In vivo measurement of absolute metabolite concentrations with quantitative magnetic resonance imaging and spectroscopy
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Graf, Carina
issued: 2019-08-21T16:13:56Z
issued: 2019
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Magnetic resonance spectroscopy (MRS) measures relative signals arising from spins on different metabolites, e.g. N-Acetyl aspartate (NAA). To improve the interpretability of changes caused by disease, it is optimal to convert these relative signals to absolute concentrations e.g. by referencing it to the MR signal of water. Segmentation of high-resolution qualitative magnetic resonance images (MRI) is an accessible and easy-to-use method to estimate the properties of tissue water in the spectroscopic volume of interest (VOI), including water content, [H₂O], and relaxation properties (T₁, T₂) with pre-determined literature values. However, these tissue properties can change in disease and with age. Therefore, we proposed the use of a quantitative MRI approach to reference metabolite concentrations by measuring subject-specific T₁ and T₂ relaxation as well as water content maps. The approach was first validated by measuring a range of biologically relevant water contents and metabolite concentrations in vitro. [H₂O] was overestimated by 4.8% on average, while NAA concentrations were underestimated by 9.9%. In a study of ten healthy controls comparing the traditional segmentation quantification with the novel quantitative MRI method, we observed larger variabilities for subject-specific water properties, which did not propagate to the variability of the absolute metabolite concentrations of the neurochemicals (p > 0.37). Metabolite concentrations were lower with the quantitative MRI approach by -5.4% (p=0.002) in a white matter volume of interest (VOI) and -2.4% (p=0.002) in a grey matter VOI compared to the segmentation-based quantification. The quantitative MRI method for calculating absolute metabolite concentrations in MRS showed promising results, offering a potential alternative for the currently widely used segmentation approach.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/71365
note: IN VIVO MEASUREMENT OF ABSOLUTE METABOLITE CONCENTRATIONS WITH QUANTITATIVE MAGNETIC RESONANCE IMAGING AND SPECTROSCOPY by Carina Graf B.Sc., Technische Universität Dortmund, 2016 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Physics) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) August 2019 © Carina Graf, 2019 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled: In vivo measurement of absolute metabolite concentrations with quantitative magnetic resonance imaging and spectroscopy submitted by Carina Graf in partial fulfilment of the requirements for the degree of Master of Science in Physics Examining Committee: Dr. Cornelia Laule Supervisor Dr. Erin L MacMillan Supervisory Committee Member iii Abstract Magnetic resonance spectroscopy (MRS) measures relative signals arising from spins on different metabolites, e.g. N-Acetyl aspartate (NAA). To improve the interpretability of changes caused by disease, it is optimal to convert these relative signals to absolute concentrations e.g. by referencing it to the MR signal of water. Segmentation of high-resolution qualitative magnetic resonance images (MRI) is an accessible and easy-to-use method to estimate the properties of tissue water in the spectroscopic volume of interest (VOI), including water content, [H2O], and relaxation properties (T1, T2) with pre-determined literature values. However, these tissue properties can change in disease and with age. Therefore, we proposed the use of a quantitative MRI approach to reference metabolite concentrations by measuring subject-specific T1 and T2 relaxation as well as water content maps. The approach was first validated by measuring a range of biologically relevant water contents and metabolite concentrations in vitro. [H2O] was overestimated by 4.8% on average, whi…
has type: Thesis/Dissertation
date issued: 2019-09
is shown at: 10.14288/1.0380533
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/71365