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Application of fMRI in clinical situations
Linköping University, Department of Neuroscience and Locomotion. Linköping University, Department of Biomedical Engineering, Center for Medical Image Science and Visualization. Linköping University, Faculty of Health Sciences.
2006 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Since its discovery in the early 1990's functional MRI (fMRI) has become the most widely used technique for mapping of brain functions. Its non-invasiveness and the large number of MR-scanners have contributed to the popularity of fMRI. In recent years the interest in using fMRI as a clinical instrument has increased, primarily for pre-operative planning. The purpose of this work is to improve the applicability of fMRI to clinical situations.

In order to attain the objectives the capacity of analysis methods for fMRI was evaluated, design of paradigms to suit patients was looked into and the effects of an anxiolytic was investigated.

Especially when fMRI is used in the clinic it is crucial that the analysis method employed is sensitive and reliable. It was confirmed that the method developed by Friman et al. is a worthy competitor to other analysis methods. In general the abilities of patients are reduced compared with healthy volunteer subjects. Therefore one has to design the tasks and task instructions to be readily comprehensible. In addition it is not uncommon that patients are anxious before the examinations and the unfamiliar environment in the MR department. Some need a small dose of an anxiolytic to be able to undergo the examination. The effect of an anxiolytic on healthy volunteers was evaluated. No effects on the fMRI results was identified but the results were confounded by a large session effect.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2006. , 83 p.
Series
Linköping Studies in Health Sciences. Thesis, ISSN 1100-6013 ; 76
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-36015Local ID: 29386ISBN: 91-85497-79-7 (print)OAI: oai:DiVA.org:liu-36015DiVA: diva2:256863
Presentation
2006-05-02, Wranne-salen, Hälsouniversitet, Linköping, 08:30 (Swedish)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-09-20
List of papers
1. Performance of canonical correlation analysis in language tests by functional MRI
Open this publication in new window or tab >>Performance of canonical correlation analysis in language tests by functional MRI
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

In this paper a new method based on constraitwd canonical correlation analysis (CCA) for the analysis of fMRI data is evaluated. In particular the method benefits from a powerful way of choosing temporal basis functions in additiou to an adaptive spatial filtering scheme. A modified receiver operating characteristic (ROC) method was used to quantify the results and to compare it with traditionally used statistics in an objective way. The evaluation was performed using real fMRI data form a language test. It was shown that the CCA based method offers a significant gain in detection power.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-97715 (URN)
Available from: 2013-09-20 Created: 2013-09-20 Last updated: 2014-10-02
2. Paradigm design of sensory–motor and language tests in clinical fMRI
Open this publication in new window or tab >>Paradigm design of sensory–motor and language tests in clinical fMRI
2004 (English)In: Neurophysiologie clinique, ISSN 0987-7053, E-ISSN 1769-7131, Vol. 34, no 6, 267-277 p.Article in journal (Refereed) Published
Abstract [en]

Functional magnetic resonance imaging (fMRI) paradigms on sensory–motor and language functions are reviewed from a clinical user’s perspective. The objective was to identify special requirements regarding the design of fMRI paradigms for clinical applications. A wide range of methods for setting up fMRI examinations were found in the literature. It was concluded that there is a need for standardised procedures adapted for clinical settings. Sensory–motor activation patterns do not vary much at different hand motion tasks. Nevertheless it is one of the most important clinical tests. In contrast, the language system is much more complex. In several studies it has been observed that word production tasks are preferable in determination of language lateralisation. Broca’s area is activated by most tasks, whereas sentence processing and semantic decision also involve activation in temporoparietal and frontal areas. However, combined task analysis (CTA) of several different tasks has been found to be more robust and reliable for clinical fMRI compared to separate task analysis.

Abstract [fr]

Les paradigmes utilisés en Imagerie par Résonance Magnétique fonctionnelle (IRMf) pour l’étude des fonctions sensori-motrice et du langage sont passés en revue du point de vue d’un clinicien. L’objectif était de souligner les exigences spéciales nécessaires à la mise en place d’un paradigme d’IRMf dans le cadre d’études cliniques. Un très grand nombre de procédures pour la réalisation d’examens en IRMf existent dans la littérature. Il a été mis en évidence que la mise en place de procédures standardisées, adaptées aux études cliniques était nécessaire. Les patterns d’activation sensori-motrice ne varient pas plus que les tâches de mouvements de la main. Néanmoins c’est l’un des tests les plus importants en pratique clinique. Au contraire, le système du langage est beaucoup plus complexe. Un grand nombre d’études ont montré que l’utilisation de tâches de production de mots était préférable pour étudier la latéralisation du langage. L’aire de Broca est activée par beaucoup de tâches, alors que le traitement des phrases et la décision sémantique entraînent une activation des aires frontales et temporopariétales. Cependant, dans un contexte d’IRMf clinique, l’analyse des tâches combinées de plusieurs tâches différentes est plus robuste et plus fiable que l’analyse des tâches séparées.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-24683 (URN)10.1016/j.neucli.2004.09.006 (DOI)000228731600002 ()6919 (Local ID)6919 (Archive number)6919 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13
3. Influence of diazepam on clinically designed FMRI
Open this publication in new window or tab >>Influence of diazepam on clinically designed FMRI
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2007 (English)In: The Journal of Neuropsychiatry and Clinical Neurosciences, ISSN 0895-0172, E-ISSN 1545-7222, Vol. 19, no 2, 164-172 p.Article in journal (Refereed) Published
Abstract [en]

The authors investigated the effect of diazepam on clinically relevant measures from functional magnetic resonance imaging (fMRI) examinations. Twenty volunteers were scanned twice. Using a double-blind randomized study design, the volunteers received placebo on one occasion, and on the other, 5 mg of diazepam. Three functional tests were used: motor, word generation, and working memory. Images were analyzed individually for each subject and the number of activated voxels and the laterality index were calculated. No significant effects related to the drug were detected. In contrast, the motor and working memory tasks showed a significant decrease in the number of activated voxels between Sessions 1 and 2, independently of diazepam administration. These results indicate that diazepam may be administered for premedication prior to fMRI investigations.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-17989 (URN)10.1176/appi.neuropsych.19.2.164 (DOI)000245666300009 ()17431063 (PubMedID)
Available from: 2009-04-30 Created: 2009-04-30 Last updated: 2017-12-13Bibliographically approved

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Ragnehed, Mattias

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