PMID: identifiant
de la référence Pubmed : |
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 (23096056) |
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| titre : |
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Fast joint detection-estimation of evoked brain activity in event-related fMRI using a variational approach. |
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| auteur(s) : |
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Lotfi Chaari ( ) 1, 2, Thomas Vincent () 1, 2, Florence Forbes () 2, Michel Dojat () 3, Philippe CIUCIU1 |
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| laboratoire : |
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| Équipe de recherche : |
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INSERM U836, équipe 5, Neuroimagerie fonctionnelle et perfusion cérébrale |
| résumé : |
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In standard within-subject analyses of event-related fMRI data, two steps are usually performed separately: detection of brain activity and estimation of the hemodynamic response. Because these two steps are inherently linked, we adopt the socalled region-based Joint Detection-Estimation (JDE) framework that addresses this joint issue using a multivariate inference for detection and estimation. JDE is built by making use of a regional bilinear generative model of the BOLD response and constraining the parameter estimation by physiological priors using temporal and spatial information in a Markovian model. In contrast to previous works that use Markov Chain Monte Carlo (MCMC) techniques to sample the resulting intractable posterior distribution, we recast the JDE into a missing data framework and derive a Variational Expectation-Maximization (VEM) algorithm for its inference. A variational approximation is used to approximate the Markovian model in the unsupervised spatially adaptive JDE inference, which allows automatic fine-tuning of spatial regularization parameters. It provides a new algorithm that exhibits interesting properties in terms of estimation error and computational cost compared to the previously used MCMC-based approach. Experiments on artificial and real data show that VEM-JDE is robust to model misspecification and provides computational gain while maintaining good performance in terms of activation detection and hemodynamic shape recovery. |
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| domaine : |
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langue du texte
intégral : |
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Anglais |
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| ISSN : |
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1558-254X |
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| type de publication : |
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Articles dans des revues avec comité de lecture |
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| DOI : |
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10.1109/TMI.2012.2225636 |
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| journal : |
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| IEEE Transactions on Medical Imaging (IEEE Trans Med Imaging) |
| Publisher |
Institute of Electrical and Electronics Engineers (IEEE) |
| ISSN |
0278-0062 |
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| Audience : |
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internationale |
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| date de publication : |
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19/10/2012 |
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date de publication
électronique : |
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19/10/2012 |
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| page, identifiant, ... : |
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epub ahead of print |
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| mots-clés auteur : |
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Biomedical signal detection-estimation – functional MRI – brain imaging – Joint Detection-Estimation – Markov random field – EM algorithm – Variational approximation |
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