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In Alzheimer’s disease, the tauopathy is known as a major mechanism responsible for the development of cognitive deficits. Early biomarkers of such affectations for diagnosis/stratification are crucial in Alzheimer’s disease research, and brain connectome studies increasingly show their potential establishing pathology fingerprints at the network level. In this context, we conducted an in vivo multimodal MRI study on young Thy-Tau22 transgenic mice expressing tauopathy, performing resting state functional MRI and structural brain imaging to identify early connectome signatures of the pathology, relating with histological and behavioural investigations. In the prodromal phase of tauopathy, before the emergence of cognitive impairments, Thy-Tau22 mice displayed selective modifications of brain functional connectivity involving three main centres: hippocampus (HIP), amygdala (AMG) and the isocortical areas, notably the somatosensory (SS) cortex. Each of these regions showed differential histopathological profiles. Disrupted ventral HIP-AMG functional pathway and altered dynamic functional connectivity were consistent with high pathological tau deposition and astrogliosis in both hippocampus and amygdala, and significant microglial reactivity in amygdalar nuclei. These patterns were concurrent with widespread functional hyperconnectivity of memory-related circuits of dorsal hippocampus—encompassing dorsal HIP-SS communication—in the absence of significant cortical histopathological markers. These findings suggest the coexistence of two intermingled mechanisms of response at the functional connectome level in the early phases of pathology: a maladaptive and a likely compensatory response. Captured in the connectivity patterns, such first responses to pathology could further be used in translational investigations as a lead towards an early biomarker of tauopathy as well as new targets for future treatments.

Background Central nervous system damage in multiple sclerosis (MS) is responsible for serious deficiencies. Current therapies are focused on the treatment of inflammation; however, there is an urgent need for innovative therapies promoting neuroregeneration, particularly myelin repair. It is demonstrated that testosterone can act through neural androgen receptors and several clinical observations stimulated an interest in the potential protective effects of testosterone treatment for MS. Here, we sought to demonstrate the effects of a testosterone supplementation in testosterone-deficient men with relapsing-remitting MS. Methods/design This report presents the rationale and methodology of TOTEM RRMS, a French, phase 2, multicenter, randomized, placebo-controlled, and double-blind trial, which aims to prevent the progression of MS in men with low testosterone levels by administration of testosterone undecanoate, who were kept under natalizumab (Tysabri®) to overcome the anti-inflammatory effect of testosterone. Forty patients will be randomized into two groups receiving either a testosterone treatment (Nebido®) or a matching placebo. The intervention period for each group will last 66 weeks (treatment will be injected at baseline, week 6, and then every 12 weeks). The main objective is to determine the neuroprotective and remyelinating effects of testosterone using tensor diffusion imaging techniques and thalamic atrophy analyses. As secondary objectives, impacts of the testosterone supplementation will be studied using other conventional and unconventional MRI parameters and with clinical outcomes. Discussion The action of testosterone is observed in different experimental autoimmune encephalomyelitis models and epidemiological studies in humans. However, despite several preclinical data and some small clinical trials in MS, clear evidence for a therapeutic effect of hormone therapy is still missing. Therefore, our goal is to demonstrate the effects of testosterone therapies in MS. As there is no effective treatment currently available on fatigue in MS, careful attention should also be paid to secondary endpoints: fatigue, cognitive functions, and other symptoms that may improve life quality. Assuming a positive outcome of the trial, this treatment could be considered as a new neuroprotective and remyelinating therapy in relapsing-remitting MS and could be applicable to other demyelinating diseases. Trial registration ClinicalTrials.gov NCT03910738. Registered on 10 April 2019.

International audience; Nous proposons, dans le cadre de cette courte étude, des éléments d'analyse et des pistes de réflexion sur la pratique de la problématisation en classe de terminale, et ses difficultés. Partant du constat de la centralité des problèmes dans le programme officiel, fixant les finalités de l'enseignement de la philosophie au lycée, nous proposerons d'examiner les obstacles qui rendent cet aspect du travail de l'enseignant… problématique ! Au-delà de la formule et du jeu de mot, il s'agit plus sérieusement d'interroger la possibilité d'enseigner la problématisation elle-même, en partant du postulat que celle-ci désigne la capacité à identifier et à expliciter le caractère problématique d'une notion, d'un sujet ou d'un texte, et non la connaissance factuelle ou thématique des problèmes philosophiques académiques, issus de la tradition. C'est ce qui explique la référence du titre de cet article à la question de Socrate concernant la vertu, mais en la transposant ici à la problématisation : si celle-ci dépend d'un exercice pratique et d'un usage concret, non pas d'une connaissance théorique et abstraite, peut-on vraiment l'enseigner, en supposant qu'on la possède déjà soi-même ? Dans quelle mesure le professeur de philosophie peut-il réellement transmettre le sens du problème à ses élèves ? Peut-on trouver une méthode fiable, simple à acquérir et facilement reproductible, pour poser des problèmes ? Suffit-il de suivre mécaniquement des règles techniques et de les appliquer correctement, comme on applique les instructions d'un protocole ou d'un rituel ? Ou faut-il en passer par un long et patient travail, fait d'exercices répétés, d'essais et d'erreurs rectifiés, permettant de s'incorporer le sens du problème, de savoir poser des problèmes, de problématiser les objets étudiés ? Voilà les questions directrices qui animent et qui orientent notre propos, dont l'enjeu principal est de mettre en évidence les conditions mais aussi d'expliciter les difficultés que peut rencontrer l'enseignant en philosophie quand il s'efforce de faire comprendre aux élèves de classe de terminale, que ce soit en série générale ou en série technologique, en quoi consiste problématiser, sans se limiter au seul cas de la dissertation et de l'analyse d'un sujet d'examen.

PurposeTo propose an efficient retrospective image-based method for motion correction of multi-contrast acquisitions with a low number of available images (MC-MoCo) and evaluate its use in 3D inhomogeneous Magnetization Transfer (ihMT) experiments in the human brain.MethodsA framework for motion correction, including image pre-processing enhancement and rigid registration to an iteratively improved target image, was developed. The proposed method was compared to Motion Correction with FMRIB’s Linear Image Registration Tool (MCFLIRT) function in FSL over 13 subjects. Native (pre-correction) and residual (post-correction) motions were evaluated by means of markers positioned at well-defined anatomical regions over each image.ResultsBoth motion correction strategies significantly reduced inter-image misalignment, and the MC-MoCo method yielded significantly better results than MCFLIRT.ConclusionMC-MoCo is a high-performance method for motion correction of multi-contrast volumes as in 3D ihMT imaging.

Despite the technological evolutions that transform the operating rooms nowadays, a major clinical need remains: surgeons need to distinguish healthy from diseased tissues while performing a procedure. Tissue status assessment procedures such as blood perfusion monitoring require objective input that can potentially be obtained with fluorescence imaging and oxygenation imaging. We developed a multimodal imaging platform for performing widefield quantitative oxygenation imaging and fluorescence imaging in a clinical environment. We demonstrate in-vivo the impact of widefield quantitative oxygenation imaging on blood perfusion assessment. Fluorescence imaging provided by the system is used in complement to confirm the outcome of oxygenation imaging.

International audience; PurposeTo determine optimal constrained tissue parameters and off-resonance sequence parameters for single-point macromolecular proton fraction (SP-MPF) mapping based on a comprehensive quantitative magnetization transfer (qMT) protocol in healthy and demyelinated living mice at 7T.MethodsUsing 3D spoiled gradient echo-based sequences, a comprehensive qMT protocol is performed by sampling the Z-spectrum of mice brains, in vivo. Provided additional T1, urn:x-wiley:07403194:media:mrm28397:mrm28397-math-0001 and B0 maps allow for the estimation of qMT tissue parameters, among which three will be constrained, namely the longitudinal and transverse relaxation characteristics of the free pool (R1,fT2,f), the cross-relaxation rate (R) and the bound pool transverse relaxation time (T2,r). Different sets of constrained parameters are investigated to reduce the bias between the SP-MPF and its reference based on the comprehensive protocol.ResultsBased on a whole-brain histogram analysis about the constrained parameters, the optimal experimental parameters that minimize the global bias between reference and SP-MPF maps consist of a 600° and 6 kHz off-resonance irradiation pulse. Following a Bland-Altman analysis over regions of interest, optimal constrained parameters were R1,fT2,f = 0.0129, R = 26.5 s−1, and T2,r = 9.1 µs, yielding an overall MPF bias of 10−4 (limits of agreement [−0.0068;0.0070]) and a relative variation of 0.64% ± 5.95% between the reference and the optimal single-point method across all mice.ConclusionThe necessity of estimating animal model- and field-dependent constrained parameters was demonstrated. The single-point MPF method can be reliably applied at 7T, as part of routine preclinical in vivo imaging protocol in mice.

Background High‐dose pharmaceutical‐grade biotin (MD1003) has positive effects on disability in progressive multiple sclerosis (PMS), but its mechanism of action remains unclear. The objective of our study was to quantify the effect of MD1003 in patients with PMS, using clinical response, plasma neurofilament light chain (pNfL) levels, and brain (BV) or cervical spinal cord volume (CSCV). Materials and methods Forty‐eight patients with PMS newly treated with MD1003 were followed during one year. Patients were assessed clinically using the Expanded Disability Status Scale (EDSS), the nine‐hole peg test (9HPT), and the 25‐foot walk time (25FWT). CSCV was quantified using CORDIAL software and BV using SIENA or SIENAX. We measured pNfL level using SIMOA at several time points. Bayesian linear and logistic regressions were used to evaluate potential prognostic factors. Results Treatment response, defined as a significant decrease of EDSS, 25FWT, or 9HPT at 1 year, was observed in 13 patients (27%). A gain of volume was noted in 7/24 patients for brain and in 10/19 patients for cervical spinal cord. The strongest predictors of poor treatment response were a high pNfL level at MD1003 onset (OR 0.96; 95% CI [0.91; 1]), high age at MS onset (OR 0.95; 95% CI [0.89; 1.01]), and an increase in brain lesion load during MD1003 treatment (OR 0.81; 95% CI [0.55; 1.05]). Conclusions MD1003 treatment was associated with clinical, BV, and CSCV improvement at 1 year. The correlation between the levels of pNfL at baseline, the age at multiple sclerosis onset, and a treatment response at M12 is consistent with a better effect in less disabled patients., MD1003 treatment was associated with clinical, brain and cervical spinal cord volumes improvement at 1 year. The correlation between the levels of pNfL at baseline, the age at MS onset and a treatment response at M12 is consistent with a better effect in less disabled patients. Our study provides a set of objective assessments that, taken together, argue for a possible neuroprotective or remyelinating effect of MD1003 in progressive forms of MS.

Background and Purpose Concern has grown about the finding of gadolinium deposits in the brain after administering gadolinium-based contrast agents (GBCAs). The mechanism is unclear, and related questions remain unanswered, including the stability over time. Therefore, we conducted a three-time-point study to explore T1-weighted (W) signal changes in the dentate nucleus (DN) and globus pallidus (GP), after the first, fifth, and tenth injections of either a macrocyclic agent (gadoterate meglumine) or a linear agent (gadobenate dimeglumine). Materials and methods For this retrospective, multicenter, longitudinal study, two groups of 18 (gadoterate meglumine) and 19 (gadobenate dimeglumine) patients were identified. The evolution of the signal over time was analyzed using DN/pons (DN/P) and GP/thalamus (GP/T) ratios. Results DN/P and GP/T ratios tended to increase after the fifth administration of gadobenate dimeglumine, following by a downward trend. A trend in a decrease in DN/P and GP/T ratios were found after the fifth and tenth administrations of gadoterate meglumine. Conclusion After exposure to gadobenate dimeglumine, the signal intensity (SI) tended to increase after the fifth injection owing to gadolinium accumulation, however, a SI increase was not found after the tenth administration supporting the hypothesis of a slow elimination of the previously retained gadolinium (wash-out effect) from the brain or of a change in form (by dechelation), causing the signal to fade. No increasing SI was found in the DN and GP after exclusive exposure to gadoterate meglumine, thus confirming its stability. We found, instead, a trend for a significative gadolinium elimination over time.

Purpose To introduce a novel method for long-T2 signal physical suppression in steady-state based on configuration states combination and modulation using diffusion weighting. Its efficiency in yielding a high contrast in short-T2 structures using an ultrashort echo time acquisition module (Diff-UTE) is compared to the adiabatically prepared Inversion-Recovery-UTE sequence (IR-UTE). Theory and methods Using a rectangular-pulse prepared 3D-UTE sequence, the possibility of long-T2 component signal cancellation through diffusion effects is addressed, and the condition met for sets of sequence parameters. Simultaneously, the short-T2 component signal is maximized using a Bloch equation-based optimization process. The method is evaluated from simulations, and experiments are conducted on a phantom composed of short and long-T2 components, as well as on an ex vivo mouse head. Results Within equal scan times, the proposed method allowed for an efficient long-T2 signal suppression, and expectedly yielded a higher signal to noise ratio in short-T2 structures compared to the IR-UTE technique, although an intrinsic short-T2 signal loss is expected through the preparation module. Conclusion The Diff-UTE method represents an interesting alternative to the IR-UTE technique. Diffusion weighting allowing for a long-T2 suppression results in a less penalizing method to generate a high and selective contrast in short-T2 components. Magn Reson Med 80:548-559, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Introduction La catatonie periodique (KP) est un des phenotypes de psychose endogene le plus frequent, souvent responsable d’un handicap severe. Elle se caracterise par une desorganisation des processus psychomoteurs dont la semeiologie est peu maitrisee par les psychiatres et difficile a quantifier en raison d’un parasitage de la clinique par les traitements neuroleptiques. La mise au point d’un biomarqueur changerait radicalement la donne. Deux etudes de groupe, ont mis en evidence une hyper-perfusion de l’aire motrice supplementaire G (AMS-G) et la region premotrice G (PM-G) dans la KP comparativement non seulement a des temoins, mais aussi a des patients non-KP, traites par les memes medicaments. Dans cette etude, nous voulons determiner si cet hyper-debit peut constituer un biomarqueur de la KP. Materiels et methodes Dix patients KP (9 certains, 1 douteux) et 26 patients non-KP (23 depressions resistantes, 3 catatonies manierees) ont ete inclus. Les sujets ont beneficie d’une serie de 3 IRM ASL sur une IRM 3 T (Verio, SIEMENS, sequence QIPSS II) au cours de differentes tâches cognitives, selon deux modalites : ASL pure avec un TE de 9,7 ms et ASL-BOLD avec un TE de 21 ms. Le signal ASL etait converti en equivalent debit sanguin (rCBF). Les 3 cartes par modalite etaient comparees a une base de 40 temoins par un test t. Nous avons trace les courbes ROC pour les regions qui ressortaient des etudes precedentes : AMS-G (−12, +5, +66) et PM-G (−55, −8, +47) et cartographie l’indice de Youden. La sensibilite et la specificite de la presence de cet hyper-debit chez les patients KP ont ete estimees avec une analyse bayesienne en utilisant des fonctions beta et des a priori peu informatifs. Resultats La cartographie de l’indice de Youden pour t > 2,4 (soit p Conclusion Ces resultats preliminaires sont encourageants et devront etre confirmes par une nouvelle etude cherchant a reduire a 2 le nombre d’IRM necessaire.

Background Emotional disturbances in multiple sclerosis (MS) are often explored in terms of affect recognition, with controversial results that likely reflect the high lesional heterogeneity. Patients' emotional experience, however, has seldom been studied and has never been explored using fMRI. Objectives To explore the emotional experience in MS and compare these data with fMRI measurements using for the first time real-life emotional scenes differing in valence and arousal. Methods Twenty-five right-handed women with relapsing-remitting MS and 27 right-handed age-, sex-, and education-matched healthy controls visualized during an fMRI session, emotional scenes taken from the international affect picture system (IAPS) and differing in valence (positive, negative, neutral) and arousal (ranging from calm to excited). During a post-scanning debriefing, participants were asked to look again at each image and score it in terms of valence and arousal sensation on a scale of 1–9. Results Cognitively well-preserved MS subjects presented a significantly more scattered emotional experience compared to controls in response to positive and negative pictures. In fMRI, MS patients also presented a higher variability of response when compared to controls in left inferior orbitofrontal cortex for positive stimulations. For negative condition, no significant results were observed between the two groups. However, a trend was detected in left amygdala, right fusiform gyrus, right caudate nucleus and right pallidum for negative stimulations. Conclusion In response to emotional stimuli, MS subjects presented a scattered emotional experience subtended by a greater variability of brain response, highlighting an emotional pattern not previously reported in MS patients.

Periodic catatonia (PC) is a psychomotor phenotype with a progressive-remitting course. While it can fit any disorder diagnosis of the schizoaffective spectrum, its core features consist of a mix of hypo- and hyperkinesias resulting in distortions of expressive movements such as grimacing and parakinesias. The replication of cerebral blood flow (CBF) increases in the left supplementary motor area (L-SMA) and lateral premotor cortex (L-LPM) in acute and remitting PC patients indicates that these increases could be used as diagnostic biomarkers. In this proof-of-concept study, 2 different MRI sequences were repeated on 3 separate days to get reliable measurement values of CBF in 9 PC and 26 non-PC patients during different cognitive tasks. Each patient was compared to 37 controls. In L-SMA [–9; +10; +60] and L-LPM [–46; –12; +43], a test was positive if the t value was >2.02 (α < 0.05; two tailed). The measurements had good analytical performance. Regarding the tests, their sensitivities and specificities were significantly different from the chance level on both measures, except for L-SMA sensitivities. When combining all the tests, among regions and methods, sensitivity was 98% (95% credible interval [CI] 76–100%) and specificity 88% (72–97%). Bayesian inferences of its negative predictive values for PC were >95% regardless of the context, while its positive predictive values reached 94% but only when used in combination with clinical criteria. The case-by-case analysis suggests that non-PC patients with neurological motor deficits are at risk to be false positive.

International audience; Myelin imaging in the central nervous system is essential for monitoring pathologies involving white matter alterations. Various quantitative MRI protocols relying on the modeling of the interactions of water protons with myelinated tissues have shown sensitivities in case of myelin disruption. Some extracted model parameters are more sensitive to demyelination, such as the bound pool fraction (f) in quantitative magnetization transfer imaging (qMTI), the radial diffusivity in diffusion tensor imaging (DTI), and the myelin water fraction (MWF) in myelin water imaging (MWI). A 3D ultrashort echo time (UTE) sequence within an appropriate water suppression condition (Diff-UTE) is also considered for the direct visualization of the myelin semi-solid matrix (Diff-UTE normalized signal; rSPF). In this paper, we aimed at assessing the sensitivities and correlations of the parameters mentioned above to an immuno-histological study of the Myelin Basic Protein (MBP) in a murine model of demyelination at 7 T. We demonstrated a high sensitivity of the MRI metrics to demyelination, and strong Spearman correlations in the corpus callosum between histology, macromolecular proton fraction (ρ > 0.87) and Diff-UTE signal (ρ > 0.76), but moderate ones with radial diffusivity and MWF (|ρ| < 0.70).

Introduction Plusieurs evaluations de routine (EDSS, poussees, IRM) sont predictives de l’efficacite des traitements dans la sclerose en plaques recurrente-remittente (SEP RR). Cependant, une evaluation multimodale fine a peu ete etudiee. Objectifs Evaluer l’interet de plusieurs evaluations non pratiquees en routine sur le recours a un traitement de 2e ligne chez des patients sous interferon β-1a (IFN) ou acetate de glatiramere (AG). Patients et methodes Il s’agit d’une etude observationnelle multicentrique prospective. Nous avons inclus les adultes avec une SEP RR ayant debute un traitement par IFN ou AG. Le critere de jugement principal etait le recours a une 2e ligne (natalizumab, ocrelizumab, fingolimod, alemtuzumab) au cours du suivi. L’evaluation initiale comprenait un score EDSS, un bilan neuropsychologique (BcCog), un test de marche (25TWT), un test de dexterite manuelle (9HPT), un OCT (tomographie en coherence optique) et une volumetrie cerebrale. Resultats Nous avons inclus 78 patients de 3 centres expert SEP (Strasbourg, Nancy et Lille) entre mars 2009 et septembre 2011. L’âge moyen etait de 36,4 ans (± 12) et 70,5 % etaient des femmes. Les patients etaient traites par IFN (73,1 %) ou AG (26,9 %). Le temps moyen de suivi etait de 82,4 mois. Trente-trois patients (42,3 %) ont eu recours a une 2e ligne de traitement. La proportion de patient en NEDA-3 a 2 ans etait de 35,6 %. Discussion Des donnees supplementaires pour predire plus finement la reponse therapeutique sont necessaires car le recours a une 2e ligne de traitement n’est pas rare. Les valeurs predictives des differentes evaluations seront presentees lors du congres. Conclusion Le recours a une 2e ligne de traitement etait necessaire chez plus d’un tiers des patients sous IFN ou AG.

International audience; Introduction: Magnetic resonance imaging (MRI) shows slight spatial variations in brain white matter (WM). We used quantitative multi-parametric MRI to evaluate in what respect these inhomogeneities could correspond to WM subtypes with specific characteristics and spatial distribution.Materials and methods: Twenty-six controls (12 women, 38 ±9 Y) took part in a 60-min session on a 3T scanner measuring 7 parameters: R1 and R2, diffusion tensor imaging which allowed to measure Axial and Radial Diffusivity (AD, RD), magnetization transfer imaging which enabled to compute the Macromolecular Proton Fraction (MPF), and a susceptibility-weighted sequence which permitted to quantify R2* and magnetic susceptibility (χm). Spatial independent component analysis was used to identify WM subtypes with specific combination of quantitative parameters values.Results: Three subtypes could be identified. t-WM (track) mostly mapped on well-formed projection and commissural tracts and came with high AD values (all p < 10−18). The two other subtypes were located in subcortical WM and overlapped with association fibers: f-WM (frontal) was mostly anterior in the frontal lobe whereas c-WM (central) was underneath the central cortex. f-WM and c-WM had higher MPF values, indicating a higher myelin content (all p < 1.7 10−6). This was compatible with their larger χm and R2, as iron is essentially stored in oligodendrocytes (all p < 0.01). Although R1 essentially showed the same, its higher value in t-WM relative to c-WM might be related to its higher cholesterol concentration.Conclusions: Thus, f- and c-WMs were less structured, but more myelinated and probably more metabolically active regarding to their iron content than WM related to fasciculi (t-WM). As known WM bundles passed though different WM subtypes, myelination might not be uniform along the axons but rather follow a spatially consistent regional variability. Future studies might examine the reproducibility of this decomposition and how development and pathology differently affect each subtype.

Introduction Les troubles emotionnels sont frequemment evoques dans la sclerose en plaques (SEP) mais avec des resultats parfois contradictoires qui sont probablement le reflet de l’heterogeneite lesionnelle inherente a la maladie. Objectifs Explorer l’experience emotionnelle positive et negative dans la SEP dans une etude en IRMf, en prenant en compte la variabilite clinique qu’induit cette pathologie. Methodes Vingt-cinq femmes droitieres atteintes de la SEP et 27 sujets temoins apparies en âge, sexe et niveau d’education regardent durant l’IRMf des scenes emotionnelles qui different en valence (positive, negative, neutre) et en intensite (faible a forte). Une analyse par regions d’interets permet d’etudier le signal moyen et sa variabilite. Un debriefing survient apres l’IRMf ou le sujet revoit chaque image et cote son experience emotionnelle subjective. A ceci s’ajoute un bilan cognitif complet. Resultats Des patientes bien preservees sur le plan cognitif presentent une experience emotionnelle tres dispersee par rapport aux sujets controles. Une importante variabilite du signal hemodynamique est par ailleurs observee chez nos patientes par rapport aux temoins dans le cortex orbito-frontal gauche lors de la visualisation d’images positives, et dans l’amygdale gauche, le gyrus fusiforme, le noyau caude et le pallidum droits pour les images negatives. Discussion Lors de la visualisation d’images positives et negatives, d’anormales activations cerebrales sont reperees dans des structures qui sont connues pour etre directement impliquees dans la genese des emotions ou indirectement a travers une modulation sensorielle du stimulius emotionnel. Ces donnees contribuent a l’emergence d’une experience emotionnelle modifiee dans la SEP. Conclusion Les patients atteints de la SEP presentent une experience emotionnelle tres dispersee qui semble sous-tendue par une mobilisation heterogene de regions impliquees dans ces processus emotionnels.

Background Neuromyelitis optica (NMO) is an inflammatory disease involving predominantly the spinal cord and optic nerves. Whether patients with NMO have a loss in white or grey matter (GM) volumes remains to be determined. Methods Thirty patients with NMO, 30 healthy subjects matched for age and gender, 21 patients with multiple sclerosis (MS) and 20 patients with a clinically isolated syndrome (CIS) were studied. We applied a SIENAX post-treatment software. We compared white matter (WM) and GM volumes between groups and explored correlations of changes in NMO patients with age, gender, duration, disease severity, visual acuity and T2 hyperintensities. We also performed a voxel-based morphometry (VBM) analysis to identify the regions affected by loss of volume. Results White matter volume was significantly reduced in patients with NMO (764.4 ± 58.3 cm3) compared to healthy subjects (843.1 ± 49.3 cm3) (P

Introduction Les troubles emotionnels sont frequemment observes dans l’alexithymie et dans la sclerose en plaques (SEP) avec de memes anomalies fronto-sous-corticales. Or l’alexithymie est un trouble tres frequent dans la SEP. Objectifs Comprendre la contribution de l’alexithymie dans les troubles emotionnels observes dans la SEP, sur le plan de l’experience emotionnelle et de ses sous-bassement neurobiologiques. Methodes Douze femmes alexithymiques et 12 femmes non alexitymiques atteintes de la scleroses en plaques ont ete appariees a 27 femmes controles saines. Lors de l’IRMf, les sujets visualisent des scenes emotionnelles qui different en valence (positives, negatives, neutres) et en intensite (forte a faible). Le recueil du ressenti subjectif engendre par l’experience emotionnelle a lieu en dehors de l’IRM avec une cotation de la valence et de l’intensite sur une echelle de 1 a 10. Resultats Le vecu subjectif est similaire entre les trois groupes. Cependant, face a des scenes visuelles positives, les patientes alexithymiques hypoactivent l’insula et les zones temporales par rapport aux temoins et aux patientes non alexithymiques. Face a des scenes visuelles negatives, elles hypoactivent le cortex cingulaire anterieur, le corps calleux et le gyrus temporal moyen gauche par rapport aux temoins. Le groupe temoin et SEP non alexithymique ne different pas dans leur patterns d’activation. Discussion Malgre une experience similaire sur le plan du vecu subjectif ressenti, les regions cerebrales supportant l’experience hedonique sont specifiquement modulees par l’alexithymie co-morbide a la sclerose en plaques, tandis que l’experience anhedonique semble etre influencee par la maladie et l’alexithymie. Conclusion L’alexithymie influence les emotions dans la SEP ; il parait donc important de prendre cet aspect en consideration lors des etudes portant sur la cognition sociale dans la SEP.

There is a real need in the neuroscience community for efficient tools to compare Diffusion Tensor Magnetic Resonance Imaging across cohorts of subjects. Most studies focus on the comparison of scalar images such as fractional anisotropy or mean diffusivity. Although different statistical frameworks have been proposed to compare the whole diffusion tensor information, they are still seldom used in neuroimaging studies. In this paper, we investigate on both simulated and real data whether there is a real added value of considering the whole tensor information for conducting voxel-based group studies. Then, we compare two statistical tests dedicated to tensor, namely the Cramer test and a tensor-based extension of the General Linear Model (GLM), the latter presenting the advantage to account for covariates. We also evaluate the impact of different metrics (Euclidean, Log-Euclidean and affine-invariant Riemannian metrics) for estimating the GLM parameters. Finally, we address the problem of interpreting the change detection maps obtained by tensor-based methods by proposing a way to characterize each of the detected clusters according to several scalar indices. Our study suggests that if there is no prior assumption about the nature of the expected changes, it is really preferable to use tensor-based rather than scalar-based statistical analysis. The Cramer test can advantageously be used when no confounding variable hampers the group comparison, otherwise the GLM should be considered. Finally, the different metrics show similar performance in the real scenario, with a significant computational overhead for the Riemannian framework.

Objectives To assess and compare cortical thickness (CTh) of patients with prodromal Dementia with Lewy bodies (pro-DLB), prodromal Alzheimer's disease (pro-AD), DLB dementia (DLB-d), AD dementia (AD-d) and normal ageing. Methods Study participants(28 pro-DLB, 27 pro-AD, 31 DLB-d, 54 AD-d and 33 elderly controls) underwent 3Tesla T1 3D MRI and detailed clinical and cognitive assessments. We used FreeSurfer analysis package to measure CTh and investigate patterns of cortical thinning across groups. Results Comparison of CTh between pro-DLB and pro-AD (p

Diffusion Tensor Magnetic Resonance Imaging DT-MRI is a modality which allows to investigate the white matter structure by probing water molecule diffusion. A common way to model the diffusion process is to consider a second-order tensor, represented by a symmetric positive-definite matrix. Currently, there is still no consensus on the most appropriate manifold for handling diffusion tensors. We propose to evaluate the influence of considering an Euclidean, a Log-Euclidean or a Riemannian manifold for conducting group comparison in DT-MRI. To this end, we consider a multi-linear regression problem that is solved on each of these manifolds. Statistical analysis is then achieved by computing an F-statistic between two nested restricted and full models. Our evaluation on simulated data suggests that the performance of these manifolds varies with the kind of modifications that has to be detected, while the experiments on real data do not exhibit significant difference between the methods.

Virtual colonoscopy is a mini-invasive technique for early detection of colorectal polyps. We present here a method for automated colon lumen and colonic polyps segmentation from MR images. The contrast between the colon lumen and neighboring tissues is sucien t so that the lumen can be segmented based on its intensity, but morphological operators and geometrical tools must be used for polyp detection. R esum e. La coloscopie virtuelle est un technique mini-invasive permettant une d etection pr ecoce des polypes colorectaux. Nous pr esentons ici une m ethode permettant de segmenter automatiquement la lumi ere du c^ olon ainsi que les polypes pr esents dans celui-ci a partir d'images IRM. Si le contraste entre la lumi ere du c^ olon et les tissus voisins est susan t pour que celle-ci puisse ^ segment ee uniquement gr^ ace a des crit eres d'intensit e, des op erateurs morphologiques et des outils g eom etriques sont utilis es pour d etecter automatiquement les polypes.

Objectif Rechercher la presence d’un hypersignal T1 dans les noyaux denteles de patients ayant recu plus de 5 injections de Dotarem et suivis pour une pathologie n’entrainant pas de rupture de la barriere hemato-encephalique (BHE), a savoir une tumeur du conduit auditif interne (CAI). Utilisation pour cela d’une methode automatique de segmentation des noyaux denteles (ND) et du pont. Materiel et methodes Etude retrospective menee au CHU de Strasbourg d’octobre 2015 a juillet 2016, sur une IRM Signa HDX 3T GE healthcare . Au total sur 1063 IRM des CAI realisees durant cette periode, les IRM de 15 patients ayant recu plus de 5 injections avec exclusivement du Dotarem ont ete comparees avec celles de 14 temoins, apparies en âge et en sexe et n’ayant jamais recu de produit de contraste. Les patients avec une insuffisance renale ou une insuffisance hepatique ont ete exclus. Le nombre moyen d’injection etait de 5,73 injections ± 0,96 et le volume moyen injecte etait de 76,4 ml ± 23,7. La segmentation automatisee des noyaux denteles et du pont a ete realise par transport de carte apres recalage sur l’atlas cerebral SPL ( Fig. 1 ). Les ratios d’intensite moyenne de signal noyaux denteles/pont ont ete compares avec un test de Mann-Whitney. Resultats La moyenne du ratio ND/pont chez les patients exposes a plus de 5 injections est de 1,0873 ± 0,1043 et pour le groupe temoin de 1,0578 ± 0,1173. Cette difference n’est pas statistiquement significative p = 0,525, IC a 95 % (–0,089 ; 0,059) ( Fig. 2 ). Conclusion L’administration repetee de Dotarem ne semble donc pas entrainer d’hypersignal T1 des noyaux denteles chez les patients suivis pour une tumeur des CAI. La segmentation automatique des noyaux denteles et du pont peut apporter une aide interessante dans la recherche de ces depots.

Our purpose in this short study is to propose an enquiry concerning the Gaston Bachelard’s philosophy of science, whose principal axes are representative of the so called French tradition of epistemology. We will fol-low the guiding principles of the bachelardian’s epistemology. Their attentive analysis will make us able to examine in a detailed and a thorough way the scientific phenomena construction, considering its complexity and the intri-cacy of its elements. With this in prospect, it will be necessary to display the analysis of the scientific phenomena following the integration, in an open ra-tionalism, of the study concerning relations between science and philosophy, the question of the epistemic subject, dialectical relations between theory and experience, within the framework of a fundamental incompletion of human knowledge.

The teniae coli, three longitudinal bands of muscle on the colon surface, are important anatomical structures for several virtual colonoscopy applications: colon registration, virtual dissection, navigation and polyp matching. The current detection method involves manually tracing one of the teniae on the colon surface, a long and error-prone process. In this paper, we present a semi-automated detection method, which only requires the user to reconnect a few long segments of teniae. This method is based on local parameterizations of the colon surface, and on the application of classical image processing algorithms on the graph created by the triangular mesh of the surface. The results, computed on four test cases, are promising.

CT colonography, a prevalent tool to diagnose colon cancer in its early stages, is often limited by bad distention, or retained fluids, which will cause segments of the colon to be impossible to process by CAD tools. By scanning patients in both prone and supine positions, collapsed segments and retained fluids will not be in the same place in both images, increasing the length of the colon that can be processed correctly. In order to fully use these two scans, they must be registered, so that a lesion identified on one of them can be mapped to the other, thus increasing sensitivity and specificity of CAD tools. The surface of the colon is however large (more than half a million vertices on our images), and has no canonical shape, which makes atlases and other widely used registration algorithms non optimal. We present in this paper a fast method to register the colon surface between prone and supine scans using landmarks present on the colon, the teniae coli. Our method is composed of three steps. First, we register the body, based on manually placed landmarks. Then we register the three tenit coli, and, from this registration, we compute a deformation field for each vertex of the colon surface. We tested our method on 5 cases, by measuring the RMS error after body registration, quantifying the intrisic movement of the colon, and after colon surface registration. The RMS error was reduced from 1.8 cm to 0.49 cm, a reduction of 71%.

This documents describes a set of classes to integrate digital topology in the Insight Toolkit, with an application to homotopic thinning. The skeletonization filter implemented using our set of classes is twice as fast as BinaryThinningImageFilter and can be used on images of any dimension.

The paper describes a software method to extend ITK (Insight ToolKit, supported by the National Library of Medicine), leading to ITK++. This method, which is based on the extension of the iterator design pattern, allows the processing of regions of interest with arbitrary shapes, without modifying the existing ITK code. We experimentally evaluate this work by considering the practical case of the liver vessel segmentation from CT-scan images, where it is pertinent to constrain processings to the liver area. Experimental results clearly prove the interest of this work: for instance, the anisotropic filtering of this area is performed in only 16@?s with our proposed solution, while it takes 52@?s using the native ITK framework. A major advantage of this method is that only add-ons are performed: this facilitates the further evaluation of ITK++ while preserving the native ITK framework.

The central path of the colon is an important tool in computer-assisted diagnosis: it is an aid to navigation during a virtual colonoscopy and allows an easier follow-up of the patient pathologies. However the computation of this central path remains a difficult task: on both MR and CT medical images, the wall of the colon is too thin with respect to the resolution of the acquisition and thus does not appear on images. Hence, when two sections of the colon are in contact, a loop is created in the image, and causes a wrong central path. In this paper, we propose an algorithm to remove those loops, based on the tracking of the colon skeleton in a scale-space. An evaluation of our algorithm on 20 patients showed that every loop was successfully removed, yielding a centered, anatomically and topologically correct central path.