors: Charlotta Boiers, Natalija Buzavidas, Christina T Jensen, Cornelis J H Pronk, Shabnam Kharazi, Lilian Wittmann, Ewa Sitnicka, Anne Hultquist, Sten Eirik W JacobsenAbstract:Mice deficient in FLT3 signalling have reductions in early multipotent and lymphoid progenitors, whereas no evident myeloid phenotype has been reported. However, activating mutations of Flt3 are among the most common genetic events in acute myeloid leukemia and mice harbouring internal tandem duplications within Flt3 (Flt3-ITD) develop myeloproliferative disease, with characteristic expansion of granulocyte-monocyte (GM) progenitors, possibly compatible with FLT3-ITD promoting a myeloid fate of multipotent progenitors. Alternatively, FLT3 might be expressed at the Earliest Stages of GM development. Herein, we investigated the expression, function and role of FLT3 in recently identified early GM progenitors. Flt3-cre fate mapping established that most progenitors and mature progeny of the GM lineage are derived from Flt3 expressing progenitors. A higher expression of FLT3 was found in preGMP compared to GMP, and preGMPs were more responsive to stimulation with FLT3 ligand (FL). Whereas preGMPs and GMPs were reduced in Fl(-/-) mice, megakaryocyte-erythroid progenitors were unaffected and lacked FLT3 expression. Notably, mice deficient in both Thrombopoietin (THPO) and FL, had a more pronounced GM progenitor phenotype than Thpo(-/-) mice, establishing a role of FL in THPO-dependent and independent regulation of GM progenitors, of likely significance for myeloid malignancies with Flt3-ITD mutations. (Less)
Bertrand Audoin - One of the best experts on this subject based on the ideXlab platform.
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magnetic resonance study of the influence of tissue damage and cortical reorganization on pasat performance at the Earliest Stage of multiple sclerosis
Human Brain Mapping, 2005Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the Earliest Stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the Earliest Stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT.
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modulation of effective connectivity inside the working memory network in patients at the Earliest Stage of multiple sclerosis
NeuroImage, 2005Co-Authors: M Au V Duong, Bertrand Audoin, Danielle Ibarrola, S Confortgouny, Irina Malikova, Jean Pelletier, Kader Boulanouar, S Treseras, P Celsis, P J CozzoneAbstract:fMRI and structural equation modeling (SEM) were used to study effective connectivity inside the working memory network in patients at the Earliest Stage of multiple sclerosis (MS), while performing paced auditory serial addition test (PASAT), a sensitive task to reveal subtle cognitive impairments related to working memory and information speed processing. The path model used for SEM included bilateral connections between left and right BA 46, left and right BA 40, left and right anterior cingulate cortex (ACC), left BA 44 and left BA 40, right BA 44 and right BA 40, and unidirectional ipsilateral connections from BA 46 to BA 44, from ACC to BA 46, and from ACC to BA 44. Experimental data from the two groups fit accurately the working memory model, in patients [χ(20)2 = 13, P = 0.877] as well as in controls [χ(20)2 = 13.54, P = 0.853]. The omnibus test indicated a significant difference of model fits in patients and in controls [χ(40)2 = 160.07, P < 0.0001]. Connectivity strengths from right BA 46 to left BA 46, from left ACC to left BA 46 were lower in patients than in controls, and higher from right ACC to right BA 46, from left to right and from right to left ACC (stacked model). Effective connectivity inside the working memory network appears altered in patients at the Earliest Stage of MS. Modulation of effective connectivity is present in patients inside the executive subsystems of working memory, and could be related to adaptive cognitive control processes that may limit the clinical manifestation of MS.
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local tissue damage assessed with statistical mapping analysis of brain magnetization transfer ratio relationship with functional status of patients in the Earliest Stage of multiple sclerosis
American Journal of Neuroradiology, 2005Co-Authors: Jeanphilippe Ranjeva, Bertrand Audoin, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, D Ibarrola, Jean PelletierAbstract:BACKGROUND AND PURPOSE: In the early Stage of Multiple Sclerosis (MS), conventional MR imaging parameters such as T2 lesion load fail to explain the clinical status of patients. In the present work, we aimed to determine the ability of magnification transfer imaging to better reflect the relationship between local tissue damage and functional status of MS patients. METHODS: We performed a comparative statistical mapping analysis on brain tissue magnetization transfer ratio (MTR) data measured in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) and 18 matched control subjects. RESULTS: In the patients with CISSMS, a pattern of significant low MTR values was observed in the white matter, corpus callosum, bilateral occipitofrontal fascicles, right fornix, right parietal white matter, external capsule, right superior longitudinal fasciculus (SLF), right inferior longitudinal fasciculus, optica radiata, parietal white matter, right cingulum, gray matter, bilateral thalamus, bilateral caudate, right insula, and left Brodmann area (BA) 8. No correlation was found between local MTR decrease and Expanded Disability Status Scale score. Significant correlations between MTR and MS Functional Composite scores (Spearman rank test, P <.05) were observed in the left BA40, right SLF, right frontal white matter, splenium, and anterior corpus callosum. Local MTR values correlated with Paced Auditory Serial Addition Test scores in the left BA40, right BA4, right SLF, and splenium. CONCLUSION: Statistical mapping analysis of brain MTR data provides valuable information on the relationship between the location of brain tissue damage and its functional impact in patients with MS, even in the Earliest Stage of the disease.
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Magnetic resonance study of the influence of tissue damage and cortical reorganization on PASAT performance at the Earliest Stage of multiple sclerosis.
Human Brain Mapping, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, Irina Malikova, My Van Au Duong, Elisabeth Soulier, P Viout, Sylviane Confort-gouny, André Ali-chérif, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the Earliest Stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the Earliest Stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT. Hum. Brain Mapping 24:216–228, 2005. © 2004 Wiley-Liss, Inc.
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voxel based analysis of mtr images a method to locate gray matter abnormalities in patients at the Earliest Stage of multiple sclerosis
Journal of Magnetic Resonance Imaging, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, Jean PelletierAbstract:Purpose To determine whether voxel-based analysis of magnetization transfer ratio (MTR) maps can provide evidence of a coherent pattern of gray matter (GM) macroscopic and microscopic tissue damage in patients at the Earliest Stage of multiple sclerosis (MS). Materials and Methods We acquired GM MTR maps in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS), and 18 sex- and age-matched healthy controls. We evaluated the clinical status of the patients using the MS functional composite score and the expanded disability status scale. A two-sample t-test (P < 0.0001, k = 20, uncorrected for height threshold) was used to compare GM MTR maps from patients and controls on a voxel-by-voxel basis. We then extracted data from regions with t-values above the statistical threshold to verify the significance of differences using a nonparametric Mann-Whitney U-test. Results A between-groups comparison of GM maps revealed large abnormalities in the basal ganglia, including the bilateral thalamus, bilateral lenticular nucleus, bilateral head of caudate, and protuberance, and smaller abnormalities in the right insula, right BA 4, and left BA 40. The MTR measured in the left caudate and right insula was inversely correlated with duration following the first clinical event. Conclusion These results suggest that although MS is a multifocal demyelinating disease that affects white matter (WM), a pattern of tissue damage is present inside the GM involving predominantly basal ganglia at the Earliest Stage of the disease. J. Magn. Reson. Imaging 2004;20:765–771. © 2004 Wiley-Liss, Inc.
Irina Malikova - One of the best experts on this subject based on the ideXlab platform.
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magnetic resonance study of the influence of tissue damage and cortical reorganization on pasat performance at the Earliest Stage of multiple sclerosis
Human Brain Mapping, 2005Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the Earliest Stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the Earliest Stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT.
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modulation of effective connectivity inside the working memory network in patients at the Earliest Stage of multiple sclerosis
NeuroImage, 2005Co-Authors: M Au V Duong, Bertrand Audoin, Danielle Ibarrola, S Confortgouny, Irina Malikova, Jean Pelletier, Kader Boulanouar, S Treseras, P Celsis, P J CozzoneAbstract:fMRI and structural equation modeling (SEM) were used to study effective connectivity inside the working memory network in patients at the Earliest Stage of multiple sclerosis (MS), while performing paced auditory serial addition test (PASAT), a sensitive task to reveal subtle cognitive impairments related to working memory and information speed processing. The path model used for SEM included bilateral connections between left and right BA 46, left and right BA 40, left and right anterior cingulate cortex (ACC), left BA 44 and left BA 40, right BA 44 and right BA 40, and unidirectional ipsilateral connections from BA 46 to BA 44, from ACC to BA 46, and from ACC to BA 44. Experimental data from the two groups fit accurately the working memory model, in patients [χ(20)2 = 13, P = 0.877] as well as in controls [χ(20)2 = 13.54, P = 0.853]. The omnibus test indicated a significant difference of model fits in patients and in controls [χ(40)2 = 160.07, P < 0.0001]. Connectivity strengths from right BA 46 to left BA 46, from left ACC to left BA 46 were lower in patients than in controls, and higher from right ACC to right BA 46, from left to right and from right to left ACC (stacked model). Effective connectivity inside the working memory network appears altered in patients at the Earliest Stage of MS. Modulation of effective connectivity is present in patients inside the executive subsystems of working memory, and could be related to adaptive cognitive control processes that may limit the clinical manifestation of MS.
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local tissue damage assessed with statistical mapping analysis of brain magnetization transfer ratio relationship with functional status of patients in the Earliest Stage of multiple sclerosis
American Journal of Neuroradiology, 2005Co-Authors: Jeanphilippe Ranjeva, Bertrand Audoin, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, D Ibarrola, Jean PelletierAbstract:BACKGROUND AND PURPOSE: In the early Stage of Multiple Sclerosis (MS), conventional MR imaging parameters such as T2 lesion load fail to explain the clinical status of patients. In the present work, we aimed to determine the ability of magnification transfer imaging to better reflect the relationship between local tissue damage and functional status of MS patients. METHODS: We performed a comparative statistical mapping analysis on brain tissue magnetization transfer ratio (MTR) data measured in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) and 18 matched control subjects. RESULTS: In the patients with CISSMS, a pattern of significant low MTR values was observed in the white matter, corpus callosum, bilateral occipitofrontal fascicles, right fornix, right parietal white matter, external capsule, right superior longitudinal fasciculus (SLF), right inferior longitudinal fasciculus, optica radiata, parietal white matter, right cingulum, gray matter, bilateral thalamus, bilateral caudate, right insula, and left Brodmann area (BA) 8. No correlation was found between local MTR decrease and Expanded Disability Status Scale score. Significant correlations between MTR and MS Functional Composite scores (Spearman rank test, P <.05) were observed in the left BA40, right SLF, right frontal white matter, splenium, and anterior corpus callosum. Local MTR values correlated with Paced Auditory Serial Addition Test scores in the left BA40, right BA4, right SLF, and splenium. CONCLUSION: Statistical mapping analysis of brain MTR data provides valuable information on the relationship between the location of brain tissue damage and its functional impact in patients with MS, even in the Earliest Stage of the disease.
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Magnetic resonance study of the influence of tissue damage and cortical reorganization on PASAT performance at the Earliest Stage of multiple sclerosis.
Human Brain Mapping, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, Irina Malikova, My Van Au Duong, Elisabeth Soulier, P Viout, Sylviane Confort-gouny, André Ali-chérif, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the Earliest Stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the Earliest Stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT. Hum. Brain Mapping 24:216–228, 2005. © 2004 Wiley-Liss, Inc.
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voxel based analysis of mtr images a method to locate gray matter abnormalities in patients at the Earliest Stage of multiple sclerosis
Journal of Magnetic Resonance Imaging, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, Jean PelletierAbstract:Purpose To determine whether voxel-based analysis of magnetization transfer ratio (MTR) maps can provide evidence of a coherent pattern of gray matter (GM) macroscopic and microscopic tissue damage in patients at the Earliest Stage of multiple sclerosis (MS). Materials and Methods We acquired GM MTR maps in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS), and 18 sex- and age-matched healthy controls. We evaluated the clinical status of the patients using the MS functional composite score and the expanded disability status scale. A two-sample t-test (P < 0.0001, k = 20, uncorrected for height threshold) was used to compare GM MTR maps from patients and controls on a voxel-by-voxel basis. We then extracted data from regions with t-values above the statistical threshold to verify the significance of differences using a nonparametric Mann-Whitney U-test. Results A between-groups comparison of GM maps revealed large abnormalities in the basal ganglia, including the bilateral thalamus, bilateral lenticular nucleus, bilateral head of caudate, and protuberance, and smaller abnormalities in the right insula, right BA 4, and left BA 40. The MTR measured in the left caudate and right insula was inversely correlated with duration following the first clinical event. Conclusion These results suggest that although MS is a multifocal demyelinating disease that affects white matter (WM), a pattern of tissue damage is present inside the GM involving predominantly basal ganglia at the Earliest Stage of the disease. J. Magn. Reson. Imaging 2004;20:765–771. © 2004 Wiley-Liss, Inc.
S Confortgouny - One of the best experts on this subject based on the ideXlab platform.
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magnetic resonance study of the influence of tissue damage and cortical reorganization on pasat performance at the Earliest Stage of multiple sclerosis
Human Brain Mapping, 2005Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, Jean PelletierAbstract:We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the Earliest Stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the Earliest Stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT.
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modulation of effective connectivity inside the working memory network in patients at the Earliest Stage of multiple sclerosis
NeuroImage, 2005Co-Authors: M Au V Duong, Bertrand Audoin, Danielle Ibarrola, S Confortgouny, Irina Malikova, Jean Pelletier, Kader Boulanouar, S Treseras, P Celsis, P J CozzoneAbstract:fMRI and structural equation modeling (SEM) were used to study effective connectivity inside the working memory network in patients at the Earliest Stage of multiple sclerosis (MS), while performing paced auditory serial addition test (PASAT), a sensitive task to reveal subtle cognitive impairments related to working memory and information speed processing. The path model used for SEM included bilateral connections between left and right BA 46, left and right BA 40, left and right anterior cingulate cortex (ACC), left BA 44 and left BA 40, right BA 44 and right BA 40, and unidirectional ipsilateral connections from BA 46 to BA 44, from ACC to BA 46, and from ACC to BA 44. Experimental data from the two groups fit accurately the working memory model, in patients [χ(20)2 = 13, P = 0.877] as well as in controls [χ(20)2 = 13.54, P = 0.853]. The omnibus test indicated a significant difference of model fits in patients and in controls [χ(40)2 = 160.07, P < 0.0001]. Connectivity strengths from right BA 46 to left BA 46, from left ACC to left BA 46 were lower in patients than in controls, and higher from right ACC to right BA 46, from left to right and from right to left ACC (stacked model). Effective connectivity inside the working memory network appears altered in patients at the Earliest Stage of MS. Modulation of effective connectivity is present in patients inside the executive subsystems of working memory, and could be related to adaptive cognitive control processes that may limit the clinical manifestation of MS.
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local tissue damage assessed with statistical mapping analysis of brain magnetization transfer ratio relationship with functional status of patients in the Earliest Stage of multiple sclerosis
American Journal of Neuroradiology, 2005Co-Authors: Jeanphilippe Ranjeva, Bertrand Audoin, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, D Ibarrola, Jean PelletierAbstract:BACKGROUND AND PURPOSE: In the early Stage of Multiple Sclerosis (MS), conventional MR imaging parameters such as T2 lesion load fail to explain the clinical status of patients. In the present work, we aimed to determine the ability of magnification transfer imaging to better reflect the relationship between local tissue damage and functional status of MS patients. METHODS: We performed a comparative statistical mapping analysis on brain tissue magnetization transfer ratio (MTR) data measured in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) and 18 matched control subjects. RESULTS: In the patients with CISSMS, a pattern of significant low MTR values was observed in the white matter, corpus callosum, bilateral occipitofrontal fascicles, right fornix, right parietal white matter, external capsule, right superior longitudinal fasciculus (SLF), right inferior longitudinal fasciculus, optica radiata, parietal white matter, right cingulum, gray matter, bilateral thalamus, bilateral caudate, right insula, and left Brodmann area (BA) 8. No correlation was found between local MTR decrease and Expanded Disability Status Scale score. Significant correlations between MTR and MS Functional Composite scores (Spearman rank test, P <.05) were observed in the left BA40, right SLF, right frontal white matter, splenium, and anterior corpus callosum. Local MTR values correlated with Paced Auditory Serial Addition Test scores in the left BA40, right BA4, right SLF, and splenium. CONCLUSION: Statistical mapping analysis of brain MTR data provides valuable information on the relationship between the location of brain tissue damage and its functional impact in patients with MS, even in the Earliest Stage of the disease.
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voxel based analysis of mtr images a method to locate gray matter abnormalities in patients at the Earliest Stage of multiple sclerosis
Journal of Magnetic Resonance Imaging, 2004Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, My Van Au Duong, Elisabeth Soulier, P Viout, Jean PelletierAbstract:Purpose To determine whether voxel-based analysis of magnetization transfer ratio (MTR) maps can provide evidence of a coherent pattern of gray matter (GM) macroscopic and microscopic tissue damage in patients at the Earliest Stage of multiple sclerosis (MS). Materials and Methods We acquired GM MTR maps in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS), and 18 sex- and age-matched healthy controls. We evaluated the clinical status of the patients using the MS functional composite score and the expanded disability status scale. A two-sample t-test (P < 0.0001, k = 20, uncorrected for height threshold) was used to compare GM MTR maps from patients and controls on a voxel-by-voxel basis. We then extracted data from regions with t-values above the statistical threshold to verify the significance of differences using a nonparametric Mann-Whitney U-test. Results A between-groups comparison of GM maps revealed large abnormalities in the basal ganglia, including the bilateral thalamus, bilateral lenticular nucleus, bilateral head of caudate, and protuberance, and smaller abnormalities in the right insula, right BA 4, and left BA 40. The MTR measured in the left caudate and right insula was inversely correlated with duration following the first clinical event. Conclusion These results suggest that although MS is a multifocal demyelinating disease that affects white matter (WM), a pattern of tissue damage is present inside the GM involving predominantly basal ganglia at the Earliest Stage of the disease. J. Magn. Reson. Imaging 2004;20:765–771. © 2004 Wiley-Liss, Inc.
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compensatory cortical activation observed by fmri during a cognitive task at the Earliest Stage of ms
Human Brain Mapping, 2003Co-Authors: Bertrand Audoin, Danielle Ibarrola, Jeanphilippe Ranjeva, S Confortgouny, Irina Malikova, Andre Alicherif, Jean Pelletier, Patrick J CozzoneAbstract:Recent functional magnetic resonance imaging (fMRI) studies have suggested that functional cortical changes seen in patients with early relapsing-remitting multiple sclerosis (MS) can have an adaptive role to limit the clinical impact of tissue injury. To determine whether cortical reorganization occurs during high cognitive processes at the Earliest Stage of multiple sclerosis (MS), we performed an fMRI experiment using the conventional Paced Auditory Serial Addition Test (PASAT) as paradigm in a population of ten patients with clinically isolated syndrome suggestive of multiple sclerosis (CISSMS). At the time of the fMRI exploration, mean disease duration was 6.8 3.3 months. We compared these results to those obtained in a group of ten education-, age-, and sex-matched healthy controls. Subjects were explored on a 1.5 T MRI system using single-shot gradient-echo EPI sequence. Performances of the two groups during PASAT recorded inside the MR scanner were not different. Statistical assessment of brain activation was based on the random effect analysis (between-group analysis two-sample t-test P 0.005 confirmed by individual analyses performed in the surviving regions P 0.05 Mann Whitney U-test). Compared to controls, patients showed significantly greater activation in the right frontopolar cortex, the bilateral lateral prefrontal cortices, and the right cerebel- lum. Healthy controls did not show greater activation compared to CISSMS patients. The present study argues in favor of the existence of compensatory cortical activations at the Earliest Stage of MS mainly located in regions involved in executive processing in patients performing PASAT. It also suggests that fMRI can evidence the active processes of neuroplasticity contributing to mask the clinical cognitive expression of brain pathology at the Earliest Stage of MS. Hum. Brain Mapping 20:51-58, 2003. © 2003 Wiley-Liss, Inc.
