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    Magnetic Resonance Spectroscopy as part of a comprehensive neuroimaging assessment tool

    Sanaei Nezhad, Faezeh

    [Thesis]. Manchester, UK: The University of Manchester; 2018.

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    Abstract

    Magnetic resonance spectroscopy (MRS) allows the non-invasive measurement of selected biological compounds in vivo. Despite MRS proven potential it is not yet a routine clinical tool operated by clinicians. This is mainly due to the complex procedure of MRS acquisition, lack of standardisation in both acquisition and analysis protocols along with lack of a standard quality control. This thesis intended to address these issues with the focus on four metabolites glutathione, glutamate, glutamine and GABA using MEGA-PRESS pulse sequence. Recommendations on acquisition and spectra analysis is made for the MRS protocol MEGA-PRESS aiming to detect glutathione in vivo. This is based on an investigation of glutathione acquisition in vivo and in vitro and was aimed to answer the question: can glutathione be measured reliably using conventional pulse sequence PRESS or does it require editing? The results showed strong evidence of using editing in order to have a reliable glutathione concentration measurement. An analysis along with a quality control method is also presented to enable the extraction of glutamate and glutamine from a GABA-optimised MEGA-PRESS pulse sequence. This enables simultaneous measurements of GABA, glutamate and glutamine in a single acquisition. A criterion of NAA linewidth <8 Hz and Glx CRLB <16% were defined as optimum features in the GABA-edited spectrum for a reliable glutamate and glutamine quantification. Finally, due to the increasing interest in functional MRS of GABA using MEGA- PRESS an investigation on the feasibility of measuring GABA in a functional-MRS setting was performed with recommendations on study designs and subject size. Power calculations suggest that detecting a 40% change in GABA using a 4’30” acquisition requires 9-93 subjects per group in a between-group study design and 13- 68 participants in a within-session design, depending on the region of interest. This thesis is set out in the Journal format thesis. Three introductory chapters, with each experimental study presented as a chapter and a final chapter that summarises and discusses the work. Results in this thesis provide a basis for a standard and reliable MRS pipeline to reliably measure glutathione, glutamate, glutamine and GABA using MEGA-PRESS pulse sequence at 3 Tesla.

    Bibliographic metadata

    Type of resource:
    Content type:
    Form of thesis:
    Type of submission:
    Degree type:
    Doctor of Philosophy
    Degree programme:
    PhD Medicine 3yr IIDS
    Publication date:
    Location:
    Manchester, UK
    Total pages:
    149
    Abstract:
    Magnetic resonance spectroscopy (MRS) allows the non-invasive measurement of selected biological compounds in vivo. Despite MRS proven potential it is not yet a routine clinical tool operated by clinicians. This is mainly due to the complex procedure of MRS acquisition, lack of standardisation in both acquisition and analysis protocols along with lack of a standard quality control. This thesis intended to address these issues with the focus on four metabolites glutathione, glutamate, glutamine and GABA using MEGA-PRESS pulse sequence. Recommendations on acquisition and spectra analysis is made for the MRS protocol MEGA-PRESS aiming to detect glutathione in vivo. This is based on an investigation of glutathione acquisition in vivo and in vitro and was aimed to answer the question: can glutathione be measured reliably using conventional pulse sequence PRESS or does it require editing? The results showed strong evidence of using editing in order to have a reliable glutathione concentration measurement. An analysis along with a quality control method is also presented to enable the extraction of glutamate and glutamine from a GABA-optimised MEGA-PRESS pulse sequence. This enables simultaneous measurements of GABA, glutamate and glutamine in a single acquisition. A criterion of NAA linewidth <8 Hz and Glx CRLB <16% were defined as optimum features in the GABA-edited spectrum for a reliable glutamate and glutamine quantification. Finally, due to the increasing interest in functional MRS of GABA using MEGA- PRESS an investigation on the feasibility of measuring GABA in a functional-MRS setting was performed with recommendations on study designs and subject size. Power calculations suggest that detecting a 40% change in GABA using a 4’30” acquisition requires 9-93 subjects per group in a between-group study design and 13- 68 participants in a within-session design, depending on the region of interest. This thesis is set out in the Journal format thesis. Three introductory chapters, with each experimental study presented as a chapter and a final chapter that summarises and discusses the work. Results in this thesis provide a basis for a standard and reliable MRS pipeline to reliably measure glutathione, glutamate, glutamine and GABA using MEGA-PRESS pulse sequence at 3 Tesla.
    Thesis main supervisor(s):
    Thesis co-supervisor(s):
    Language:
    en

    Institutional metadata

    University researcher(s):
    Academic department(s):

    Record metadata

    Manchester eScholar ID:
    uk-ac-man-scw:313312
    Created by:
    Sanaei Nezhad, Faezeh
    Created:
    5th February, 2018, 11:49:34
    Last modified by:
    Sanaei Nezhad, Faezeh
    Last modified:
    2nd March, 2018, 10:30:14

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