Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(multiexponential T2). Showing records 1 – 3 of 3 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


Vanderbilt University

1. West, Kathryn Louise. Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains.

Degree: PhD, Biomedical Engineering, 2016, Vanderbilt University

Advanced neuroimaging techniques provide the possibility to non-invasively understand and monitor white matter during development and disease. While data from quantitative MRI techniques, such as multiexponential T2 (MET2) and quantitative magnetization transfer (qMT), correlate with myelin content, neither provide an absolute measure of the myelin volume fraction (MVF). Additionally, in preclinical studies, despite time-intensity and small tissue samples, histology remains the gold standard for quantitatively assessing changes in myelin content and white matter microstructural properties, such as myelin thickness and the g-ratio (ratio of axon radius to myelinated fiber radius). Therefore, the work in this dissertation first established and validated methods for MVF imaging from MET2 and qMT against quantitative electron microscopy. We show strong agreement in adult, control mice along with three mouse models of white matter disease. Next, we applied MVF imaging in mice during normal development and observe good agreement between MET2 and qMT and with expected myelin development. To further investigate specific changes in myelin microstructure, recent methods proposed measuring the g-ratio from MRI (gMRI). We revised the model and displayed with quantitative histology that gMRI provides an axon-area-weighted g-ratio. Calculating gMRI requires an accurate measure of MVF; thus, we utilize our MVF imaging techniques to measure gMRI in mouse brain and detect changes in g-ratio with disease in agreement with quantitative histology. In short, we develop and validate measures of MVF and g-ratio from MRI which have the potential to non-invasively provide more specific and thorough assessment of white matter not obtainable with currently used methods. Advisors/Committee Members: Adam W. Anderson (committee member), Kevin C. Ess (committee member), Daniel F. Gochberg (committee member), John C. Gore (committee member), Mark D. Does (Committee Chair).

Subjects/Keywords: magnetization transfer; multiexponential T2; myelin; MRI; neuroimaging; histology; g-ratio

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

West, K. L. (2016). Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14525

Chicago Manual of Style (16th Edition):

West, Kathryn Louise. “Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains.” 2016. Doctoral Dissertation, Vanderbilt University. Accessed January 16, 2021. http://hdl.handle.net/1803/14525.

MLA Handbook (7th Edition):

West, Kathryn Louise. “Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains.” 2016. Web. 16 Jan 2021.

Vancouver:

West KL. Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains. [Internet] [Doctoral dissertation]. Vanderbilt University; 2016. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1803/14525.

Council of Science Editors:

West KL. Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains. [Doctoral Dissertation]. Vanderbilt University; 2016. Available from: http://hdl.handle.net/1803/14525


Université Paris-Sud – Paris XI

2. Araujo, Ericky Caldas de Almeida. Adaptation of Proof of Concepts Into Quantitative NMR Methods : Clinical Application for the Characterization of Alterations Observed in the Skeletal Muscle Tissue in Neuromuscular Disorders : Des preuves de concepts à la mise en œuvre de méthodes de RMN quantitative : application clinique à la caractérisation des altérations du muscle strié squelettique dans les pathologies neuro-musculaires.

Degree: Docteur es, Physique, 2014, Université Paris-Sud – Paris XI

Actuellement, des méthodes quantitatives de résonance magnétique nucléaire (RMN) offrent des biomarqueurs qui permettent la réalisation d’études longitudinales pour le suivi de l’évolution des maladies neuromusculaires et des essais thérapeutiques de manière non-invasive. A la différence de la dégénérescence graisseuse, les processus d’inflammation/œdème/nécrose et fibrose sont des signes d’activité des maladies et leurs quantifications constitueraient ainsi de biomarqueurs parfaitement adaptés pour le suivi thérapeutique. Ce travail de thèse a consisté à mettre en place des méthodologies quantitatives plus précises et adaptées à l’étude clinique du muscle pour : (i) détecter et quantifier des sites d’activité de maladies par la cartographie T2 de l’eau ; (ii) identifier les différents processus pathophysiologiques qui sont à l’origine des altérations du T2 ; et (iii) détecter et quantifier la fibrose musculaire. Nous avons implémenté deux méthodes pour la quantification du T2 de l’eau dans le muscle. La première est basée sur une séquence d’écho de spin du type CPMG, où les signaux provenant des protons des lipides et de l’eau sont acquis simultanément et séparés à postériori par un traitement tri-exponentiel qui exploite la différence entre les T2 qui caractérisent les signaux de l’eau et de la graisse. La deuxième technique est basée sur une séquence de « partially spoiled steady state free precession (pSSFP) ». Différemment de la première technique qui nécessite un traitement assez élaboré sur des images acquises à 17 temps d’écho différents, dans la pSSFP la cartographie T2 est extraite à partir de deux séries de données 3D. L’acquisition 3D est compatible avec des techniques de sélection spectrale de l’eau, ce qui évite la contamination par les signaux des lipides. Les deux méthodes ont été validées expérimentalement chez des malades et des sujets sains et ont démontré leur capacité à détecter et quantifier des sites d’activité de maladies. Ces deux travaux font l’objet de deux publications dans des journaux scientifiques internationaux : Azzabou, de Sousa, Araujo, & Carlier, 2014. Journal of Magnetic Resonance Imaging. DOI 10.1002/jmri.24613 (in press); et de Sousa, Vignaud, Araujo, & Carlier . 2012. Magnetic Resonance in Medicine. 67:1379-1390. Malgré le fait de permettre la détection des sites d’activité de maladies, la mesure mono-exponentielle du T2 de l’eau par imagerie reste non-spécifique vis-à-vis des processus physiologiques à l’origine de l’augmentation du T2. Il est connu que la relaxation T2 du muscle squelettique n’est pas mono-exponentielle. Cela est interprété comme une conséquence de la compartimentation anatomique de l’eau tissulaire. Nous avons mis au point une méthode pour l’acquisition localisée de données CPMG. Cette technique permet l’acquisition des données dans des conditions nécessaires pour la réalisation de traitements multi-exponentiels précis. Ce travail nous a permis d’établir un modèle de compartimentation qui explique parfaitement la relaxation T2 dans le muscle. Il a fait… Advisors/Committee Members: Carlier, Pierre (thesis director).

Subjects/Keywords: Résonance magnétique nucléaire (RMN); Imagerie quantitative par résonance magnétique nucléaire (IqRMN); Relaxométrie T2; Muscle squelettique; Cartographie T2; Relaxation T2 multi-exponentielle; Temps d’écho ultra-court; Nuclear magnetic resonance (NMR); Quantitative nuclear magnetic resonance imaging (qNMRI); T2-relaxometry; Skeletal muscle (SKM); T2-mapping; Multiexponential T2-relaxation; Ultrashort time-to-echo (UTE)

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Araujo, E. C. d. A. (2014). Adaptation of Proof of Concepts Into Quantitative NMR Methods : Clinical Application for the Characterization of Alterations Observed in the Skeletal Muscle Tissue in Neuromuscular Disorders : Des preuves de concepts à la mise en œuvre de méthodes de RMN quantitative : application clinique à la caractérisation des altérations du muscle strié squelettique dans les pathologies neuro-musculaires. (Doctoral Dissertation). Université Paris-Sud – Paris XI. Retrieved from http://www.theses.fr/2014PA112075

Chicago Manual of Style (16th Edition):

Araujo, Ericky Caldas de Almeida. “Adaptation of Proof of Concepts Into Quantitative NMR Methods : Clinical Application for the Characterization of Alterations Observed in the Skeletal Muscle Tissue in Neuromuscular Disorders : Des preuves de concepts à la mise en œuvre de méthodes de RMN quantitative : application clinique à la caractérisation des altérations du muscle strié squelettique dans les pathologies neuro-musculaires.” 2014. Doctoral Dissertation, Université Paris-Sud – Paris XI. Accessed January 16, 2021. http://www.theses.fr/2014PA112075.

MLA Handbook (7th Edition):

Araujo, Ericky Caldas de Almeida. “Adaptation of Proof of Concepts Into Quantitative NMR Methods : Clinical Application for the Characterization of Alterations Observed in the Skeletal Muscle Tissue in Neuromuscular Disorders : Des preuves de concepts à la mise en œuvre de méthodes de RMN quantitative : application clinique à la caractérisation des altérations du muscle strié squelettique dans les pathologies neuro-musculaires.” 2014. Web. 16 Jan 2021.

Vancouver:

Araujo ECdA. Adaptation of Proof of Concepts Into Quantitative NMR Methods : Clinical Application for the Characterization of Alterations Observed in the Skeletal Muscle Tissue in Neuromuscular Disorders : Des preuves de concepts à la mise en œuvre de méthodes de RMN quantitative : application clinique à la caractérisation des altérations du muscle strié squelettique dans les pathologies neuro-musculaires. [Internet] [Doctoral dissertation]. Université Paris-Sud – Paris XI; 2014. [cited 2021 Jan 16]. Available from: http://www.theses.fr/2014PA112075.

Council of Science Editors:

Araujo ECdA. Adaptation of Proof of Concepts Into Quantitative NMR Methods : Clinical Application for the Characterization of Alterations Observed in the Skeletal Muscle Tissue in Neuromuscular Disorders : Des preuves de concepts à la mise en œuvre de méthodes de RMN quantitative : application clinique à la caractérisation des altérations du muscle strié squelettique dans les pathologies neuro-musculaires. [Doctoral Dissertation]. Université Paris-Sud – Paris XI; 2014. Available from: http://www.theses.fr/2014PA112075


Vanderbilt University

3. Dula, Adrienne Nicole. Micro-anatomical characterization of central white matter using magnetic resonance imaging.

Degree: PhD, Biomedical Engineering, 2008, Vanderbilt University

Most magnetic resonance imaging techniques offer tissue contrast but provide limited information regarding the variation of the magnetic resonance signal that exists on a smaller scale. The magnetic resonance signal arising from a heterogeneous tissue, such as spinal cord white matter, is the sum of signals from each tissue compartment within the imaging voxel. Analysis of this signal can better characterize the micro-anatomical heterogeneity tissue, white matter in particular. Many questions remain with regard to the compartmental contributions for the various types of magnetic resonance imaging (MRI) contrast. This project utilizes a variety of in vitro studies as well as simulations to better characterize the contribution of different water compartments to conventional MRI methods. Such an understanding of the complex combination of the various relaxation and exchange properties is important in developing an anatomical basis for interpreting magnetization transfer and T2 weighted images, particularly with respect to myelination. Advisors/Committee Members: Bill Valentine (committee member), Adam Anderson (committee member), Dan Gochberg (committee member), John Gore (committee member), Dr. Mark Does (Committee Chair).

Subjects/Keywords: quantitative magnetization transfer; multiexponential T2; Spinal cord  – Magnetic resonance imaging; myelin; Myelination

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Dula, A. N. (2008). Micro-anatomical characterization of central white matter using magnetic resonance imaging. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/12177

Chicago Manual of Style (16th Edition):

Dula, Adrienne Nicole. “Micro-anatomical characterization of central white matter using magnetic resonance imaging.” 2008. Doctoral Dissertation, Vanderbilt University. Accessed January 16, 2021. http://hdl.handle.net/1803/12177.

MLA Handbook (7th Edition):

Dula, Adrienne Nicole. “Micro-anatomical characterization of central white matter using magnetic resonance imaging.” 2008. Web. 16 Jan 2021.

Vancouver:

Dula AN. Micro-anatomical characterization of central white matter using magnetic resonance imaging. [Internet] [Doctoral dissertation]. Vanderbilt University; 2008. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1803/12177.

Council of Science Editors:

Dula AN. Micro-anatomical characterization of central white matter using magnetic resonance imaging. [Doctoral Dissertation]. Vanderbilt University; 2008. Available from: http://hdl.handle.net/1803/12177

.