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Key Words
- MR Physicist
- Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS)
- In vivo multimodal MRI/MRS (human and small animals)
- MR instrumentation



Journal Article

  • Boutière, C, Rey, C, Zaaraoui, W, Le Troter, A, Rico, A, Crespy, L, Achard, S, Reuter, F, Pariollaud, F, Wirsich, J, Asquinazi, P, Confort-Gouny, S, Soulier, E, Guye, M, Pelletier, J, Ranjeva, J-P & Audoin, B 2017, “Improvement of spasticity following intermittent theta burst stimulation in multiple sclerosis is associated with modulation of resting-state functional connectivity of the primary motor cortices”, Multiple Sclerosis (Houndmills, Basingstoke, England), vol. 23, no. 6, p. 855-863.
    Résumé : BACKGROUND: Intermittent theta burst stimulation (iTBS) of the primary motor cortex improves transiently lower limbs spasticity in multiple sclerosis (MS). However, the cerebral mechanisms underlying this effect have never been investigated. OBJECTIVE: To assess whether modulation of spasticity induced by iTBS is underlined by functional reorganization of the primary motor cortices. METHODS: A total of 17 patients with MS suffering from lower limbs spasticity were randomized to receive real iTBS or sham iTBS during the first half of a 5-week indoor rehabilitation programme. Spasticity was assessed using the Modified Ashworth Scale and the Visual Analogue Scale at baseline, after the stimulation session and at the end of the rehabilitation programme. Resting-state functional magnetic resonance imaging (fMRI) was performed at the three time points, and brain functional networks topology was analysed using graph-theoretical approach. RESULTS: At the end of stimulation, improvement of spasticity was greater in real iTBS group than in sham iTBS group ( p = 0.026). iTBS had a significant effect on the balance of the connectivity degree between the stimulated and the homologous primary motor cortex ( p = 0.005). Changes in inter-hemispheric balance were correlated with improvement of spasticity (rho = 0.56, p = 0.015). CONCLUSION: This longitudinal resting-state fMRI study evidences that functional reorganization of the primary motor cortices may underlie the effect of iTBS on spasticity in MS.

  • Doche, E, Lecocq, A, Maarouf, A, Duhamel, G, Soulier, E, Confort-Gouny, S, Rico, A, Guye, M, Audoin, B, Pelletier, J, Ranjeva, J-P & Zaaraoui, W 2017, “Hypoperfusion of the thalamus is associated with disability in relapsing remitting multiple sclerosis”, Journal of Neuroradiology. Journal De Neuroradiologie, vol. 44, no. 2, p. 158-164.
    Résumé : BACKGROUND: While gray matter (GM) perfusion abnormalities have been evidenced in multiple sclerosis (MS) patients, the relationships with disability still remain unclear. Considering that atrophy is known to impact on perfusion, we aimed to assess perfusion abnormalities in GM of MS patients, outside atrophic regions and investigate relationships with disability. METHODS: Brain perfusion of 23 relapsing remitting MS patients and 16 matched healthy subjects were assessed at 3T using the pseudo-continuous arterial spin labeling magnetic resonance imaging technique. In order to locate potential GM perfusion abnormalities in regions spared by atrophy, we combined voxelwise comparisons of GM cerebral blood flow (CBF) maps (cortex and deep GM) (P<0.005, FWE-corrected) and voxel-based-morphometry analysis (P<0.005, FDR-corrected) to exclude atrophic regions. Disability was assessed using the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Functional Composite score (MSFC). RESULTS: In patients, significant GM hypoperfusion outside atrophic regions was depicted only in bilateral thalami. No other cluster was found to be hypoperfused compared to controls. Perfusion of thalami was correlated to MSFC (P=0.011, rho=0.523). A trend of correlation was found between perfusion of thalami and EDSS (P=0.061, rho=-0.396). CONCLUSION: In relapsing remitting MS, perfusion abnormalities in thalamic regions contribute to disability. These findings suggest that functional impairments of thalami, representing a major brain hub, may disturb various cerebral functions even before structural damage.

  • Donadieu, M, Le Fur, Y, Maarouf, A, Gherib, S, Ridley, B, Pini, L, Rapacchi, S, Confort-Gouny, S, Guye, M, Schad, LR, Maudsley, AA, Pelletier, J, Audoin, B, Zaaraoui, W & Ranjeva, J-P 2017, “Metabolic counterparts of sodium accumulation in multiple sclerosis: A whole brain (23)Na-MRI and fast (1)H-MRSI study”, Multiple Sclerosis (Houndmills, Basingstoke, England), p. 1352458517736146.
    Résumé : BACKGROUND: Increase of brain total sodium concentrations (TSC) is present in multiple sclerosis (MS), but its pathological involvement has not been assessed yet. OBJECTIVE: To determine in vivo the metabolic counterpart of brain sodium accumulation. MATERIALS/METHODS: Whole brain (23)Na-MR imaging and 3D-(1)H-EPSI data were collected in 21 relapsing-remitting multiple sclerosis (RRMS) patients and 20 volunteers. Metabolites and sodium levels were extracted from several regions of grey matter (GM), normal-appearing white matter (NAWM) and white matter (WM) T2 lesions. Metabolic and ionic levels expressed as Z-scores have been averaged over the different compartments and used to explain sodium accumulations through stepwise regression models. RESULTS: MS patients showed significant (23)Na accumulations with lower choline and glutamate-glutamine (Glx) levels in GM; (23)Na accumulations with lower N-acetyl aspartate (NAA), Glx levels and higher Myo-Inositol (m-Ins) in NAWM; and higher (23)Na, m-Ins levels with lower NAA in WM T2 lesions. Regression models showed associations of TSC increase with reduced NAA in GM, NAWM and T2 lesions, as well as higher total-creatine, and smaller decrease of m-Ins in T2 lesions. GM Glx levels were associated with clinical scores. CONCLUSION: Increase of TSC in RRMS is mainly related to neuronal mitochondrial dysfunction while dysfunction of neuro-glial interactions within GM is linked to clinical scores.
    Mots-clés : 23Na-MRI, crmbm, demyelination, MRSI, Multiple sclerosis, neurodegeneration, snc, stepwise regression.

  • Maarouf, A, Audoin, B, Pariollaud, F, Gherib, S, Rico, A, Soulier, E, Confort-Gouny, S, Guye, M, Schad, L, Pelletier, J, Ranjeva, J-P & Zaaraoui, W 2017, “Increased total sodium concentration in gray matter better explains cognition than atrophy in MS”, Neurology, vol. 88, no. 3, p. 289-295, viewed 18August,2017, .
    Résumé : Objective: To investigate whether brain total sodium accumulation assessed by 23Na MRI is associated with cognitive deficit in relapsing-remitting multiple sclerosis (RRMS). Methods: Eighty-nine participants were enrolled in the study (58 patients with RRMS with a disease duration ≤10 years and 31 matched healthy controls). Patients were classified as cognitively impaired if they failed at least 2 tasks on the Brief Repeatable Battery. MRI was performed at 3T using 23Na MRI to obtain total sodium concentration (TSC) in the different brain compartments (lesions, normal-appearing white matter [NAWM], gray matter [GM]) and 1H- magnetization-prepared rapid gradient echo to assess GM atrophy (GM fraction). Results: The mean disease duration was 3.1 years and the median Expanded Disability Status Scale score was 1 (range 0–4.5). Thirty-seven patients were classified as cognitively preserved and 21 as cognitively impaired. TSC was increased in GM and NAWM in cognitively impaired patients compared to cognitively preserved patients and healthy controls. Voxel-wise analysis demonstrated that sodium accumulation was mainly located in the neocortex in cognitively impaired patients. Regression analysis evidenced than the 2 best independent predictors of cognitive impairment were GM TSC and age. Receiver operating characteristic analyses demonstrated that sensitivity and specificity of the GM TSC to classify patients according to their cognitive status were 76% and 71%, respectively. Conclusions: This study provides 2 main findings. (1) In RRMS, total sodium accumulation in the GM is better associated with cognitive impairment than GM atrophy; and (2) total sodium accumulation in patients with cognitive impairment is mainly located in the neocortex.
    Mots-clés : crmbm, snc.

  • Ridley, B, Marchi, A, Wirsich, J, Soulier, E, Confort-Gouny, S, Schad, L, Bartolomei, F, Ranjeva, J-P, Guye, M & Zaaraoui, W 2017, “Brain sodium MRI in human epilepsy: Disturbances of ionic homeostasis reflect the organization of pathological regions”, NeuroImage, vol. 157, p. 173-183.
    Résumé : In light of technical advancements supporting exploration of MR signals other than (1)H, sodium ((23)Na) has received attention as a marker of ionic homeostasis and cell viability. Here, we evaluate for the first time the possibility that (23)Na-MRI is sensitive to pathological processes occurring in human epilepsy. A normative sample of 27 controls was used to normalize regions of interest (ROIs) from 1424 unique brain locales on quantitative (23)Na-MRI and high-resolution (1)H-MPRAGE images. ROIs were based on intracerebral electrodes in ten patients undergoing epileptic network mapping. The stereo-EEG gold standard was used to define regions as belonging to primarily epileptogenic, secondarily irritative and to non-involved regions. Estimates of total sodium concentration (TSC) on (23)Na-MRI and cerebrospinal fluid (CSF) on (1)H imaging were extracted for each patient ROI, and normalized against the same region in controls. ROIs with disproportionate CSF contributions (ZCSF≥1.96) were excluded. TSC levels were found to be elevated in patients relative to controls except in one patient, who suffered non-convulsive seizures during the scan, in whom we found reduced TSC levels. In the remaining patients, an ANOVA (F1100= 12.37, p<0.0001) revealed a highly significant effect of clinically-defined zones (F1100= 11.13, p<0.0001), with higher normalized TSC in the epileptogenic zone relative to both secondarily irritative (F1100= 11, p=0.0009) and non-involved regions (F1100= 17.8, p<0.0001). We provide the first non-invasive, in vivo evidence of a chronic TSC elevation alongside ZCSF levels within the normative range, associated with the epileptogenic region even during the interictal period in human epilepsy, and the possibility of reduced TSC levels due to seizure. In line with modified homeostatic mechanisms in epilepsy - including altered mechanisms underlying ionic gating, clearance and exchange - we provide the first indication of (23)Na-MRI as an assay of altered sodium concentrations occurring in epilepsy associated with the organization of clinically relevant divisions of pathological cortex.
    Mots-clés : Cortical localisation, crmbm, Epilepsy, Epilepsy surgery, Intracranial EEG, Ionic imaging, snc, Sodium MRI.

  • Wirsich, J, Rey, M, Guye, M, Bénar, C, Lanteaume, L, Ridley, B, Confort-Gouny, S, Cassé-Perrot, C, Soulier, E, Viout, P, Rouby, F, Lefebvre, M-N, Audebert, C, Truillet, R, Jouve, E, Payoux, P, Bartrés-Faz, D, Bordet, R, Richardson, JC, Babiloni, C, Rossini, PM, Micallef, J, Blin, O, Ranjeva, J-P & Pharmacog Consortium, 2017, “Brain Networks are Independently Modulated by Donepezil, Sleep, and Sleep Deprivation”, Brain Topography.
    Résumé : Resting-state connectivity has been widely studied in the healthy and pathological brain. Less well-characterized are the brain networks altered during pharmacological interventions and their possible interaction with vigilance. In the hopes of finding new biomarkers which can be used to identify cortical activity and cognitive processes linked to the effects of drugs to treat neurodegenerative diseases such as Alzheimer's disease, the analysis of networks altered by medication would be particularly interesting. Eleven healthy subjects were recruited in the context of the European Innovative Medicines Initiative 'PharmaCog'. Each underwent five sessions of simultaneous EEG-fMRI in order to investigate the effects of donepezil and memantine before and after sleep deprivation (SD). The SD approach has been previously proposed as a model for cognitive impairment in healthy subjects. By applying network based statistics (NBS), we observed altered brain networks significantly linked to donepezil intake and sleep deprivation. Taking into account the sleep stages extracted from the EEG data we revealed that a network linked to sleep is interacting with sleep deprivation but not with medication intake. We successfully extracted the functional resting-state networks modified by donepezil intake, sleep and SD. We observed donepezil induced whole brain connectivity alterations forming a network separated from the changes induced by sleep and SD, a result which shows the utility of this approach to check for the validity of pharmacological resting-state analysis of the tested medications without the need of taking into account the subject specific vigilance.
    Mots-clés : Donepezil, EEG-fMRI, Functional connectivity, Memantine, Sleep, snc.

  • Wybrecht, D, Reuter, F, Pariollaud, F, Zaaraoui, W, Le Troter, A, Rico, A, Confort-Gouny, S, Soulier, E, Guye, M, Maarouf, A, Ranjeva, J-P, Pelletier, J & Audoin, B 2017, “New brain lesions with no impact on physical disability can impact cognition in early multiple sclerosis: A ten-year longitudinal study”, PloS One, vol. 12, no. 11, p. e0184650.
    Résumé : OBJECTIVE: In early multiple sclerosis, although brain T2 lesions accrual are hallmark of the disease, only weak correlations were found between T2 lesions accrual and EDSS progression, the disability scale commonly used in multiple sclerosis studies. This may be related to the very poor sensitivity of EDSS to cognitive dysfunctions that may occur and progress from the first stage of the disease. In the present study, we aimed to demonstrate that cognitive deficits progress during the first ten years of MS and are significantly impacted by new T2 lesions. METHODS: EDSS and extensive neuropsychological battery (22 measures) exploring memory, attention/speed of information processing and executive functions were assessed at baseline, Year 1 and Year 10 in 26 patients enrolled after their first clinical attack. To limit the bias of test-retest effect, only measures obtained at Year 1 and Year 10 were reported in the analysis. Raw scores of patients were transformed into z-scores using published normative data when available or scores of matched controls. Lesion probability mapping was used to assess the potential relationships between T2 lesions accumulation, cognitive decline and EDSS progression (P<0.05, FWE-corrected). RESULTS: At Year 1, 27% of patients showed attention/speed of information processing deficits, 11.5% executive dysfunction and 11.5% memory impairment. During the follow-up, frequency and severity of executive dysfunction increased (from 11.5% of patients at Year 1 to 42% at Year 10, p<0.01) while no significant changes were evidenced for the other cognitive domains. Median EDSS increased from 0.5 [range: 0-3] at Year 1 to 2.5 [range: 0-6.5] at Year 10 (p<0.001). During the ten-year follow-up, lesions accumulation in the left cerebellum and semi-ovale centers was associated with EDSS progression. In contrast, most lesions accumulation in the frontal, parietal and temporal lobes were associated with cognitive decline but had no effect on EDSS progression. CONCLUSION: The present study provides strong evidence that clinically silent T2 lesions impact cognition in early MS. In daily practice, early prevention of T2 lesions accrual may be useful to limit cognitive decline.
    Mots-clés : crmbm, snc.


Journal Article

  • Donadieu, M, Le Fur, Y, Confort-Gouny, S, Le Troter, A, Guye, M & Ranjeva, J-P 2016, “Evidencing different neurochemical profiles between thalamic nuclei using high resolution 2D-PRESS semi-LASER (1)H-MRSI at 7 T”, Magma (New York, N.Y.), vol. 29, no. 3, p. 491-501.
    Résumé : OBJECTIVE: To demonstrate that high resolution (1)H semi-LASER MRSI acquired at 7 T permits discrimination of metabolic patterns of different thalamic nuclei. MATERIALS AND METHODS: Thirteen right-handed healthy volunteers were explored at 7 T using a high-resolution 2D-semi-LASER (1)H-MRSI sequence to determine the relative levels of N-Acetyl Aspartate (NAA), choline (Cho) and creatine-phosphocreatine (Cr) in eight VOIs (volume <0.3 ml) centered on four different thalamic nuclei located on the Oxford thalamic connectivity atlas. Post-processing was done using the CSIAPO software. Chemical shift displacement of metabolites was evaluated on a phantom and correction factors were applied to in vivo data. RESULTS: The global assessment (ANOVA p < 0.05) of the neurochemical profiles (NAA, Cho and Cr levels) with thalamic nuclei and hemispheres as factors showed a significant global effect (F = 11.98, p < 0.0001), with significant effect of nucleus type (p < 0.0001) and hemisphere (p < 0.0001). Post hoc analyses showed differences in neurochemical profiles between the left and the right hemisphere (p < 0.05), and differences in neurochemical profiles between nuclei within each hemisphere (p < 0.05). CONCLUSION: For the first time, using high resolution 2D-PRESS semi-LASER (1)H-MRSI acquired at 7 T, we demonstrated that the neurochemical profiles were different between thalamic nuclei, and that these profiles were dependent on the brain hemisphere.
    Mots-clés : 1H-MRSI, Adult, Analysis of Variance, Aspartic Acid, Brain, Choline, Connectivity atlas, Creatine, crmbm, Female, Healthy Volunteers, Humans, Lasers, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Male, Neurochemical profiles, Neurodegenerative Diseases, Phantoms, Imaging, Phosphocreatine, snc, Software, Spectrophotometry, Thalamic nuclei, Thalamus, Ultra high field, Young Adult.

  • Donadieu, M, Le Fur, Y, Lecocq, A, Maudsley, AA, Gherib, S, Soulier, E, Confort-Gouny, S, Pariollaud, F, Ranjeva, M-P, Pelletier, J, Guye, M, Zaaraoui, W, Audoin, B & Ranjeva, J-P 2016, “Metabolic voxel-based analysis of the complete human brain using fast 3D-MRSI: Proof of concept in multiple sclerosis”, Journal of magnetic resonance imaging: JMRI, vol. 44, no. 2, p. 411-419.
    Résumé : PURPOSE: To detect local metabolic abnormalities over the complete human brain in multiple sclerosis (MS) patients, we used optimized fast volumic echo planar spectroscopic imaging (3D-EPSI). MATERIALS AND METHODS: Weighted mean combination of two 3D-EPSI covering the whole brain acquired at 3T in AC-PC and AC-PC+15° axial planes was performed to obtain high-quality metabolite maps for five metabolites: N-acetyl aspartate (NAA), glutamate+glutamine (Glx), choline (Cho), myo-inositol (m-Ins), and creatine+phosphocreatine (tCr). After spatial normalization, maps from 19 patients suffering from relapsing-remitting MS were compared to 19 matched controls using statistical mapping analyses to determine the topography of metabolic abnormalities. Probabilistic white matter (WM) T2 lesion maps and gray matter (GM) atrophy maps were also generated. RESULTS: Two-group analysis of variance (ANOVA) (SPM8, P < 0.005, false discovery rate [FDR]-corrected P < 0.05 at the cluster level with age and sex as confounding covariates) comparing patients and controls matched for age and sex showed clusters of abnormal metabolite levels with 1) decreased NAA (around -15%) and Glx (around 20%) predominantly in GM within prefrontal cortices, motor cortices, bilateral thalami, and mesial temporal cortices in line with neuronal/neuro-astrocytic dysfunction; 2) increased m-Ins (around + 20%) inside WM T2 lesions and in the normal-appearing WM of temporal-occipital lobes, suggesting glial activation. CONCLUSION: We demonstrate the ability to noninvasively map over the complete brain-from vertex to cerebellum-with a validated sequence, the metabolic abnormalities associated with MS, for characterizing the topography of pathological processes affecting widespread areas of WM and GM and its functional impact. J. Magn. Reson. Imaging 2016;44:411-419.

  • Faivre, A, Robinet, E, Guye, M, Rousseau, C, Maarouf, A, Le Troter, A, Zaaraoui, W, Rico, A, Crespy, L, Soulier, E, Confort-Gouny, S, Pelletier, J, Achard, S, Ranjeva, J-P & Audoin, B 2016, “Depletion of brain functional connectivity enhancement leads to disability progression in multiple sclerosis: A longitudinal resting-state fMRI study”, Multiple Sclerosis (Houndmills, Basingstoke, England), vol. 22, no. 13, p. 1695-1708.
    Résumé : BACKGROUND: The compensatory effect of brain functional connectivity enhancement in relapsing-remitting multiple sclerosis (RRMS) remains controversial. OBJECTIVE: To characterize the relationships between brain functional connectivity changes and disability progression in RRMS. METHODS: Long-range connectivity, short-range connectivity, and density of connections were assessed using graph theoretical analysis of resting-state functional magnetic resonance imaging (fMRI) data acquired in 38 RRMS patients (disease duration: 120 ± 32 months) and 24 controls. All subjects were explored at baseline and all patients and six controls 2 years later. RESULTS: At baseline, levels of long-range and short-range brain functional connectivity were higher in patients compared to controls. During the follow-up, decrease in connections' density was inversely correlated with disability progression. Post-hoc analysis evidenced differential evolution of brain functional connectivity metrics in patients according to their level of disability at baseline: while patients with lowest disability at baseline experienced an increase in all connectivity metrics during the follow-up, patients with higher disability at baseline showed a decrease in the connectivity metrics. In these patients, decrease in the connectivity metrics was associated with disability progression. CONCLUSION: The study provides two main findings: (1) brain functional connectivity enhancement decreases during the disease course after reaching a maximal level, and (2) decrease in brain functional connectivity enhancement participates in disability progression.

  • Koob, M, Girard, N, Ghattas, B, Fellah, S, Confort-Gouny, S, Figarella-Branger, D & Scavarda, D 2016, “The diagnostic accuracy of multiparametric MRI to determine pediatric brain tumor grades and types”, Journal of Neuro-Oncology, vol. 127, no. 2, p. 345-353.
    Résumé : Childhood brain tumors show great histological variability. The goal of this retrospective study was to assess the diagnostic accuracy of multimodal MR imaging (diffusion, perfusion, MR spectroscopy) in the distinction of pediatric brain tumor grades and types. Seventy-six patients (range 1 month to 18 years) with brain tumors underwent multimodal MR imaging. Tumors were categorized by grade (I-IV) and by histological type (A-H). Multivariate statistical analysis was performed to evaluate the diagnostic accuracy of single and combined MR modalities, and of single imaging parameters to distinguish the different groups. The highest diagnostic accuracy for tumor grading was obtained with diffusion-perfusion (73.24 %) and for tumor typing with diffusion-perfusion-MR spectroscopy (55.76 %). The best diagnostic accuracy was obtained for tumor grading in I and IV and for tumor typing in embryonal tumor and pilocytic astrocytoma. Poor accuracy was seen in other grades and types. ADC and rADC were the best parameters for tumor grading and typing followed by choline level with an intermediate echo time, CBV for grading and Tmax for typing. Multiparametric MR imaging can be accurate in determining tumor grades (primarily grades I and IV) and types (mainly pilocytic astrocytomas and embryonal tumors) in children.
    Mots-clés : Brain Neoplasms, Child, crmbm, Diffusion Magnetic Resonance Imaging, Magnetic Resonance Angiography, Magnetic Resonance Spectroscopy, snc.


Journal Article

  • Jubeau, M, LE Fur, Y, Duhamel, G, Wegrzyk, J, Confort-Gouny, S, Vilmen, C, Cozzone, PJ, Mattei, JP, Bendahan, D & Gondin, J 2015, “Localized metabolic and t2 changes induced by voluntary and evoked contractions”, Medicine and Science in Sports and Exercise, vol. 47, no. 5, p. 921-930.
    Résumé : PURPOSE: This study compared the metabolic and activation changes induced by electrically evoked (neuromuscular electrical stimulation (NMES)) and voluntary (VOL) contractions performed at the same submaximal intensity using P chemical shift imaging (CSI) and T2 mapping investigations. METHODS: Fifteen healthy subjects were asked to perform both NMES and VOL protocols with the knee extensors (i.e., 232 isometric contractions at 30% of maximal force) inside a 3-T scanner for two experimental sessions. During the first session, metabolic variations, i.e., phosphocreatine (PCr), inorganic phosphate (Pi), and pH, were recorded using localized P CSI. During a second session, T2 maps of the knee extensors were obtained at rest and immediately after each exercise. Voxels of interest were selected from the directly stimulated vastus lateralis and from the nondirectly stimulated rectus femoris/vastus intermedius muscles. RESULTS: PCr depletion recorded throughout the NMES session was significantly larger in the vastus lateralis as compared with the rectus femoris/vastus intermedius muscles for both conditions (VOL and NMES). A higher occurrence of Pi splitting and a greater acidosis was found during NMES as compared with VOL exercise, illustrating the heterogeneous activation of both slow and fast muscle fibers. T2 changes were greater after NMES as compared with VOL for both muscles but were not necessarily related to the localized metabolic demand. CONCLUSION: We provided direct evidence that the metabolic demand was strongly related to both the exercise modality and the site of stimulation. On the basis of the occurrence of Pi splitting, we suggested that NMES can activate fast muscle fibers even at low force levels.
    Mots-clés : crmbm, msk.

  • Lecocq, A, Le Fur, Y, Maudsley, AA, Le Troter, A, Sheriff, S, Sabati, M, Donadieu, M, Confort-Gouny, S, Cozzone, PJ, Guye, M & Ranjeva, J-P 2015, “Whole-brain quantitative mapping of metabolites using short echo three-dimensional proton MRSI”, Journal of magnetic resonance imaging: JMRI, vol. 42, no. 2, p. 280-289.
    Résumé : BACKGROUND: To improve the extent over which whole brain quantitative three-dimensional (3D) magnetic resonance spectroscopic imaging (MRSI) maps can be obtained and be used to explore brain metabolism in a population of healthy volunteers. METHODS: Two short echo time (20 ms) acquisitions of 3D echo planar spectroscopic imaging at two orientations, one in the anterior commissure-posterior commissure (AC-PC) plane and the second tilted in the AC-PC +15° plane were obtained at 3 Tesla in a group of 10 healthy volunteers. B1 (+) , B1 (-) , and B0 correction procedures and normalization of metabolite signals with quantitative water proton density measurements were performed. A combination of the two spatially normalized 3D-MRSI, using a weighted mean based on the pixel wise standard deviation metabolic maps of each orientation obtained from the whole group, provided metabolite maps for each subject allowing regional metabolic profiles of all parcels of the automated anatomical labeling (AAL) atlas to be obtained. RESULTS: The combined metabolite maps derived from the two acquisitions reduced the regional intersubject variance. The numbers of AAL regions showing N-acetyl aspartate (NAA) SD/Mean ratios lower than 30% increased from 17 in the AC-PC orientation and 41 in the AC-PC+15° orientation, to a value of 76 regions of 116 for the combined NAA maps. Quantitatively, regional differences in absolute metabolite concentrations (mM) over the whole brain were depicted such as in the GM of frontal lobes (cNAA  = 10.03 + 1.71; cCho  = 1.78 ± 0.55; cCr  = 7.29 ± 1.69; cmIns  = 5.30 ± 2.67) and in cerebellum (cNAA  = 5.28 ± 1.77; cCho  = 1.60 ± 0.41; cCr  = 6.95 ± 2.15; cmIns  = 3.60 ± 0.74). CONCLUSION: A double-angulation acquisition enables improved metabolic characterization over a wide volume of the brain. J. Magn. Reson. Imaging 2015;42:280-289.
    Mots-clés : crmbm, snc.

  • Maarouf, A, Ferré, J-C, Zaaraoui, W, Le Troter, A, Bannier, E, Berry, I, Guye, M, Pierot, L, Barillot, C, Pelletier, J, Tourbah, A, Edan, G, Audoin, B & Ranjeva, J-P 2015, “Ultra-small superparamagnetic iron oxide enhancement is associated with higher loss of brain tissue structure in clinically isolated syndrome”, Multiple Sclerosis (Houndmills, Basingstoke, England).
    Résumé : BACKGROUND: Macrophages are important components of inflammatory processes in multiple sclerosis, closely linked to axonal loss, and can now be observed in vivo using ultra-small superparamagnetic iron oxide (USPIO). In the present 1-year longitudinal study, we aimed to determine the prevalence and the impact on tissue injury of macrophage infiltration in patients after the first clinical event of multiple sclerosis. METHODS: Thirty-five patients, 32 years mean age, were imaged in a mean of 66 days after their first event using conventional magnetic resonance imaging, gadolinium (Gd) to probe blood-brain barrier integrity, USPIO to study macrophage infiltration and magnetization transfer ratio (MTR) to assess tissue structure integrity. Statistics were performed using two-group repeated-measures ANOVA. Any patient received treatment at baseline. RESULTS: At baseline, patients showed 17 USPIO-positive lesions reflecting infiltration of macrophages present from the onset. This infiltration was associated with local higher loss of tissue structure as emphasized by significant lower MTRnorm values (p<0.03) in USPIO(+)/Gd(+) lesions (n=16; MTRnormUSPIO(+)/Gd(+)=0.78 at baseline, MTRnormUSPIO(+)/Gd(+)=0.81 at M12) relative to USPIO(-)/Gd(+) lesions (n=67; MTRnormUSPIO(-)/Gd(+)=0.82 at baseline, MTRnormUSPIO(-)/Gd(+)=0.85 at M12). No interaction in MTR values was observed during the 12 months follow-up (lesion type × time). CONCLUSION: Infiltration of activated macrophages evidenced by USPIO enhancement, is present at the onset of multiple sclerosis and is associated with higher and persistent local loss of tissue structure. Macrophage infiltration affects more tissue structure while tissue recovery during the following year has a similar pattern for USPIO and Gd-enhanced lesions, leading to relative higher persistent local loss of tissue structure in lesions showing USPIO enhancement at baseline.

  • Ridley, BGY, Rousseau, C, Wirsich, J, Le Troter, A, Soulier, E, Confort-Gouny, S, Bartolomei, F, Ranjeva, J-P, Achard, S & Guye, M 2015, “Nodal approach reveals differential impact of lateralized focal epilepsies on hub reorganization”, NeuroImage, vol. 118, p. 39-48.
    Résumé : The impact of the hemisphere affected by impairment in models of network disease is not fully understood. Among such models, focal epilepsies are characterised by recurrent seizures generated in epileptogenic areas also responsible for wider network dysfunction between seizures. Previous work focusing on functional connectivity within circumscribed networks suggests a divergence of network integrity and compensatory capacity between epilepsies as a function of the laterality of seizure onset. We evaluated the ability of complex network theory to reveal changes in focal epilepsy in global and nodal parameters using graph theoretical analysis of functional connectivity data obtained with resting-state fMRI. Graphs of functional connectivity networks were derived from 19 right and 13 left focal epilepsy patients and 15 controls. Topological metrics (degree, local efficiency, global efficiency and modularity) were computed for a whole-brain, atlas-defined network. We also calculated a hub disruption index for each graph metric, measuring the capacity of the brain network to demonstrate increased connectivity in some nodes for decreased connectivity in others. Our data demonstrate that the patient group as a whole is characterised by network-wide pattern of reorganization, even while global parameters fail to distinguish between groups. Furthermore, multiple metrics indicate that epilepsies with differently lateralized epileptic networks are asymmetric in their burden on functional brain networks; with left epilepsy patients being characterised by reduced efficiency and modularity, while in right epilepsy patients we provide the first evidence that functional brain networks are characterised by enhanced connectivity and efficiency at some nodes whereas reduced in others.
    Mots-clés : crmbm, Epilepsy, Functional connectivity, graph theory, Hemispheric asymmetry, Network modelling, resting-state, snc.


Journal Article

  • Gour, N, Felician, O, Didic, M, Koric, L, Gueriot, C, Chanoine, V, Confort-Gouny, S, Guye, M, Ceccaldi, M & Ranjeva, JP 2014, “Functional connectivity changes differ in early and late-onset alzheimer's disease”, Human Brain Mapping, vol. 35, no. 7, p. 2978-2994, viewed 29October,2014, .
    Résumé : At a similar stage, patients with early onset Alzheimer's disease (EOAD) have greater neocortical but less medial temporal lobe dysfunction and atrophy than the late-onset form of the disease (LOAD). Whether the organization of neural networks also differs has never been investigated. This study aims at characterizing basal functional connectivity (FC) patterns of EOAD and LOAD in two groups of 14 patients matched for disease duration and severity, relative to age-matched controls. All subjects underwent an extensive neuropsychological assessment. Magnetic resonance imaging was used to quantify atrophy and resting-state FC focusing on : the default mode network (DMN), found impaired in earlier studies on AD, and the anterior temporal network (ATN) and dorso-lateral prefrontal network (DLPFN), respectively involved in declarative memory and executive functions. Patterns of atrophy and cognitive impairment in EOAD and LOAD were in accordance with previous reports. FC within the DMN was similarly decreased in both EOAD and LOAD relative to controls. However, a double-dissociated pattern of FC changes in ATN and DLPFN was found. EOAD exhibited decreased FC in the DLPFN and increased FC in the ATN relative to controls, while the reverse pattern was found in LOAD. In addition, ATN and DLPFN connectivity correlated respectively with memory and executive performances, suggesting that increased FC is here likely to reflect compensatory mechanisms. Thus, large-scale neural network changes in EOAD and LOAD endorse both common features and differences, probably related to a distinct distribution of pathological changes. Hum Brain Mapp 35:2978–2994, 2014. © 2013 Wiley Periodicals, Inc.
    Mots-clés : Age of Onset, Aged, Alzheimer Disease, Atrophy, Brain Mapping, Case-Control Studies, Cerebral Cortex, crmbm, early onset Alzheimer disease, Executive Function, Female, Humans, Image Processing, Computer-Assisted, late onset Alzheimer disease, Magnetic Resonance Imaging, Male, Memory, Mental Status Schedule, Middle Aged, Models, Neurological, Nerve Net, neural networks, Neuropsychological Tests, Oxygen, Statistics as Topic.

  • Grapperon, A-M, Verschueren, A, Duclos, Y, Confort-Gouny, S, Soulier, E, Loundou, AD, Guye, M, Cozzone, PJ, Pouget, J, Ranjeva, J-P & Attarian, S 2014, “Association between structural and functional corticospinal involvement in amyotrophic lateral sclerosis assessed by diffusion tensor MRI and triple stimulation technique”, Muscle & Nerve, vol. 49, no. 4, p. 551-557, viewed 29October,2014, .
    Résumé : Introduction: We investigated the functional and structural integrity of the corticospinal tract (CST) using diffusion tensor imaging (DTI) and the triple stimulation technique (TST) in patients with amyotrophic lateral sclerosis (ALS). Methods: Fourteen patients with ALS, 13 healthy controls (HCs), and 6 patients with lower motor neuron (LMN) syndrome underwent DTI and TST. Results: The mean diffusivity was higher in ALS patients than HCs (P < 0.01). The TST ratio was lower in ALS patients compared with HCs (P < 0.001) and in LMN patients compared with HCs (P < 0.05). The increase in the mean diffusivity was correlated with the decrease in the TST ratio (P < 0.01). Conclusions: Significant correlations exist between the DTI and TST results, indicating both structural and functional involvement of the CST in patients with ALS. Muscle Nerve 49:551–557, 2014
    Mots-clés : Adult, Aged, Amyotrophic Lateral Sclerosis, brain MRI, Diffusion Magnetic Resonance Imaging, diffusion tensor imaging, Female, Humans, Male, Middle Aged, Pyramidal Tracts, Transcranial Magnetic Stimulation, triple stimulation technique.

  • Maarouf, A, Audoin, B, Konstandin, S, Rico, A, Soulier, E, Reuter, F, Troter, AL, Confort-Gouny, S, Cozzone, PJ, Guye, M, Schad, LR, Pelletier, J, Ranjeva, J-P & Zaaraoui, W 2014, “Topography of brain sodium accumulation in progressive multiple sclerosis”, Magnetic Resonance Materials in Physics, Biology and Medicine, vol. 27, no. 1, p. 53-62, viewed 30October,2014, .
    Résumé : Object Sodium accumulation is involved in neuronal injury occurring in multiple sclerosis (MS). We aimed to assess sodium accumulation in progressive MS, known to suffer from severe neuronal injury. Materials and methods 3D-23Na-MRI was obtained on a 3T-MR-scanner in 20 progressive MS patients [11 primary-progressive (PPMS) and nine secondary-progressive (SPMS)] and 15 controls. Total sodium concentrations (TSC) within grey matter (GM), normal-appearing white matter (WM) and lesions were extracted. Statistical mapping analyses of TSC abnormalities were also performed. Results Progressive MS patients presented higher GM–TSC values (48.8 ± 3.1 mmol/l wet tissue vol, p < 0.001) and T2lesions-TSC values (50.9 ± 2.2 mmol/l wet tissue vol, p = 0.01) compared to GM and WM of controls. Statistical mapping analysis showed TSC increases in PPMS patients confined to motor and somatosensory cortices, prefrontal cortices, pons and cerebellum. In SPMS, TSC increases were associated with areas involving: primary motor, premotor and somatosensory cortices; prefrontal, cingulate and visual cortices; the corpus callosum, thalami, brainstem and cerebellum. Anterior prefrontal and premotor cortices TSC were correlated with disability. Conclusion Sodium accumulation is present in progressive MS patients, more restricted to the motor system in PPMS and more widespread in SPMS. Local brain sodium accumulation appears as a promising marker to monitor patients with progressive MS.
    Mots-clés : Adult, Aged, Biomedical Engineering, Brain, Brain Mapping, Case-Control Studies, Computer Appl. in Life Sciences, crmbm, Disability, Female, Grey matter, Health Informatics, Humans, Imaging / Radiology, Magnetic Resonance Imaging, Male, Middle Aged, MRI, Multiple sclerosis, Nerve Fibers, Myelinated, Neurons, Progressive multiple sclerosis, Sodium, Solid State Physics.

  • Wirsich, J, Bénar, C, Ranjeva, J-P, Descoins, M, Soulier, E, Le Troter, A, Confort-Gouny, S, Liégeois-Chauvel, C & Guye, M 2014, “Single-trial EEG-informed fMRI reveals spatial dependency of BOLD signal on early and late IC-ERP amplitudes during face recognition”, NeuroImage, vol. 100, p. 325-336, viewed 4August,2014, .
    Résumé : Simultaneous EEG-fMRI has opened up new avenues for improving the spatio-temporal resolution of functional brain studies. However, this method usually suffers from poor EEG quality, especially for evoked potentials (ERPs), due to specific artifacts. As such, the use of EEG-informed fMRI analysis in the context of cognitive studies has particularly focused on optimizing narrow ERP time windows of interest, which ignores the rich diverse temporal information of the EEG signal. Here, we propose to use simultaneous EEG-fMRI to investigate the neural cascade occurring during face recognition in 14 healthy volunteers by using the successive ERP peaks recorded during the cognitive part of this process. N170, N400 and P600 peaks, commonly associated with face recognition, were successfully and reproducibly identified for each trial and each subject by using a group independent component analysis (ICA). For the first time we use this group ICA to extract several independent components (IC) corresponding to the sequence of activation and used single-trial peaks as modulation parameters in a general linear model (GLM) of fMRI data. We obtained an occipital–temporal–frontal stream of BOLD signal modulation, in accordance with the three successive IC-ERPs providing an unprecedented spatio-temporal characterization of the whole cognitive process as defined by BOLD signal modulation. By using this approach, the pattern of EEG-informed BOLD modulation provided improved characterization of the network involved than the fMRI-only analysis or the source reconstruction of the three ERPs; the latter techniques showing only two regions in common localized in the occipital lobe.
    Mots-clés : crmbm, Evoked Potentials, Face recognition, ICA, Simultaneous EEG-fMRI, Ventral visual pathway.


Journal Article

  • Fellah, S, Caudal, D, De Paula, AM, Dory-Lautrec, P, Figarella-Branger, D, Chinot, O, Metellus, P, Cozzone, PJ, Confort-Gouny, S, Ghattas, B, Callot, V & Girard, N 2013, “Multimodal MR imaging (diffusion, perfusion, and spectroscopy): is it possible to distinguish oligodendroglial tumor grade and 1p/19q codeletion in the pretherapeutic diagnosis?”, AJNR. American journal of neuroradiology, vol. 34, no. 7, p. 1326-1333.
    Résumé : BACKGROUND AND PURPOSE: Pretherapeutic determination of tumor grade and genotype in grade II and III oligodendroglial tumors is clinically important but is still challenging. Tumor grade and 1p/19q status are currently the 2 most important factors in therapeutic decision making for patients with these tumors. Histopathology and cMRI studies are still limited in some cases. In the present study, we were interested in determining whether the combination of PWI, DWI, and MR spectroscopy could help distinguish oligodendroglial tumors according to their histopathologic grade and genotype. MATERIALS AND METHODS: We retrospectively reviewed 50 adult patients with grade II and III oligodendrogliomas and oligoastrocytomas who had DWI, PWI, and MR spectroscopy at short and long TE data and known 1p/19q status. Univariate analyses and multivariate random forest models were performed to determine which criteria could differentiate between grades and genotypes. RESULTS: ADC, rCBV, rCBF, and rK2 were significantly different between grade II and III oligodendroglial tumors. DWI, PWI, and MR spectroscopy showed no significant difference between tumors with and without 1p/19q loss. Separation between tumor grades and genotypes with cMRI alone showed 31% and 48% misclassification rates, respectively. Multimodal MR imaging helps to determine tumor grade and 1p/19q genotype more accurately (misclassification rates of 17% and 40%, respectively). CONCLUSIONS: Although multimodal investigation of oligodendroglial tumors has a lower contribution to 1p/19q genotyping compared with cMRI alone, it greatly improves the accuracy of grading of these neoplasms. Use of multimodal MR imaging could thus provide valuable information that may assist clinicians in patient preoperative management and treatment decision making.
    Mots-clés : Adolescent, Adult, Aged, Aged, 80 and over, Astrocytoma, Brain Neoplasms, Cerebral Cortex, Chromosomes, Human, Pair 1, Chromosomes, Human, Pair 19, Contrast Media, crmbm, Diagnosis, Differential, Diffusion Magnetic Resonance Imaging, Female, Frontal Lobe, Genotype, Humans, Image Enhancement, Image Processing, Computer-Assisted, Magnetic Resonance Angiography, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Male, Middle Aged, Neoplasm Grading, Oligodendroglioma, Retrospective Studies, Sequence Deletion, Temporal Lobe, Young Adult.


Journal Article

  • Durante, L, Zaaraoui, W, Rico, A, Crespy, L, Wybrecht, D, Faivre, A, Reuter, F, Malikova, I, Pommier, G, Confort-Gouny, S, Cozzone, PJ, Ranjeva, J-P, Pelletier, J, Boucraut, J & Audoin, B 2012, “Intrathecal synthesis of IgM measured after a first demyelinating event suggestive of multiple sclerosis is associated with subsequent MRI brain lesion accrual”, Multiple sclerosis (Houndmills, Basingstoke, England), vol. 18, no. 5, p. 587-591.
    Résumé : BACKGROUND: Previous studies have demonstrated that intrathecal synthesis of IgM is observed in multiple sclerosis (MS) and correlates with a worse disease course. These results suggest that IgM participates in the formation of MS lesions. OBJECTIVE: The aim of the present study was to assess the potential association between the level of intrathecal synthesis of IgM measured after a clinically isolated syndrome (CIS) and the subsequent formation of brain lesions. METHODS: Fifty seven patients with a CIS and a high risk developing MS were enrolled in a longitudinal study. Examination of cerebrospinal fluid was performed after the CIS and included measures of intrathecal IgM and IgG synthesis. Patients were assessed with the same 1.5 Tesla magnetic resonance imaging (MRI) system at baseline and after a mean follow-up period of 49 months (range 36-60). Spearman Rank correlation was used to assess the potential correlations between levels of intrathecal immunoglobulin synthesis and MRI data. RESULTS: The level of intrathecal IgM synthesis was correlated with the number of gadolinium-enhancing lesions at baseline (p = 0.01) and with accrual of brain lesions during the follow-up period (p = 0.02). By taking into account brain sub-regions, we demonstrated that the level of intrathecal IgM synthesis was only correlated with the increased number of lesions in the periventricular regions (p = 0.004). The level of intrathecal IgG synthesis was not correlated with any MRI data. CONCLUSION: The present longitudinal study demonstrates that the level of intrathecal IgM synthesis measured after a CIS is associated with subsequent lesion accrual during the first years of MS. This result emphasizes the involvement of IgM in plaque formation.
    Mots-clés : Adult, Brain, Contrast Media, crmbm, Demyelinating Diseases, Disease Progression, Female, France, Humans, Immunoglobulin M, Longitudinal Studies, Magnetic Resonance Imaging, Male, Middle Aged, Multiple sclerosis, Predictive Value of Tests, Severity of Illness Index, Time Factors, Young Adult.

  • Faivre, A, Rico, A, Zaaraoui, W, Crespy, L, Reuter, F, Wybrecht, D, Soulier, E, Malikova, I, Confort-Gouny, S, Cozzone, PJ, Pelletier, J, Ranjeva, J-P & Audoin, B 2012, “Assessing brain connectivity at rest is clinically relevant in early multiple sclerosis”, Multiple sclerosis (Houndmills, Basingstoke, England), vol. 18, no. 9, p. 1251-1258.
    Résumé : OBJECTIVE: The present study aims to determine the clinical counterpart of brain resting-state networks reorganization recently evidenced in early multiple sclerosis. METHODS: Thirteen patients with early relapsing-remitting multiple sclerosis and 14 matched healthy controls were included in a resting state functional MRI study performed at 3 T. Data were analyzed using group spatial Independent Component Analysis using concatenation approach (FSL 4.1.3) and double regression analyses (SPM5) to extract local and global levels of connectivity inside various resting state networks (RSNs). Differences in global levels of connectivity of each network between patients and controls were assessed using Mann-Whitney U-test. In patients, relationship between clinical data (Expanded Disability Status Scale and Multiple Sclerosis Functional Composite Score - MSFC) and global RSN connectivity were assessed using Spearman rank correlation. RESULTS: Independent component analysis provided eight consistent neuronal networks involved in motor, sensory and cognitive processes. For seven RSNs, the global level of connectivity was significantly increased in patients compared with controls. No significant decrease in RSN connectivity was found in early multiple sclerosis patients. MSFC values were negatively correlated with increased RSN connectivity within the dorsal frontoparietal network (r = -0.811, p = 0.001), the right ventral frontoparietal network (r = - 0.587, p = 0.045) and the prefronto-insular network (r = -0.615, p = 0.033). CONCLUSIONS: This study demonstrates that resting state networks reorganization is strongly associated with disability in early multiple sclerosis. These findings suggest that resting state functional MRI may represent a promising surrogate marker of disease burden.
    Mots-clés : Adult, Analysis of Variance, Brain, Brain Mapping, Case-Control Studies, Cognition, crmbm, Disability Evaluation, Female, Humans, Magnetic Resonance Imaging, Male, Motor Activity, Multiple Sclerosis, Relapsing-Remitting, Nerve Net, Neuropsychological Tests, Predictive Value of Tests, Prognosis, Regression Analysis, Rest, Sensation, Severity of Illness Index, Young Adult.

  • Fellah, S, Callot, V, Viout, P, Confort-Gouny, S, Scavarda, D, Dory-Lautrec, P, Figarella-Branger, D, Cozzone, PJ & Girard, N 2012, “Epileptogenic brain lesions in children: the added-value of combined diffusion imaging and proton MR spectroscopy to the presurgical differential diagnosis”, Child's nervous system: ChNS: official journal of the International Society for Pediatric Neurosurgery, vol. 28, no. 2, p. 273-282.
    Résumé : PURPOSE: Focal cortical dysplasia (FCD), dysembryoplastic neuroepithelial tumors (DNTs), and gangliogliomas (GGs) share many clinical features, and the presurgical differential diagnosis of these lesions using conventional magnetic resonance imaging (MRI) is challenging in some cases. The purpose of this work was thus to evaluate the capacity of diffusion-weighted imaging (DWI) and proton magnetic resonance spectroscopy (MRS) to distinguish each lesion from the others. METHODS: Seventeen children (mean age 9.0 ± 4.7 years), who had been referred for epilepsy associated with a brain tumor and operated, were selected. Preoperative MRI examinations were performed on a 1.5 T system and included anatomical images [T2-weighted, fluid-attenuated inversion recovery (FLAIR) and T1 pre- and post-injection images] as well as DWI and MRS [echo time (TE) = 30 and 135 ms]. Apparent diffusion coefficient (ADC) values were calculated in the lesion and healthy control. MRS relative quantification consisted in normalizing each metabolite by the sum (S) of all metabolites (S(TE=135 ms) = NAA+Cr+Cho; S(TE=30 ms) = NAA+Cr+Cho+Glx+mI). Univariate and multivariate analyses were performed in order to determine which criteria could differentiate the different epileptogenic brain lesions. RESULTS: When taken alone, none of the MRI parameters was able to distinguish each disease from the others. Conventional MRI failed classifying two patients. When adding ADC to the linear discriminant analysis (LDA), one patient was still misclassified. Complete separation of the three groups was possible when combining conventional MRI, diffusion, and MRS either at long or short TE. CONCLUSION: This study shows the added-value of multimodal MRI and MRS in the presurgical diagnosis of epileptogenic brain lesions in children.
    Mots-clés : Adolescent, Brain Diseases, Brain Neoplasms, Child, Child, Preschool, crmbm, Diagnosis, Differential, Diffusion Magnetic Resonance Imaging, Epilepsy, Humans, Infant, Magnetic Resonance Spectroscopy, Malformations of Cortical Development, Malformations of Cortical Development, Group I, Protons.

  • Garcia, C, Lutz, NW, Confort-Gouny, S, Cozzone, PJ, Armand, M & Bernard, M 2012, “Phospholipid fingerprints of milk from different mammalians determined by 31P NMR: towards specific interest in human health”, Food Chemistry, vol. 135, no. 3, p. 1777-1783.
    Résumé : Our objective was to identify and quantify phospholipids in milk from different species (human HM, cow CoM, camel CaM, and mare MM) using an optimised (31)P NMR spectroscopy procedure. The phospholipid fingerprints were species-specific with a broader variety of classes found in HM and MM; HM and CaM were richer in sphingomyelin (78.3 and 117.5μg/ml) and plasmalogens (27.3 and 24μg/ml), possibly important for infant development. Total phospholipid content was higher in CaM (0.503mM) and lower in MM (0.101mM) compared to HM (0.324mM) or CoM (0.265mM). Our optimised method showed good sensitivity, high resolution, and easy sample preparation with minimal loss of target molecules. It is suitable for determining the accurate composition of a large number of bioactive phospholipids with putative health benefits, including plasmalogens, and should aid in selecting appropriate ingredient sources for infant milk substitutes or fortifiers, and for functional foods dedicated to adults.
    Mots-clés : Animals, Camels, crmbm, Humans, Magnetic Resonance Spectroscopy, Milk, Milk, Human, Phospholipids.

  • Laigle, C, Confort-Gouny, S, Le Fur, Y, Cozzone, PJ & Viola, A 2012, “Deletion of TRAAK potassium channel affects brain metabolism and protects against ischemia”, PloS one, vol. 7, no. 12, p. e53266.
    Résumé : Cerebral stroke is a worldwide leading cause of disability. The two-pore domain K⁺ channels identified as background channels are involved in many functions in brain under physiological and pathological conditions. We addressed the hypothesis that TRAAK, a mechano-gated and lipid-sensitive two-pore domain K⁺ channel, is involved in the pathophysiology of brain ischemia. We studied the effects of TRAAK deletion on brain morphology and metabolism under physiological conditions, and during temporary focal cerebral ischemia in Traak⁻/⁻ mice using a combination of in vivo magnetic resonance imaging (MRI) techniques and multinuclear magnetic resonance spectroscopy (MRS) methods. We provide the first in vivo evidence establishing a link between TRAAK and neurometabolism. Under physiological conditions, Traak⁻/⁻ mice showed a particular metabolic phenotype characterized by higher levels of taurine and myo-inositol than Traak⁺/⁺ mice. Upon ischemia, Traak⁻/⁻ mice had a smaller infarcted volume, with lower contribution of cellular edema than Traak⁺/⁺ mice. Moreover, brain microcirculation was less damaged, and brain metabolism and pH were preserved. Our results show that expression of TRAAK strongly influences tissue levels of organic osmolytes. Traak⁻/⁻ mice resilience to cellular edema under ischemia appears related to their physiologically high levels of myo-inositol and of taurine, an aminoacid involved in the modulation of mitochondrial activity and cell death. The beneficial effects of TRAAK deletion designate this channel as a promising pharmacological target for the treatment against stroke.
    Mots-clés : Animals, Brain, crmbm, Cytoprotection, Energy Metabolism, Female, Gene Deletion, Hypoxia-Ischemia, Brain, Infarction, Middle Cerebral Artery, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Potassium Channels.

  • Wybrecht, D, Reuter, F, Zaaraoui, W, Faivre, A, Crespy, L, Rico, A, Malikova, I, Confort-Gouny, S, Soulier, E, Cozzone, PJ, Pelletier, J, Ranjeva, J-P & Audoin, B 2012, “Voxelwise analysis of conventional magnetic resonance imaging to predict future disability in early relapsing-remitting multiple sclerosis”, Multiple sclerosis (Houndmills, Basingstoke, England), vol. 18, no. 11, p. 1585-1591.
    Résumé : BACKGROUND: The ability of conventional magnetic resonance imaging (MRI) to predict subsequent physical disability and cognitive deterioration after a clinically isolated syndrome (CIS) is weak. OBJECTIVES: We aimed to investigate whether conventional MRI changes over 1 year could predict cognitive and physical disability 5 years later in CIS. We performed analyses using a global approach (T(2) lesion load, number of T(2) lesions), but also a topographic approach. METHODS: This study included 38 patients with a CIS. At inclusion, 10 out of 38 patients fulfilled the 2010 revised McDonald's criteria for the diagnosis of multiple sclerosis. Expanded Disability Status Scale (EDSS) evaluation was performed at baseline, year 1 and year 5, and cognitive evaluation at baseline and year 5. T(2)-weighted MRI was performed at baseline and year 1. We used voxelwise analysis to analyse the predictive value of lesions location for subsequent disability. RESULTS: Using the global approach, no correlation was found between MRI and clinical data. The occurrence or growth of new lesions in the brainstem was correlated with EDSS changes over the 5 years of follow-up. The occurrence or growth of new lesions in cerebellum, thalami, corpus callosum and frontal lobes over 1 year was correlated with cognitive impairment at 5 years. CONCLUSION: The assessment of lesion location at the first stage of multiple sclerosis may be of value to predict future clinical disability.
    Mots-clés : crmbm.

  • Zaaraoui, W, Konstandin, S, Audoin, B, Nagel, AM, Rico, A, Malikova, I, Soulier, E, Viout, P, Confort-Gouny, S, Cozzone, PJ, Pelletier, J, Schad, LR & Ranjeva, J-P 2012, “Distribution of brain sodium accumulation correlates with disability in multiple sclerosis: a cross-sectional 23Na MR imaging study”, Radiology, vol. 264, no. 3, p. 859-867.
    Résumé : PURPOSE: To quantify brain sodium accumulations and characterize for the first time the spatial location of sodium abnormalities at different stages of relapsing-remitting (RR) multiple sclerosis (MS) by using sodium 23 ((23)Na) magnetic resonance (MR) imaging. MATERIALS AND METHODS: This study was approved by the local committee on ethics, and written informed consent was obtained from all participants. Three-dimensional (23)Na MR imaging data were obtained with a 3.0-T unit in two groups of patients with RR MS-14 with early RR MS (disease duration <5 years) and 12 with advanced RR MS (disease duration >5 years)-and 15 control subjects. Quantitative assessment of total sodium concentration (TSC) levels within compartments (MS lesions, white matter [WM], and gray matter [GM]) as well as statistical mapping analyses of TSC abnormalities were performed. RESULTS: TSC was increased inside demyelinating lesions in both groups of patients, whereas increased TSC was observed in normal-appearing WM and GM only in those with advanced RR MS. In patients, increased TSC inside GM was correlated with disability (as determined with the Expanded Disability Status Scale [EDSS] score; P = .046, corrected) and lesion load at T2-weighted imaging (P = .003, corrected) but not with disease duration (P = .089, corrected). Statistical mapping analysis showed confined TSC increases inside the brainstem, cerebellum, and temporal poles in early RR MS and widespread TSC increases that affected the entire brain in advanced RR MS. EDSS score correlated with TSC increases inside motor networks. CONCLUSION: TSC accumulation dramatically increases in the advanced stage of RR MS, especially in the normal-appearing brain tissues, concomitant with disability. Brain sodium MR imaging may help monitor the occurrence of tissue injury and disability.
    Mots-clés : Adult, Area Under Curve, Brain, crmbm, Disability Evaluation, Female, Humans, Image Enhancement, Image Interpretation, Computer-Assisted, Magnetic Resonance Imaging, Male, Middle Aged, Multiple Sclerosis, Relapsing-Remitting, Regression Analysis, Sodium, Statistics, Nonparametric.


Journal Article

  • Bettus, G, Ranjeva, J-P, Wendling, F, Bénar, CG, Confort-Gouny, S, Régis, J, Chauvel, P, Cozzone, PJ, Lemieux, L, Bartolomei, F & Guye, M 2011, “Interictal functional connectivity of human epileptic networks assessed by intracerebral EEG and BOLD signal fluctuations”, PloS one, vol. 6, no. 5, p. e20071.
    Résumé : In this study, we aimed to demonstrate whether spontaneous fluctuations in the blood oxygen level dependent (BOLD) signal derived from resting state functional magnetic resonance imaging (fMRI) reflect spontaneous neuronal activity in pathological brain regions as well as in regions spared by epileptiform discharges. This is a crucial issue as coherent fluctuations of fMRI signals between remote brain areas are now widely used to define functional connectivity in physiology and in pathophysiology. We quantified functional connectivity using non-linear measures of cross-correlation between signals obtained from intracerebral EEG (iEEG) and resting-state functional MRI (fMRI) in 5 patients suffering from intractable temporal lobe epilepsy (TLE). Functional connectivity was quantified with both modalities in areas exhibiting different electrophysiological states (epileptic and non affected regions) during the interictal period. Functional connectivity as measured from the iEEG signal was higher in regions affected by electrical epileptiform abnormalities relative to non-affected areas, whereas an opposite pattern was found for functional connectivity measured from the BOLD signal. Significant negative correlations were found between the functional connectivities of iEEG and BOLD signal when considering all pairs of signals (theta, alpha, beta and broadband) and when considering pairs of signals in regions spared by epileptiform discharges (in broadband signal). This suggests differential effects of epileptic phenomena on electrophysiological and hemodynamic signals and/or an alteration of the neurovascular coupling secondary to pathological plasticity in TLE even in regions spared by epileptiform discharges. In addition, indices of directionality calculated from both modalities were consistent showing that the epileptogenic regions exert a significant influence onto the non epileptic areas during the interictal period. This study shows that functional connectivity measured by iEEG and BOLD signals give complementary but sometimes inconsistent information in TLE.
    Mots-clés : crmbm, Electroencephalography, Epilepsy, Humans, Magnetic Resonance Imaging.

  • Crespy, L, Zaaraoui, W, Lemaire, M, Rico, A, Faivre, A, Reuter, F, Malikova, I, Confort-Gouny, S, Cozzone, PJ, Pelletier, J, Ranjeva, J-P & Audoin, B 2011, “Prevalence of grey matter pathology in early multiple sclerosis assessed by magnetization transfer ratio imaging”, PloS one, vol. 6, no. 9, p. e24969.
    Résumé : The aim of the study was to assess the prevalence, the distribution and the impact on disability of grey matter (GM) pathology in early multiple sclerosis. Eighty-eight patients with a clinically isolated syndrome with a high risk developing multiple sclerosis were included in the study. Forty-four healthy controls constituted the normative population. An optimized statistical mapping analysis was performed to compare each subject's GM Magnetization Transfer Ratio (MTR) imaging maps with those of the whole group of controls. The statistical threshold of significant GM MTR decrease was determined as the maximum p value (p<0.05 FDR) for which no significant cluster survived when comparing each control to the whole control population. Using this threshold, 51% of patients showed GM abnormalities compared to controls. Locally, 37% of patients presented abnormalities inside the limbic cortex, 34% in the temporal cortex, 32% in the deep grey matter, 30% in the cerebellum, 30% in the frontal cortex, 26% in the occipital cortex and 19% in the parietal cortex. Stepwise regression analysis evidenced significant association (p = 0.002) between EDSS and both GM pathology (p = 0.028) and T2 white matter lesions load (p = 0.019). In the present study, we evidenced that individual analysis of GM MTR map allowed demonstrating that GM pathology is highly heterogeneous across patients at the early stage of MS and partly underlies irreversible disability.
    Mots-clés : Adolescent, Adult, Brain, Brain Mapping, Case-Control Studies, crmbm, Diagnostic Imaging, Disease Progression, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Middle Aged, Multiple sclerosis, Young Adult.

  • Gour, N, Ranjeva, J-P, Ceccaldi, M, Confort-Gouny, S, Barbeau, E, Soulier, E, Guye, M, Didic, M & Felician, O 2011, “Basal functional connectivity within the anterior temporal network is associated with performance on declarative memory tasks”, NeuroImage, vol. 58, no. 2, p. 687-697.
    Résumé : Spontaneous fluctuations in the blood oxygenation level-dependent (BOLD) signal, as measured by functional magnetic resonance imaging (fMRI) at rest, exhibit a temporally coherent activity thought to reflect functionally relevant networks. Antero-mesial temporal structures are the site of early pathological changes in Alzheimer's disease and have been shown to be critical for declarative memory. Our study aimed at exploring the functional impact of basal connectivity of an anterior temporal network (ATN) on declarative memory. A heterogeneous group of subjects with varying performance on tasks assessing memory was therefore selected, including healthy subjects and patients with isolated memory complaint, amnestic Mild Cognitive Impairment (aMCI) and mild Alzheimer's disease (AD). Using Independent Component Analysis on resting-state fMRI, we extracted a relevant anterior temporal network (ATN) composed of the perirhinal and entorhinal cortex, the hippocampal head, the amygdala and the lateral temporal cortex extending to the temporal pole. A default mode network and an executive-control network were also selected to serve as control networks. We first compared basal functional connectivity of the ATN between patients and control subjects. Relative to controls, patients exhibited significantly increased functional connectivity in the ATN during rest. Specifically, voxel-based analysis revealed an increase within the inferior and superior temporal gyrus and the uncus. In the patient group, positive correlations between averaged connectivity values of ATN and performance on anterograde and retrograde object-based memory tasks were observed, while no correlation was found with other evaluated cognitive measures. These correlations were specific to the ATN, as no correlation between performance on memory tasks and the other selected networks was found. Taken together, these findings provide evidence that basal connectivity inside the ATN network has a functional role in object-related, context-free memory. They also suggest that increased connectivity at rest within the ATN could reflect compensatory mechanisms that occur in response to early pathological insult.
    Mots-clés : Aged, Alzheimer Disease, crmbm, Data Interpretation, Statistical, Educational Status, Executive Function, Female, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Memory, Memory Disorders, Mild cognitive impairment, Nerve Net, Neural Pathways, Neuropsychological Tests, Principal Component Analysis, Psychomotor Performance, Temporal Lobe, Visual Perception.

  • Guedj, E, Bettus, G, Barbeau, EJ, Liégeois-Chauvel, C, Confort-Gouny, S, Bartolomei, F, Chauvel, P, Cozzone, PJ, Ranjeva, J-P & Guye, M 2011, “Hyperactivation of parahippocampal region and fusiform gyrus associated with successful encoding in medial temporal lobe epilepsy”, Epilepsia, vol. 52, no. 6, p. 1100-1109.
    Résumé : PURPOSE: Performance in recognition memory differs among patients with medial temporal lobe epilepsy (MTLE). We aimed to determine if distinct recognition performances (normal vs. impaired) could be related to distinct patterns of brain activation during encoding. METHODS: Event-related functional magnetic resonance imaging (fMRI) activation profiles were obtained during successful encoding of non-material-specific items, in 14 MTLE patients tested for recognition of stimuli afterward. Findings were compared to those of 25 healthy subjects, and voxel-based correlations were assessed between brain activation and performance. KEY FINDINGS: Patients with left and right MTLE showed similar activations and similar performances. As a whole, the group of patients demonstrated altered recognition scores, but three of the seven patients with left MTLE and three of the seven patients with right MTLE exhibited normal performance relative to controls. In comparison to healthy subjects and patients with impaired recognition, patients with normal recognition showed weaker activations in left opercular cortex, but stronger activations in bilateral parahippocampal region/fusiform gyrus (PH/FG). By contrast, patients with impaired performance showed weaker activations in bilateral PH/FG, but stronger activations in a frontal/cingulate and parietal network. Recognition performance was correlated positively to bilateral PH/FG activations, and negatively correlated to bilateral frontal/cingulate activations, in the whole group of patients, as well as in subgroups of patients with either left or right MTLE. SIGNIFICANCE: These results suggest occurrence of effective functional compensation within bilateral PH/FG in MTLE, allowing patients to maintain recognition capability. In contrast, impairment of this perceptive-memory system may lead to alternative activation of an inefficient nonspecific attentional network in patients with altered performance.
    Mots-clés : Adolescent, Adult, crmbm, Epilepsy, Temporal Lobe, Female, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Parahippocampal Gyrus, Prospective Studies, Psychomotor Performance, Recognition (Psychology), Young Adult.

  • Reuter, F, Zaaraoui, W, Crespy, L, Faivre, A, Rico, A, Malikova, I, Confort-Gouny, S, Cozzone, PJ, Ranjeva, J-P, Pelletier, J & Audoin, B 2011, “Cognitive impairment at the onset of multiple sclerosis: relationship to lesion location”, Multiple sclerosis (Houndmills, Basingstoke, England), vol. 17, no. 6, p. 755-758.
    Résumé : The impact of lesion location on cognitive functioning was assessed in a group of 97 patients with a clinically isolated syndrome. Using the Brief Repeatable Battery, we evidenced that 24% of patients showed at least one abnormal test, 20% at least two and 15% at least three. Verbal learning performances were inversely associated with presence of lesions in Broca's area, in the right frontal lobe and in the splenium while spatial learning performances were inversely correlated to the presence of lesions in the deep white matter. No associations were evidenced between lesion location and performance of tasks exploring attention and executive functions.
    Mots-clés : Adult, Attention, Brain, Case-Control Studies, Cognition, Cognition Disorders, crmbm, Demyelinating Diseases, Disability Evaluation, Executive Function, Female, France, Humans, Magnetic Resonance Imaging, Male, Memory, Multiple sclerosis, Neuropsychological Tests, Prevalence, Spinal cord, Verbal Learning, Young Adult.

  • Rico, A, Zaaraoui, W, Franques, J, Attarian, S, Reuter, F, Malikova, I, Confort-Gouny, S, Soulier, E, Pouget, J, Cozzone, PJ, Pelletier, J, Ranjeva, J-P & Audoin, B 2011, “Motor cortical reorganization is present after a single attack of multiple sclerosis devoid of cortico-spinal dysfunction”, Magma (New York, N.Y.), vol. 24, no. 2, p. 77-84.
    Résumé : OBJECT: While occurrence of motor cortical reorganization has been clearly demonstrated in patients with multiple sclerosis (MS), it is not yet clear whether this cortical reorganization constitutes a response to cortico-spinal lesions or to more diffuse damage affecting the neuronal network involved in motor act preparation, or both. We proposed to investigate the changes in the activation pattern during a simple motor task devoid of cortico-spinal dysfunction occurring in patients with clinically isolated syndrome (CIS) suggestive of MS. MATERIALS AND METHODS: Among 15 right-handed CIS patients, we selected eight patients with a preserved central motor pathway established by motor evoked potentials. Ten healthy right-handed gender- and age-matched volunteers were also included. After morphological MRI, subjects performed calibrated conjugated finger flexion and extension movements during fMRI acquisition. RESULTS: In CIS patients, simple movements of the non-dominant hand induced recruitment of the anterior cingulate cortex (BA32) usually involved in complex motor movements. This reorganization was correlated with the diffuse brain tissue damage (brain T₂ lesion load). CONCLUSION: These results suggest that at least part of the cortical reorganization observed during very simple tasks in the earliest stage of MS occurs whether or not the efferent pathways are intact.
    Mots-clés : Adult, Brain Mapping, crmbm, Demyelinating Diseases, Evoked Potentials, Motor, Female, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Motor Activity, Motor Cortex, Multiple sclerosis, Pyramidal Tracts, Young Adult.

  • Viola, A, Confort-Gouny, S, Schneider, JF, Le Fur, Y, Viout, P, Chapon, F, Pineau, S, Cozzone, PJ & Girard, N 2011, “Is brain maturation comparable in fetuses and premature neonates at term equivalent age?”, AJNR. American journal of neuroradiology, vol. 32, no. 8, p. 1451-1458.
    Résumé : BACKGROUND AND PURPOSE: Improved knowledge of brain maturation in fetuses and premature neonates is crucial for the early detection of pathologies and would help determine whether MR data from the premature brain might be used to evaluate fetal maturation. Using diffusion-weighted MR imaging and (1)H-MR spectroscopy, we compared cerebral microstructure and metabolism in normal in utero fetuses imaged near term and premature neonates imaged at term equivalent. MATERIALS AND METHODS: Forty-eight subjects were investigated: 24 in utero fetuses (mean gestational age, 37 ± 1 weeks) and 24 premature neonates (mean postconceptional age, 37 ± 1 weeks). ADC values were measured in cerebellum, pons, white matter, brain stem, basal ganglia, and thalamus. MR spectroscopy was performed in deep white matter. RESULTS: Mean ADC values from fetuses and premature neonates were comparable except for the pons and the parietal white matter. ADC values were lower in the pons of premature neonates, whereas greater values were found in their parietal white matter compared with fetuses. Proton MR spectroscopy showed higher levels of NAA/H(2)O, Glx/H(2)O, tCr/H(2)O, and mIns/H(2)O in premature neonates compared with fetuses. CONCLUSIONS: Our study provides evidence of subtle anomalies in the parietal white matter of healthy premature neonates. In addition, the reduced ADC values in the pons together with the increased levels of NAA/H(2)O, tCr/H(2)O, and Glx/H(2)O in the centrum semiovale suggest a more advanced maturation in some white matter regions. Our results indicate that MR data from the premature brain are not appropriate for the assessment of the fetal brain maturation.
    Mots-clés : Brain, crmbm, Fetal Organ Maturity, Fetus, Gestational Age, Humans, Infant, Newborn, Infant, Premature, Term Birth.

  • Zaaraoui, W, Crespy, L, Rico, A, Faivre, A, Soulier, E, Confort-Gouny, S, Cozzone, PJ, Pelletier, J, Ranjeva, J-P, Kaphan, E & Audoin, B 2011, “In vivo quantification of brain injury in adult Niemann-Pick Disease Type C”, Molecular genetics and metabolism, vol. 103, no. 2, p. 138-141.
    Résumé : Development of surrogate markers is necessary to assess the potential efficacy of new therapeutics in Niemann-Pick Disease Type C (NP-C). In the present study, magnetization transfer ratio (MTR) imaging, a quantitative MRI imaging technique sensitive to subtle brain microstructural changes, was applied in two patients suffering from adult NP-C. Statistical mapping analysis was performed to compare each patient's MTR maps with those of a group of 34 healthy controls to quantify and localize the extent of brain injury of each patient. Using this method, pathological changes were evidenced in the cerebellum, the thalami and the lenticular nuclei in both patients and also in the fronto-temporal cortices in the patient with the worse functional deficit. In addition, white matter changes were located in the midbrain, the cerebellum and the fronto-temporal lobes in the patient with the higher level of disability and in only one limited periventricular white matter region in the other patient. A 6-month follow-up was performed in the patient with the lower functional deficit and evidenced significant extension of grey matter (GM) and white matter (WM) injuries during the following period (14% of increased injury for GM and 53% for WM). This study demonstrates that significant brain injury related to clinical deficit can be assessed in vivo in adult NP-C using MTR imaging. Although preliminary, these findings suggest that MTR imaging may be a relevant candidate for the development of biomarker in NP-C.
    Mots-clés : Adult, Biological Markers, Brain Injuries, Female, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Niemann-Pick Disease, Type C, Young Adult.

  • Zaaraoui, W, Reuter, F, Rico, A, Faivre, A, Crespy, L, Malikova, I, Soulier, E, Viout, P, Le Fur, Y, Confort-Gouny, S, Cozzone, PJ, Pelletier, J, Ranjeva, J-P & Audoin, B 2011, “Occurrence of neuronal dysfunction during the first 5 years of multiple sclerosis is associated with cognitive deterioration”, Journal of neurology, vol. 258, no. 5, p. 811-819.
    Résumé : Brain neuronal injury is present in patients suffering from multiple sclerosis (MS) from the earliest stage of the disease; however, the functional counterpart of early neuronal injury is largely unknown. The goal of this study was to assess the potential impact of early neuronal dysfunction affecting white matter (WM), grey matter (GM), or the cerebellum on cognitive deterioration and/or EDSS progression during the first 5 years of MS. Magnetic resonance spectroscopic (MRS) examinations and neuropsychological assessments were performed in 23 patients included after the first clinical attack of MS and 24 healthy controls. The same protocol was performed in patients after a follow-up of 5 years. Metabolic neuronal function was assessed in WM (splenium of corpus callosum), GM (dorsal posterior cingulate cortex), and the cerebellum by evaluating N-acetylaspartate (NAA) levels. During follow-up, 39% of patients showed cognitive deterioration and 43% showed a deterioration in their EDSS. Patients with cognitive deterioration had greater NAA level reductions during follow-up in the cerebellum (p = 0.003) and WM (p = 0.02) compared to patients without cognitive deterioration. In addition, patients with cognitive deterioration had higher progression of T2 lesion load (T2LL) during the follow-up period compared to patients without cognitive deterioration (p = 0.03). No differences between patients with and without EDSS progression in terms of NAA levels or T2LL were observed. The present longitudinal study found evidence that, during the first 5 years of MS, cognitive deterioration is associated with the progression of neuronal dysfunction and tissue injury as assessed by MRS and T2LL, respectively.
    Mots-clés : Adult, Aspartic Acid, Cognition Disorders, crmbm, Disease Progression, Female, Humans, Magnetic Resonance Spectroscopy, Male, Multiple sclerosis, Neurons, Neuropsychological Tests, Young Adult.

  • Zanin, E, Ranjeva, J-P, Confort-Gouny, S, Guye, M, Denis, D, Cozzone, PJ & Girard, N 2011, “White matter maturation of normal human fetal brain. An in vivo diffusion tensor tractography study”, Brain and behavior, vol. 1, no. 2, p. 95-108.
    Résumé : We demonstrate for the first time the ability to determine in vivo and in utero the transitions between the main stages of white matter (WM) maturation in normal human fetuses using magnetic resonance diffusion tensor imaging (DTI) tractography. Biophysical characteristics of water motion are used as an indirect probe to evaluate progression of the tissue matrix organization in cortico-spinal tracts (CSTs), optic radiations (OR), and corpus callosum (CC) in 17 normal human fetuses explored between 23 and 38 weeks of gestation (GW) and selected strictly on minimal motion artifacts. Nonlinear polynomial (third order) curve fittings of normalized longitudinal and radial water diffusivities (Z-scores) as a function of age identify three different phases of maturation with specific dynamics for each WM bundle type. These phases may correspond to distinct cellular events such as axonal organization, myelination gliosis, and myelination, previously reported by other groups on post-mortem fetuses using immunostaining methods. According to the DTI parameter dynamics, we suggest that myelination (phase 3) appears early in the CSTs, followed by the OR and by the CC, respectively. DTI tractography provides access to a better understanding of fetal WM maturation.
    Mots-clés : crmbm.


Journal Article

  • Audoin, B, Zaaraoui, W, Reuter, F, Rico, A, Malikova, I, Confort-Gouny, S, Cozzone, PJ, Pelletier, J & Ranjeva, J-P 2010, “Atrophy mainly affects the limbic system and the deep grey matter at the first stage of multiple sclerosis”, Journal of neurology, neurosurgery, and psychiatry, vol. 81, no. 6, p. 690-695.
    Résumé : BACKGROUND: The existence of grey matter (GM) atrophy right after the first clinical event suggestive of multiple sclerosis (MS) remains controversial. The aim of this study was therefore to establish whether regional GM atrophy is already present in the earliest stage of MS assessing regional GM atrophy in a large group of patients. METHODS: Sixty-two patients with a clinically isolated syndrome (CIS) were examined on a 1.5 T MR imager within 6 months after their first clinical events. A group of 37 matched healthy control subjects were also included in the study. An optimised voxel-based morphometry (VBM) method customised for MS was applied on volumetric T(1)-weighted images. The functional status of patients was assessed using the Expanded Disability Status Scale (EDSS) and the Brief Repeatable Battery. RESULTS: VBM analysis (p<0.005, familywise error corrected) on patients versus control subjects showed the presence of significant focal GM atrophy in patients involving the bilateral insula, the bilateral orbitofrontal cortices, the bilateral internal and inferior temporal regions, the posterior cingulate cortex, the bilateral thalami, the bilateral caudate nuclei, the bilateral lenticular nuclei and the bilateral cerebellum. EDSS was slightly correlated (rho=-0.37 p=0.0027) with the atrophy of the right cerebellum. No correlations have been evidenced between the cognitive status of patients and the regional GM atrophy. CONCLUSION: The present study performed on a large group of CIS patients demonstrated that regional GM atrophy is present right after the first clinical event of multiple sclerosis and mainly affects the deep GM and the limbic system.
    Mots-clés : Adult, Amygdala, Atrophy, Cerebral Cortex, crmbm, Female, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Multiple sclerosis, Severity of Illness Index, Young Adult.

  • Bettus, G, Bartolomei, F, Confort-Gouny, S, Guedj, E, Chauvel, P, Cozzone, PJ, Ranjeva, J-P & Guye, M 2010, “Role of resting state functional connectivity MRI in presurgical investigation of mesial temporal lobe epilepsy”, Journal of neurology, neurosurgery, and psychiatry, vol. 81, no. 10, p. 1147-1154.
    Résumé : OBJECTIVE: The authors aimed to determine the ability of resting-state functional connectivity MRI (fcMRI) to lateralise/localise the epileptogenic zone in patients presenting with mesial temporal lobe epilepsy (MTLE) at the individual level. METHODS: Basal functional connectivity (BFC) was evaluated in each hemisphere of 22 MTLE patients. 200 volumes were acquired using a single-shot GE-EPI sequence during a resting period of 10 min at 1.5 T. The signal time-course was extracted from 10 regions of interest (ROIs), five ROIs in each hemisphere, usually involved in epileptogenic networks of MTLE. Normalised correlation coefficients between pairs of ROIs signal time-courses were computed to reflect BFC. Based on normative BFC values obtained from 36 controls, the number of BFC decreases and increases were determined in each hemisphere for each patient. RESULTS: BFC decreases were found bilaterally, although the number of decreased links was significantly higher in the epileptogenic side (p=0.025). Conversely, BFC increases were found almost exclusively in the contralateral lobe leading to a strong test effect for locating the non-epileptic lobe with a sensitivity of 64% and a specificity of 91% (p<0.001). The most frequently disconnected areas were the entorhinal cortex and the anterior hippocampus in the epileptic lobe, while contralateral BFC increases involved preferentially hippocampus and amygdala. CONCLUSIONS: This study demonstrates that the presence of BFC increases in the non-epileptic side was paradoxically the most specific marker of epileptogenic zone localisation, and suggests that a single resting-state fcMRI could be useful in the presurgical assessment of MTLE at an individual level.
    Mots-clés : Adult, crmbm, Epilepsy, Temporal Lobe, Female, Functional Laterality, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Models, Anatomic, Neural Pathways, Neuropsychological Tests, Sensitivity and Specificity, Temporal Lobe.

  • Didic, M, Ranjeva, J-P, Barbeau, E, Confort-Gouny, S, Fur, YL, Felician, O, Mancini, J, Poncet, M, Ceccaldi, M & Cozzone, P 2010, “Impaired visual recognition memory in amnestic mild cognitive impairment is associated with mesiotemporal metabolic changes on magnetic resonance spectroscopic imaging”, Journal of Alzheimer's disease: JAD, vol. 22, no. 4, p. 1269-1279.
    Résumé : In the early stages of Alzheimer's disease (AD), neurofibrillary tangles develop in the mesial temporal lobe (MTL), first in the anterior subhippocampal (perirhinal/entorhinal) cortex and then in the hippocampal formation. This region plays a key role in visualrecognition memory (VRM). VRM has been reported to be impaired in patients with amnestic mild cognitive impairment (aMCI). The aim of the present study was to determine if an impairment of VRM is associated with metabolic changes in the MTL using magnetic resonance spectroscopic imaging and if evaluating VRM can contribute to the early diagnosis of AD. 28 patients with aMCI and 28 controls underwent a full neuropsychological assessment including an evaluation of VRM using the DMS48. NAA/mIno ratios, reduced in patients with AD and associated with the severity of pathological changes, were determined in the MTL. aMCI-patients were further divided into two subgroups according to their VRM performance. aMCI-patients showed decreased NAA/mIno levels in the right hippocampus compared with controls. aMCI-patients with impaired VRM showed decreased NAA/mIno ratios in the MTL bilaterally, including a region that sampled the left anterior subhippocampal cortex, compared to controls. No changes were found in aMCI patients with normal VRM. Performance on the DMS48 correlated with NAA/mIno levels in the anterior MTL. Clinical 6-year follow-up data (available for 78.6% of the aMCI-patients) indicates that impaired performance on the DMS48 could predict conversion to AD with a sensitivity and specificity of 81.8%. These findings provide further evidence that impaired VRM, as a hallmark of MTL dysfunction, may contribute to the early diagnosis of AD.
    Mots-clés : Aged, Aged, 80 and over, Amnesia, Analysis of Variance, Brain Mapping, Cognition Disorders, crmbm, Female, hippocampus, Humans, Magnetic Resonance Spectroscopy, Male, Middle Aged, Neuropsychological Tests, Recognition (Psychology), Statistics, Nonparametric, Temporal Lobe.

  • Guedj, E, Barbeau, EJ, Liégeois-Chauvel, C, Confort-Gouny, S, Bartolomei, F, Chauvel, P, Cozzone, PJ, Ranjeva, JP, Mundler, O & Guye, M 2010, “Performance in recognition memory is correlated with entorhinal/perirhinal interictal metabolism in temporal lobe epilepsy”, Epilepsy & behavior: E&B, vol. 19, no. 4, p. 612-617.
    Résumé : In addition to the hippocampus, the entorhinal/perirhinal cortices are often involved in temporal lobe epilepsy (TLE). It has been proposed that these anterior parahippocampal structures play a key role in recognition memory. We studied the voxel-based PET correlation between number of correctly recognized targets in a new recognition memory paradigm and interictal cerebral metabolic rate for glucose, in 15 patients with TLE with hippocampal sclerosis. In comparison to healthy subjects, patients had decreased recognition of targets (P<0.001) and ipsilateral hypometabolism (relative to side of hippocampal sclerosis) of the hippocampus, entorhinal/perirhinal cortices, medial temporal pole, and middle temporal gyrus (P<0.05, corrected by false discovery rate method). Performance correlated with interictal metabolism of ipsilateral entorhinal/perirhinal cortices (P<0.005, Spearman's rank test), but this relationship was not significant in the hippocampus itself (P>0.18, Spearman's rank test). These findings highlight the preferential involvement of entorhinal/perirhinal cortices in recognition memory in patients with TLE, and suggest that recognition memory paradigms may be useful in assessing anterior parahippocampal functional status in TLE.
    Mots-clés : Adult, crmbm, Entorhinal Cortex, Epilepsy, Temporal Lobe, Female, Fluorodeoxyglucose F18, hippocampus, Humans, Male, Memory Disorders, Neuropsychological Tests, Positron-Emission Tomography, Recognition (Psychology), Statistics as Topic, Statistics, Nonparametric, Young Adult.

  • Jure, L, Zaaraoui, W, Rousseau, C, Reuter, F, Rico, A, Malikova, I, Confort-Gouny, S, Cozzone, PJ, Pelletier, J, Ranjeva, J-P & Audoin, B 2010, “Individual voxel-based analysis of brain magnetization transfer maps shows great variability of gray matter injury in the first stage of multiple sclerosis”, Journal of magnetic resonance imaging: JMRI, vol. 32, no. 2, p. 424-428.
    Résumé : In multiple sclerosis (MS), it seems likely that the variability of the long-term disability might be partly due to the variability of the early gray matter (GM) injury. In the present study, we assessed the variability of GM injury in early MS, using a method designed to determine individual pathological GM patterns. Eighteen patients presenting with a clinically isolated syndrome and 24 healthy matched control subjects were included in this study. Patients were explored using a 1.5 Tesla MR scanner (Magnetom Vision Plus; Siemens). Brain MR protocol included magnetization transfer ratio imaging (MTR). Statistical mapping analyses were performed to compare each subject's GM MTR maps with those of the whole group of control subjects (SPM5). The statistical threshold was taken to be the maximum P value showing no significant cluster when any control individual was compared with the whole control population. GM abnormalities were observed in 83% of the patients, ranging in size from 0.3 to 125 cm(3). Among the patients with GM abnormalities, 87% had abnormalities located in the temporal cortex, 80% in the frontal cortex, 80% in the limbic cortex, 73% in the posterior fossa, 53% in the deep GM, 47% in the parietal cortex, and 47% in the occipital cortex. Individual statistical mapping of MTR data, which gives a quantitative assessment of individual GM lesions, demonstrates great variability of grey matter injury in the first stage of multiple sclerosis.
    Mots-clés : Adolescent, Adult, Brain, Brain Mapping, Case-Control Studies, crmbm, Diagnostic Imaging, Disease Progression, Female, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Middle Aged, Multiple sclerosis, Reproducibility of Results.

  • Le Fur, Y, Nicoli, F, Guye, M, Confort-Gouny, S, Cozzone, PJ & Kober, F 2010, “Grid-free interactive and automated data processing for MR chemical shift imaging data”, Magnetic Resonance Materials in Physics, Biology and Medicine, vol. 23, no. 1, p. 23-30.
    Résumé : PURPOSE: Today's available chemical shift imaging (CSI) analysis tools are based on Fourier transform of the entire data set prior to interactive display. This strategy is associated with limitations particularly when arbitrary voxel positions within a 3D spatial volume are needed by the user. In this work, we propose and demonstrate a processing-resource-efficient alternative strategy for both interactive and automated CSI data processing up to three spatial dimensions. METHODS: This approach uses real-time voxel-shift by first-order phase manipulation as a basis and therefore allows grid-free voxel positioning within the 3D volume. The corresponding spectrum is extracted from the 4D data (3D spatial/1D spectral) at each time a voxel position is selected. The spatial response function and hence the exact voxel size and shape are calculated in parallel including the same processing parameters. Using this mechanism sequentially along with AMARES time-domain modeling, we also implemented automated quantitative and B (0)-insensitive metabolite mapping. RESULTS: Metabolite maps of N-acetyl aspartate, choline and creatine were generated using (1)H-CSI data from the brain of healthy volunteers and patients with tumor and epilepsy. (31)P-3D-CSI of the heart of a healthy volunteer is also shown. CONCLUSION: The calculated metabolite maps demonstrate good stability and accuracy of the algorithm in all situations tested. The suggested algorithm constitutes therefore an attractive alternative to existing CSI processing strategies.
    Mots-clés : Aspartic Acid, Automatic Data Processing, Brain, Brain Mapping, Brain Neoplasms, Case-Control Studies, Choline, Creatine, crmbm, Epilepsy, Fourier Analysis, Humans, Imaging, Three-Dimensional, Magnetic Resonance Imaging, Reproducibility of Results, Sensitivity and Specificity.

  • Zaaraoui, W, Rico, A, Audoin, B, Reuter, F, Malikova, I, Soulier, E, Viout, P, Le Fur, Y, Confort-Gouny, S, Cozzone, PJ, Pelletier, J & Ranjeva, J-P 2010, “Unfolding the long-term pathophysiological processes following an acute inflammatory demyelinating lesion of multiple sclerosis”, Magnetic resonance imaging, vol. 28, no. 4, p. 477-486.
    Résumé : BACKGROUND: Acute symptomatic inflammation is a main feature of multiple sclerosis but pathophysiological processes underlying total or partial recovery are poorly understood. OBJECTIVE: To characterize in vivo these processes at molecular, structural and functional levels using multimodal MR methods. METHODS: A neuroimaging 3-year follow-up (Weeks 0, 3, 11, 29, 59 and 169) was conducted on a 41-year-old woman presenting at baseline with a large acute demyelinating lesion of multiple sclerosis. Conventional magnetic resonance imaging (MRI), magnetization transfer imaging, diffusion-weighted imaging, functional MRI and magnetic resonance spectroscopy were conducted at 1.5 T. RESULTS: Patient presenting with subacute left hemiplegia recovered progressively (expended disability status scale 7 to 5.5). The MR exploration demonstrated structural functional and metabolic impairments at baseline. Despite restoration of the blood brain barrier integrity, high lactate levels persisted for several weeks concomitant with glial activation. Slow and progressive structural and metabolic restorations occurred from baseline to W169 (lesion volume -64%; apparent diffusion coefficient -14.7%, magnetization transfer ratio +14%, choline -51%, lipids -78%, N-acetylaspartate +77%) while functionality of the motor system recovered. CONCLUSIONS: Multimodal MRI/MRS evidenced long-term dynamics recovery processes involving tissue repair, glial activation, recovery of neuronal function and functional systems. This may impact on customized rehabilitation strategies generally focused on the first months following the onset of symptoms.
    Mots-clés : Acute Disease, Adult, Brain, Female, Humans, Inflammation, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Multiple sclerosis.


Journal Article

  • Bettus, G, Guedj, E, Joyeux, F, Confort-Gouny, S, Soulier, E, Laguitton, V, Cozzone, PJ, Chauvel, P, Ranjeva, J-P, Bartolomei, F & Guye, M 2009, “Decreased basal fMRI functional connectivity in epileptogenic networks and contralateral compensatory mechanisms”, Human brain mapping, vol. 30, no. 5, p. 1580-1591.
    Résumé : A better understanding of interstructure relationship sustaining drug-resistant epileptogenic networks is crucial for surgical perspective and to better understand the consequences of epileptic processes on cognitive functions. We used resting-state fMRI to study basal functional connectivity within temporal lobes in medial temporal lobe epilepsy (MTLE) during interictal period. Two hundred consecutive single-shot GE-EPI acquisitions were acquired in 37 right-handed subjects (26 controls, eight patients presenting with left and three patients with right MTLE). For each hemisphere, normalized correlation coefficients were computed between pairs of time-course signals extracted from five regions involved in MTLE epileptogenic networks (Brodmann area 38, amygdala, entorhinal cortex (EC), anterior hippocampus (AntHip), and posterior hippocampus (PostHip)). In controls, an asymmetry was present with a global higher connectivity in the left temporal lobe. Relative to controls, the left MTLE group showed disruption of the left EC-AntHip link, and a trend of decreased connectivity of the left AntHip-PostHip link. In contrast, a trend of increased connectivity of the right AntHip-PostHip link was observed and was positively correlated to memory performance. At the individual level, seven out of the eight left MTLE patients showed decreased or disrupted functional connectivity. In this group, four patients with left TLE showed increased basal functional connectivity restricted to the right temporal lobe spared by seizures onset. A reverse pattern was observed at the individual level for patients with right TLE. This is the first demonstration of decreased basal functional connectivity within epileptogenic networks with concomitant contralateral increased connectivity possibly reflecting compensatory mechanisms.
    Mots-clés : Adult, Beta Rhythm, crmbm, Epilepsy, Temporal Lobe, Female, Functional Laterality, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Middle Aged, Models, Neurological, Neural Pathways, Oxygen, Rest, Statistics as Topic, Temporal Lobe, Young Adult.

  • Reuter, F, Del Cul, A, Malikova, I, Naccache, L, Confort-Gouny, S, Cohen, L, Cherif, AA, Cozzone, PJ, Pelletier, J, Ranjeva, J-P, Dehaene, S & Audoin, B 2009, “White matter damage impairs access to consciousness in multiple sclerosis”, NeuroImage, vol. 44, no. 2, p. 590-599.
    Résumé : Global neuronal workspace theory predicts that damage to long-distance white matter (WM) tracts should impair access to consciousness during the perception of brief stimuli. To address this issue, we studied visual backward masking in 18 patients at the very first clinical stage of multiple sclerosis (MS), a neurological disease characterized by extensive WM damage, and in 18 matched healthy subjects. In our masking paradigm, the visibility of a digit stimulus increases non-linearly as a function of the interval duration between this target and a subsequent mask. In order to characterize quantitatively, for each subject, the transition between non-conscious and conscious perception of the stimulus, we used non-linear regression to fit a sigmoid curve to objective performance and subjective visibility reports as a function of target-mask delay. The delay corresponding to the inflexion point of the sigmoid, where visibility suddenly increases, was termed the "non-linear transition threshold" and used as a summary measure of masking efficiency. Objective and subjective non-linear transition thresholds were highly correlated across subjects in both groups, and were higher in patients compared to controls. In patients, variations in the non-linear transition threshold were inversely correlated to the Magnetization transfer ratio (MTR) values inside the right dorsolateral prefrontal WM, the right occipito-frontal fasciculus and the left cerebellum. This study provides clinical evidence of a relationship between impairments of conscious access and integrity of large WM bundles, particularly involving prefrontal cortex, as predicted by global neuronal workspace theory.
    Mots-clés : Adolescent, Adult, Cognition, Cognition Disorders, Consciousness, crmbm, Demyelinating Diseases, Female, Humans, Male, Middle Aged, Multiple sclerosis, Nerve Fibers, Myelinated, Perceptual Masking, Visual Perception, Young Adult.


Journal Article

  • Audoin, B, Reuter, F, Duong, MVA, Malikova, I, Confort-Gouny, S, Cherif, AA, Cozzone, PJ, Pelletier, J & Ranjeva, JP 2008, “Efficiency of cognitive control recruitment in the very early stage of multiple sclerosis: a one-year fMRI follow-up study”, Multiple sclerosis (Houndmills, Basingstoke, England), vol. 14, no. 6, p. 786-792.
    Résumé : Functional magnetic resonance imaging (FMRI) studies have established that patients with multiple sclerosis show stronger activation in the lateral prefrontal cortices (LPFC) than healthy control subjects during effortful cognitive tasks. The aim of the present study was to assess the impact of these activation changes on cognitive performances. In addition to 19 controls, who were tested at a single time-point to define a standard pattern of fMRI activation during the performance of the Paced Auditory Serial Addition Task (PASAT), 13 patients with clinically isolated syndrome underwent a longitudinal fMRI examination while performing the PASAT at the beginning of the study (M0) and one year later (M12). Relative to the M0 scores, PASAT performances improved in eight patients (group A) and either decreased (n = 4) or remained unchanged (n = 1) (group B) in five patients at M12. Random effect analyses (SPM2; Wellcome Institute, London, England) were performed to compare intra-group time-related effects on brain activation (paired t-test between M0 and M12), and inter-group differences were also compared between the two groups of patients (analysis of covariance with PASAT performances as the covariate). Relative to group B, group A showed larger increase in activation between M0 and M12 in the right LPFC. In the whole group of patients, interaction analyses showed that the differences in the PASAT scores between M0 and M12 were correlated with the differences in activation observed in the right LPFC. This longitudinal study shows that in patients with early multiple sclerosis, the increased levels of activation in the right LPFC was associated with improved individual working memory and processing speed performances.
    Mots-clés : Adaptation, Physiological, Adult, Cognition, crmbm, Early Diagnosis, Female, Follow-Up Studies, Humans, Longitudinal Studies, Magnetic Resonance Imaging, Male, Memory, Short-Term, Multiple sclerosis, Neuropsychological Tests, Prefrontal Cortex.

  • Barbeau, EJ, Ranjeva, JP, Didic, M, Confort-Gouny, S, Felician, O, Soulier, E, Cozzone, PJ, Ceccaldi, M & Poncet, M 2008, “Profile of memory impairment and gray matter loss in amnestic mild cognitive impairment”, Neuropsychologia, vol. 46, no. 4, p. 1009-1019.
    Résumé : The present study assessed the patterns of cortical gray matter (GM) loss in patients with amnestic mild cognitive impairment (aMCI) with distinct profiles of memory impairment, i.e. aMCI patients failing on both recall and recognition memory vs. aMCI patients showing impaired recall but preserved recognition memory. This distinction is usually not taken into account in studies on aMCI and the aim of the present study was to assess whether this distinction is useful. Twenty-eight aMCI patients and 28 matched controls subjects were included. All aMCI patients failed a recall memory task (inclusion criteria). All underwent a visual recognition memory task (DMS48). However, 12 succeeded on this task while 16 failed. Relative gray matter (GM) loss was measured using voxel-based morphometry. When comparing aMCI patients to controls regardless of the profile of memory impairment, GM loss was found in temporal, parietal and frontal areas. However, in aMCI patients with preserved recognition (but impaired recall), GM loss was confined to frontal areas. This contrasted with GM loss in the right medial temporal lobe and bilateral temporo-parietal regions in aMCI patients with impaired recall and recognition memory, a pattern of GM loss usually described in early AD. We conclude that different profiles of memory impairment in aMCI patients are associated with distinct patterns of GM loss.
    Mots-clés : Aged, Brain Mapping, Cognition Disorders, crmbm, Female, Humans, Magnetic Resonance Imaging, Male, Memory Disorders, Middle Aged, Neuroglia, Neuropsychological Tests, Pattern Recognition, Visual.

  • Callot, V, Galanaud, D, Le Fur, Y, Confort-Gouny, S, Ranjeva, J-P & Cozzone, PJ 2008, “(1)H MR spectroscopy of human brain tumours: a practical approach”, European journal of radiology, vol. 67, no. 2, p. 268-274.
    Résumé : Magnetic resonance spectroscopy (MRS) is proposed in addition to magnetic resonance imaging (MRI) to help in the characterization of brain tumours by detecting metabolic alterations that may be indicative of the tumour class. MRS can be routinely performed on clinical magnets, within a reasonable acquisition time and if performed under adequate conditions, MRS is reproducible and thus can be used for longitudinal follow-up of treatment. MRS can also be performed in clinical practice to guide the neurosurgeon into the most aggressive part of the lesions or to avoid unnecessary surgery, which may furthermore decrease the risk of surgical morbidity.
    Mots-clés : Brain Chemistry, Brain Neoplasms, crmbm, Diagnosis, Differential, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Spectroscopy.

  • Combaz, X, Girard, N, Scavarda, D, Chapon, F, Pineau, S, Levrier, O, Viout, P & Confort-Gouny, S 2008, “[Imaging of brain tumors in children]”, Journal of Neuroradiology. Journal De Neuroradiologie, vol. 35, no. 5, p. 261-267.
    Résumé : Few studies exist in the literature on pediatric brain tumors examined with advances MRI techniques. The aim of this review is to try to find out some specific tissular characteristics of the main cerebral tumors encountered in children, especially through diffusion imaging, perfusion imaging and proton magnetic resonance spectroscopy (MRS). However, hemispheric cerebral tumors are not as common as in the adult population.
    Mots-clés : Brain, Brain Neoplasms, Child, Child, Preschool, Contrast Media, crmbm, Humans, Infant, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy.

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