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Dissertation-JVarghese_Aug19,2016.pdf (4.95 MB)

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A Magnetic Resonance Imaging Method to Non-Invasively Measure Blood Oxygen Saturation

Varghese, Juliet Jaison
http://orcid.org/0000-0003-2882-2893
http://rave.ohiolink.edu/etdc/view?acc_num=osu1471622211

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Biomedical Engineering.
Cardiovascular disease impacts systemic and organ-specific oxygen supply and extraction. An accurate measurement of blood oxygen saturation (O2 sat) in the heart and major blood vessels is therefore an important biomarker in the clinical evaluation and characterization of cardiovascular disease. Currently, the standard method of obtaining this measurement is by invasive catheterization, which carries significant risks. Although efforts have been made to develop surrogate markers and non-invasive measurement techniques, they cannot replace the clinical significance of a measurement of mixed venous O2 sat in the heart. Therefore, the focus of this research was to develop a truly non-invasive imaging technique to estimate oxygen saturation in the heart. Magnetic resonance (MR) methods to determine blood oxygen saturation have been proposed, tried, and tested for the past twenty-five years. Numerous assumptions are involved in the determination of blood O2 sat from MR relaxation times. As such, transverse relaxation (T2) based MR oximetry techniques rely on technique-specific and patient-specific in vitro calibration in order to reduce the variability arising from these assumptions. However, these impractical requirements have hindered the widespread application of these techniques, and have prevented them from gaining clinical acceptance. Cardiovascular physiology and pathophysiology, and MR imaging physics was reviewed to identify the clinical need as well as the potential engineering pathways to develop a reliable, clinically useful solution to non-invasively estimate blood O2 sat. The result is a technique that augments the diagnostic potential of the MR evaluation of cardiovascular diseases such as congenital heart disease, heart failure and pulmonary hypertension. The novel concept presented in this research work obviates the need for an in vitro calibration process required by previously proposed T2 based MR oximetry methods, and provides a more reliable, patient specific, estimation of blood oxygen saturation by MR imaging. This unique solution exploits the dependence of blood T2 on the inter-echo spacing (t180) of a spin-echo pulse train, in order to acquire a range of effective T2 values of blood as a function of t180. This generates sufficient data to perform a reliable fit of the proton exchange model which describes the relationship between blood T2 and oxygen saturation. The work described in this dissertation involving the proposed MR technique – preliminary implementation in a cohort of healthy volunteers at clinically used field strengths of 1.5T and 3T, evaluation across a range of oxygen saturation levels in a porcine model with a progressive hypoxemia experiment, and comparison in a cohort of cardiovascular patients against gold standard measurement of invasive right catheterization - serve to establish proof-of-concept and validity, and explore potential clinical applications of the proposed technique.
Orlando Simonetti, PhD (Advisor)
Subha Raman, MD, MSEE (Committee Member)
Jun Liu, PhD (Committee Member)
Rizwan Ahmad, PhD (Committee Member)
Ning Jin, PhD (Committee Member)
187 p.
Biomedical Engineering
magnetic resonance imaging; blood oxygen saturation; MR oximetry; cardiovascular MRI; congenital heart disease; heart failure; pulmonary hypertension

Recommended Citations

Citations

  • Varghese, J. J. (2016). A Magnetic Resonance Imaging Method to Non-Invasively Measure Blood Oxygen Saturation [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471622211

    APA Style (7th edition)

  • Varghese, Juliet. A Magnetic Resonance Imaging Method to Non-Invasively Measure Blood Oxygen Saturation. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1471622211.

    MLA Style (8th edition)

  • Varghese, Juliet. "A Magnetic Resonance Imaging Method to Non-Invasively Measure Blood Oxygen Saturation." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471622211

    Chicago Manual of Style (17th edition)

osu1471622211
566
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This open access ETD is published by The Ohio State University and OhioLINK.