Vincent Perlbarg | UPMC Sorbonne Universités (original) (raw)

Papers by Vincent Perlbarg

International Journal of Biomedical Imaging, 2008

A large-scale brain network can be defined as a set of segregated and integrated regions, that is... more A large-scale brain network can be defined as a set of segregated and integrated regions, that is, distant regions that share strong anatomical connections and functional interactions. Data-driven investigation of such networks has recently received a great deal of attention in blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI). We here review the rationale for such an investigation, the methods used, the results obtained, and also discuss some issues that have to be faced for an efficient exploration.

Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has been extensi... more Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has been extensively used to study how task performance modulates brain activity. Such an approach emphasizes the principle of functional segregation, in that different brain areas are characterized by their involvement in specific cognitive processes. However, this type of analysis essentially ignores that the brain maintains a constant level of spontaneous activity, i.e., activity that is not a direct consequence of environmental stimulations. Investigating these spontaneous brain fluctuations is a challenge precisely because they cannot be controlled by an experimental design. The first successful study of brain spontaneous fluctuations by BOLD fMRI was performed by Biswal and colleagues [3], who computed the correlation between the time course of a seed region and all brain voxels in the absence of any experimental task.

F1000Research, Oct 10, 2014

In this paper, we present an approach for building paths representing the anatomical connections ... more In this paper, we present an approach for building paths representing the anatomical connections between some given regions of the brain. The method combines diffusion tensor imaging (DTI) and fast marching techniques, representing an anatomical connection as the shortest path for some global minimization criterion. Paths are generated by growing level sets, looking for saddle points and backpropagating. We show

HAL (Le Centre pour la Communication Scientifique Directe), Oct 23, 2014

International audienc

$Research paper thumbnail of Long-term outcome after severe traumatic brain injury (TBI) and correlation with volumetry and fractional anisotropy$

Annals of physical and rehabilitation medicine, Sep 1, 2017

Objective: To obtain a comprehensive understanding of long-term outcome after severe traumatic br... more Objective: To obtain a comprehensive understanding of long-term outcome after severe traumatic brain injury (sTBI). Participants: Forty-six patients with sTBI. Design: Comparison of interdisciplinary evaluation results at discharge from acute care and at 2 to 5 year follow-up. Main Measures: Extended Glasgow Outcome Scale, the FIM TM instrument, and the Neurobehavioral Rating Scale-Revised. Results: Significant improvement was observed on the FIM TM instrument, the Extended Glasgow Outcome Scale, and on 3 factors of the Neurobehavioral Rating Scale-Revised. These measures at discharge were significant predictors of outcome. Conclusion: Patients with sTBI 2 to 5 years postinjury showed relatively good physical and functional outcome but poorer cognitive and emotional outcome.

Journal of Neuroradiology, Mar 1, 2016

... 2003; 19:1349-1360. [5] AT Toosy and al. NeuroImage. 2003; 21:1452-1463. [6] JS Damoiseaux an... more ... 2003; 19:1349-1360. [5] AT Toosy and al. NeuroImage. 2003; 21:1452-1463. [6] JS Damoiseaux and al. PNAS. 2006; 103:13848-13853. [7] TEJ Behrens and al. NeuroImage. 2007; 34:144-155. [8] JL Vincent and al. Nature. 2007; 447:83-86. Fig. 2: Functional networks. ...

Journal De Radiologie, Oct 1, 2008

Objectifs Connaitre les avantages qualitatifs de la realisation des examens SRM a 3 teslas. Conna... more Objectifs Connaitre les avantages qualitatifs de la realisation des examens SRM a 3 teslas. Connaitre ses difficultes de realisation. Connaitre les nouvelles applications de la spetroscopie a haut champ. Points cles Les regles physiques font que les spectres acquis a 3 T doivent theoriquement etre de meilleure qualite qu’a 1,5 T. Sa realisation reste un peu complexe en raison des artefacts frequents. Les rapports metaboliques sont comparables a ceux mesures a 1,5T. L’augmentation du rapport signal/bruit et de la gamme de frequence permettent de nouvelles applications comme la spectro du phosphore ou le GABA edit. Resume La spectroscopie est une des applications IRM qui beneficie le plus d’une realisation a tres haut champ (3T et plus). Par rapport a 1,5T, on peut attendre un signal plus important (pouvant permettre de reduire la duree d’acquisition ou la taille du voxel) ainsi qu’une meilleure separation des pics liee a l’augmentation des deplacements chimiques. Ceci permet par exemple de separer les resonances de la glutamine, du glutamate et du GABA, ouvrant des perspectives interessantes en epileptologie ou en excitotoxicite. La spectroscopie de noyaux autres que l’hydrogene, en particulier le phosphore (qui permet une etude du metabolisme energetique), devient egalement possible moyennant l’utilisation d’antennes dediees. Les rapports metaboliques sont comparables a ceux observes 1,5T, ce qui permet une interpretation simple des examens en routine clinique. La principale limite est l’augmentation des artefacts, conduisant a un taux d’echecs techniques plus important qu’a plus bas champ.

In functional magnetic resonance imaging (fMRI), cerebral activity has been increasingly consider... more In functional magnetic resonance imaging (fMRI), cerebral activity has been increasingly considered as the consequence of a network activation. Selecting the brain regions relevant for the network has thus become a key issue. We propose to define the so-called large-scale functional network involved in a particular task as a set of regions exhibiting strong intrinsic homogeneity, as well as at least one strong longdistance interregional interaction. We develop a method to identify such a network, and we validate it on a real dataset, in a context where the existence of a distributed network has already been demonstrated. Our results are compatible with previous studies. This new tool is thus promising for selecting regions when analyzing functional connectivity in fMRI.

In functional magnetic resonance imaging, functional connectivity of brain regions is defined as ... more In functional magnetic resonance imaging, functional connectivity of brain regions is defined as the temporal correlation of their average time courses. A key question is to determine which processes contribute to functional connectivity. Independent Component Analysis (ICA) is a recent data-driven method that has proven efficient to identify activation and a number of artefacts. We propose a flexible model to explain the functional connectivity in a network of brain regions. The method we propose is based on matching pursuit to select a small set of independent components calculated by ICA that explains most correlations in a given network. On a real dataset, we show that the number of components is small enough to allow for a systematic qualitative interpretation of the selected components. Our results suggest that functional connectivity is not only due to the activation signal and artefacts, but also to other components, sharing similarity with resting-state signal.

Research Square (Research Square), May 12, 2022

Title: Memory impairment associated with Papez circuit lesions in patients with severe traumatic ... more Title: Memory impairment associated with Papez circuit lesions in patients with severe traumatic brain injury assessed by diffuse tensor imaging and volumetric MRI analysis.

Journal of Computer Assisted Tomography, Mar 1, 2022

Objective:to assess if quantitative diffusion MRI analysis would improve prognostication of indiv... more Objective:to assess if quantitative diffusion MRI analysis would improve prognostication of individual patients with severe traumatic brain injury.Methods:we analyzed images of 30 healthy controls to extract normal Fractional Anisotropy (FA) ranges along 18 white-matter tracts. Then, we analyzed images of 33 patients, compared their FA values with normal ranges extracted from controls, and computed severity of injury to white-matter tracts. We also asked two neuroradiologists to rate severity of injury to different brain regions on FLAIR and SWI images. Finally, we built three models: 1) fed with neuroradiologists’ ratings; 2) fed with white-matter injury measures; and 3) fed with both input types.Results:the three models respectively predicted survival at 1 year with accuracies of 70%, 73%, and 88%. The accuracy with both input types was significantly better (P<0.05).Conclusion:quantifying severity of injury to white-matter tracts complements qualitative imaging findings and improves outcome prediction in severe traumatic brain injury.

Revue Neurologique, Apr 1, 2022

Journal of Neuroradiology, Mar 1, 2019

Alzheimers & Dementia, Jul 1, 2016

Background: Being clinically diagnosed with a mild cognitive impairment (MCI) due to Alzheimer's ... more Background: Being clinically diagnosed with a mild cognitive impairment (MCI) due to Alzheimer's disease (AD) is widely studied. Yet, the clinical and structural neuroimaging characteristics for prodromal AD, which are defined as A+T+MCI based on the AT (N) system are still highly desirable. This study evaluates the differences of the cognitive assessments and structural magnetic resonance imaging (MRI) between the early MCI (EMCI) and late MCI (LMCI) participants based on the AT (N) system. The potential clinical value of the structural MRI as a predictor of cognitive decline during follow-up in prodromal AD is further investigated. Methods: A total of 406 MCI participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database were chosen and dichotomized into EMCI and LMCI groups according to the Second Edition (Logical Memory II) Wechsler Memory Scale. Multiple markers' data was collected, including age, sex, years of education, ApoE4 status, cerebrospinal fluid (CSF) biomarkers, standardized uptake values ratios (SUVR) means of florbetapir-PET-AV45, cognitive measures, and structural MRI. We chose 197 A+T+MCI participants (prodromal AD) with positive biomarkers of Aβ plaques (labeled "A") and fibrillar tau (labeled "T"). We diagnosed Aβ plaques positive by the SUVR means of florbetapir-PET-AV45 (cut-off >1.1) and fibrillar tau positive by CSF phosphorylated-tau at threonine 181 (p-tau) (cut-off >23 pg/mL). The differences of cognitive assessments and regions of interest (ROIs) defined on the MRI template between EMCI and LMCI were compared. Furthermore, the potential clinical utility of the MRI as the predictor of cognitive decline in prodromal AD was evaluated by investigating the relationship between baseline MRI markers and cognition decline at the follow-up period, through a linear regression model. Results: The LMCI participants had a significantly more amyloid burden and CSF levels of total t-tau than the EMCI participants. The LMCI participants scored a lower result than the EMCI group in the global cognition scales and subscales which included tests for memory, delayed recall memory, executive function, language, attention and visuospatial skills. The cognition levels declined faster in the LMCI participants during the 12-and 24-month follow-up. There were significant differences in ROIs on the structural MRI between the two groups, including a bilateral entorhinal, a bilateral hippocampus, a bilateral amygdala, a bilateral lateral ventricle and cingulate, a corpus callosum, and a left temporal. The thickness average of the left entorhinal, the left middle temporal, the left superior temporal, and the right isthmus cingulate was a * Data used in preparation of this article was obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database (adni.loni.usc.edu).

Anesthésie & Réanimation, Sep 1, 2015

Introduction Le traumatisme crânien (TC) est un probleme majeur de sante publique par sa frequenc... more Introduction Le traumatisme crânien (TC) est un probleme majeur de sante publique par sa frequence, la gravite du pronostic vital immediat et l’importance des sequelles [1] . L’imagerie par resonance magnetique (IRM) avec la mesure de la fraction d’anisotropie (FA) et de la diffusibilite moyenne (MD) en tenseur de diffusion (DTI) apporte une evaluation de l’atteinte de la substance blanche qui peut persister a distance [2] , [3] . L’objectif de cette etude etait de decrire le devenir de traumatises crâniens graves (TCG) de la prise en charge en reanimation a leur evolution neuropsychologique et IRM a plus de 5 ans du TC. Materiel et methodes Etude monocentrique observationnelle. La population selectionnee etait issue d’une cohorte de TCG adultes hospitalises en neuro-reanimation entre 2005 et 2008. Dans le cadre du suivi systematique des TCG, une hospitalisation de jour etait proposee par telephone a chaque patient, afin de realiser un entretien medical pour evaluer leur devenir global et cognitif, un bilan neuropsychologique et une IRM-DTI avec mesures de FA et de MD, au minimum 5 ans apres le TC. Les resultats sont exprimes en effectifs et pourcentages. Les valeurs de FA, de MD et de volumes cerebraux etaient normalisees par rapport a celles de volontaires sains et exprimes en pourcentage de la valeur des controles. Resultats Vingt-deux TC, principalement lies a des AVP (64 %) et a des chutes (23 %) ont ete inclus. A plus de 5 ans, 41 % des patients avaient une bonne recuperation (GOSE 7–8), 46 % un handicap modere (GOSE 5-6) et 13 % un handicap severe (GOSE 3–4). Ils presentaient des troubles cognitifs domines par des syndromes dysexecutifs (100 %), des troubles de l’attention (91 %) et mnesiques (73 %). Ils souffraient d’une atrophie cerebrale avec perte de volume cerebral de 13 % en moyenne et de lesions de la substance blanche visible en IRM-DTI refletant la perte axonale et neuronale. On observait une baisse de FA et une augmentation de MD sur la quasi-totalite des regions etudiees quelle que soit la gravite du TC initial appreciee par le Glasgow Coma Scale, le mecanisme lesionnel ou l’aspect du scanner initial (cf Fig. 1 ). En moyenne, on observait des valeurs de FA a 93 % et de MD a 107 % des controles. Ces modifications de FA et MD etaient significativement plus importantes chez les patients âges de plus de 40 ans au moment du TC et chez ceux qui avaient presente de l’hypertension intracrânienne malgre un traitement bien conduit. Discussion A plus de 5 ans, nous observons des sequelles tant neuropsychologiques que quantifiables a l’IRM chez les victimes d’un TCG hospitalises en reanimation quelle que soit la gravite initiale du TC. Les outils tels que l’IRM-DTI aident a ameliorer notre comprehension du « syndrome TC ». L’existence d’une pathologie degenerative se poursuivant apres le TC initial invite a rechercher de nouvelles pistes therapeutiques visant a limiter ces phenomenes. Nos resultats sont a confirmer par des etudes longitudinales portant sur de grandes series.

The physiological fluctuations (breathing and heartbeat) and brain movements are the main sources... more The physiological fluctuations (breathing and heartbeat) and brain movements are the main sources of confounds in activation and functional connectivity studies in functional magnetic resonance imaging (fMRI). The main difficulty to cope with these effects is the aliasing of cardiac and possible respiration signals for acquisitions with long TR (typically TR &gt; 1s). We proposed a method of structured noise

Alzheimers & Dementia, Jul 1, 2012

Introduction Strong evidence of neurobiological effects in clinical trials could facilitate the d... more Introduction Strong evidence of neurobiological effects in clinical trials could facilitate the development of new treatments for Alzheimer’s disease. It is expected that cohorts of ~100 prodromal subjects per arm are required to obtain significant results with both vMRI and more recently developed methods such as Diffusion Tensor Imaging (DTI) and resting state functional Magnetic Resonance Imaging (rs-fMRI). For time-efficient trial execution, multi-center studies are required to provide rapid enrollment, however the collection of robust data across different scanner types and is essential. The second phase of the Alzheimer’s Disease Neuroimaging Initiative (ADNI-2) has established 3T DTI and rs-fMRI sequence parameters for GE and Philips systems only, respectively. Our objective was to implement these sequences on Philips, Siemens, and GE scanners and to evaluate their consistency prior to their use in a multi-center clinical trial.