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Functional Magnetic Resonance Imaging for Clinical Diagnosis: Exploring and Improving the Examination Chain
Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology in Linköping. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Functional Magnetic Resonance Imaging (fMRI) is a relatively new imaging technique, first reported in 1992, which enables mapping of brain functions with high spatial resolution. Functionally active areas are distinguished by a small signal increase mediated by changes in local blood oxygenation in response to neural activity. The ability to non-invasively map brain function and the large number of MRI scanners quickly made the method very popular, and fMRI have had a huge impact on the study of brain function, both in healthy and diseased subjects.

The most common clinical application of fMRI is pre-surgical mapping of brain functions in order to optimise surgical interventions. The clinical fMRI examination procedure can be divided into four integrated parts: (1) patient preparation, (2) image acquisition, (3) image analysis and (4) clinical decision. In this thesis, important aspects of all parts of the fMRI examination procedure are explored with the aim to provide recommendations and methods for prosperous clinical usage of the technique.

The most important results of the thesis were: (I) administration of low doses of diazepam to reduce anxiety did not invalidate fMRI mapping results of primary motor and language areas, (II) the choice of visual stimuli equipment can have severe impact on the mapping of visual areas, (III) three-dimensional fMRI imaging sequences did not perform better than two-dimensional imaging sequences, (IV) adaptive spatial filtering can improve the fMRI data analysis, (V) clinical decisions should not be based on activation results from a single statistical threshold.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2009. , 73 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1121
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
URN: urn:nbn:se:liu:diva-18095ISBN: 978-91-7393-645-3 (print)OAI: oai:DiVA.org:liu-18095DiVA: diva2:214706
Public defence
2009-06-02, Majoren, Brigaden Restaurang & Konferens, Brigadgatan 17, 587 58 Linköping, Linköping, 09:15 (Swedish)
Opponent
Supervisors
Available from: 2009-05-06 Created: 2009-05-06 Last updated: 2014-10-02Bibliographically approved
List of papers
1. 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
2. Projection screen or video goggles as stimulus modality in functional magnetic resonance imaging
Open this publication in new window or tab >>Projection screen or video goggles as stimulus modality in functional magnetic resonance imaging
2005 (English)In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 23, no 5, 695-699 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to investigate the reliability of functional magnetic resonance imaging (fMRI) by using either a projection screen or video goggles as stimulus modality. A sequence of visual stimuli were presented to the same subject at different occasions. The sequence was optimized with a genetic algorithm. In five sessions the stimuli were presented using a projection screen viewed through a mirror in the head coil and in five sessions using video goggles. Failure to detect visual activation in the medial left hemisphere was observed in sessions using the projection screen as stimulus modality. Decreased thresholds for P values and cluster size resulted in activation outside the occipital lobe and did not significantly increase activated areas in this region. Results in this study indicate that presentation of fMRI tasks with visual routes is more reliable with direct input through video goggles than with the conventional use of projection screens. Failure to detect crucial visual areas has severe consequences for tumor surgery in the visual cortex. Inferior visual impression might also have negative consequences for cognitive tests with high demand on attention and perception.

Keyword
fMRI; Visual; Projection screen; Video goggles; Reliability
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-17992 (URN)10.1016/j.mri.2005.04.006 (DOI)16051046 (PubMedID)
Available from: 2009-04-30 Created: 2009-04-30 Last updated: 2017-12-13Bibliographically approved
3. Visual Grading of 2D and 3D fMRI compared to image based descriptive measures
Open this publication in new window or tab >>Visual Grading of 2D and 3D fMRI compared to image based descriptive measures
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2010 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 20, no 3, 714-724 p.Article in journal (Refereed) Published
Abstract [en]

A prerequisite for successful clinical use of functional Magnetic Resonance Imaging (fMRI) is the selection of an appropriate imaging sequence. In this paper, 2D and 3D fMRI sequences were compared using different image quality assessment methods. Descriptive image measures, such as activation volume and temporal signal-to-noise ratio (TSNR), were compared with results from Visual Grading Characteristics (VGC) analysis of the fMRI results. It was found that significant differences in activation volume and TSNR were not directly reflected by differences in VGC scores. The results suggest that better performance on descriptive image measures is not always an indicator of improved diagnostic quality of the fMRI results. In conclusion, in addition to descriptive image measures, it is important to include measures of diagnostic quality when comparing different fMRI data acquisition methods.

Place, publisher, year, edition, pages
Berlin / Heidelberg: Springer, 2010
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-17994 (URN)10.1007/s00330-009-1578-0 (DOI)000274544800023 ()19727748 (PubMedID)
Note

The original publication is available at www.springerlink.com: Mattias Ragnehed, Olof Dahlqvist Leinhard, Johan Pihlsgård, Staffan Wirell, Hannibal Sökjer, Patrik Fägerstam, Bo Jiang, Örjan Smedby, Maria Engström and Peter Lundberg, Visual Grading of 2D and 3D fMRI compared to image based descriptive measures, 2010, European Radiology, (20), 3, 714-724. http://dx.doi.org/10.1007/s00330-009-1578-0 Copyright: Springer Science Business Media http://www.springerlink.com/

Available from: 2009-04-30 Created: 2009-04-30 Last updated: 2017-12-13Bibliographically approved
4. Restricted Canonical Correlation Analysis in Functional MRI-Validation and a Novel Thresholding Technique
Open this publication in new window or tab >>Restricted Canonical Correlation Analysis in Functional MRI-Validation and a Novel Thresholding Technique
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2009 (English)In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 29, no 1, 146-154 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: To validate the performance of an analysis method for fMRI data based on restricted canonical correlation analysis (rCCA) and adaptive filtering, and to increase the usability of the method by introducing a new technique for significance estimation of rCCA maps.

Materials and Methods: Activation data from a language task and also a resting state fMRI data were collected from eight volunteers. Data was analyzed using both the rCCA method and the General Linear Model (GLM). A modified Receiver Operating Characteristic (ROC) method was used to evaluate the performance of the different analysis methods. The area under a fraction of the ROC curve was used as a measure of performance. On resting state data the fraction of voxels above certain significance thresholds were used to evaluate the significance estimation method.

Results: The rCCA method scored significantly higher on the area under the ROC curve than the GLM. The fraction of activated voxels determined by thresholding according to the introduced significance estimation technique showed good agreement with the thresholds selected.

Conclusion: The rCCA method is an effective analysis tool for fMRI data and its usability is increased with the introduced significance estimation method.

Keyword
fMRI, GLM, canonical correlation analysis, thresholding, significance
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-16411 (URN)10.1002/jmri.21494 (DOI)000262168200019 ()
Available from: 2009-01-23 Created: 2009-01-23 Last updated: 2017-12-14Bibliographically approved
5. Right-hemispheric brain activation correlates to language performance
Open this publication in new window or tab >>Right-hemispheric brain activation correlates to language performance
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2010 (English)In: NEUROIMAGE, ISSN 1053-8119, Vol. 49, no 4, 3481-3488 p.Article in journal (Refereed) Published
Abstract [en]

Language function in the right-hemispheric homologues of Brocas and Wernickes areas does not only correlate with left-handedness or pathology, but occurs naturally in right-handed healthy subjects as well. In the current study, two non-invasive methods of assessing language lateralization are correlated with behavioral results in order to link hemispheric dominance to language ability in healthy subjects. Functional magnetic resonance imaging (fMRI) together with a sentence-completion paradigm was used to determine region-specific lateralization indices in the left- and right-sided Brocas and Wernickes areas, the frontal temporal lobe, the anterior cingulate cortex and the parietal lobe. In addition, dichotic listening results were used to determine overall language lateralization and to strengthen conclusions by correlating with fMRI indices. Results showed that fMRI lateralization in the superior parietal, the posterior temporal, and the anterior cingulate cortices correlated to dichotic listening. A decreased right ear advantage (REA), which indicates less left- hemispheric dominance in language, correlated with higher performance in most administered language tasks, including reading, language ability, fluency, and non-word discrimination. Furthermore, right hemispheric involvement in the posterior temporal lobe and the homologue of Brocas area suggests better performance in behavioral language tasks. This strongly indicates a supportive role of the right-hemispheric counterparts of Brocas and Wernickes areas in language performance.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-53932 (URN)10.1016/j.neuroimage.2009.10.041 (DOI)000274064500059 ()
Note
Original Publication: Helene M van Ettinger-Veenstra, Mattias Ragnehed, Mathias Hällgren, Thomas Karlsson, Anne-Marie Landtblom, Peter Lundberg and Maria Engström, Right-hemispheric brain activation correlates to language performance, 2010, NEUROIMAGE, (49), 4, 3481-3488. http://dx.doi.org/10.1016/j.neuroimage.2009.10.041 Copyright: Elsevier Science B.V., Amsterdam http://www.elsevier.com/Available from: 2010-02-12 Created: 2010-02-12 Last updated: 2014-10-02

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Center for Medical Image Science and Visualization, CMIVRadiologyFaculty of Health SciencesDepartment of Radiology in LinköpingDepartment of Radiation Physics
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