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Dissertation
Current-sensitive magnetic resonance imaging technique
Doctor of Philosophy (Ph.D.), Drexel University
Aug 2002
DOI:
https://doi.org/10.17918/00009230
Abstract
This work investigates the theory and ascertains an experimental feasibility of the current-sensitive magnetic resonance imaging technique, a method to study various human physiological functions. The method's physical principles are based on non-invasive magnetometric detection and measurement of weak magnetic fields originated from electrical currents, which could be of an electrochemical origin. Such current-induced magnetic fields manifest themselves through an interference with nuclear magnetism. The infinitesimal deviations of precession rates produced by these interactions affect the generated magnetic resonance signal and result in specific imaging artifacts which can be employed as endogenous markers of the original currents. The following original theoretical results were obtained: (1) the relations between the amplitude of the original electrical currents and related magnetic resonance signal; (2) the expressions for the sensitivity limit given as a function of the most essential parameters and characteristics of the imaging system, such as echo time, reception band-width; (3) the description of the technique sensitivity dependence on system's static magnetic field strength. These results led to predictions of the system- and imaging protocol-specific lowest detectable currents. The experimental trials with various imaging protocols confirmed the important role of the echo time. To achieve the utmost sensitivity, in a novel approach the "spiral" imaging protocols specifically tailored to target lower electrical currents were employed. Another significant result was attained in comparative experiments on imaging systems with different static magnetic field strengths. It was shown for the first time, both theoretically and experimentally, that the higher field strength decreases the detection sensitivity, and that higher amplification gains of the detection electronics can be used to compensate for such sensitivity losses. Overall, this work establishes the basis of the proposed current-sensitive magnetic resonance imaging technique and contributes its design, theoretical and feasibility considerations to the knowledge base of the methods aimed towards non-invasive detection and assessment of human neuronal functions. It is hoped that the proposed methodology will have an eventual effect in the field of neuroscience in general and in the study of human neuronal functions in particular.
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Details
- Title
- Current-sensitive magnetic resonance imaging technique
- Creators
- Alexander B. Pinus
- Contributors
- Scott H. Faro (Advisor) - Drexel University, Drexel University (1970-)Feroze Babu Mohamed (Advisor) - Drexel University, Drexel University (1970-)Oleh John Tretiak (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xiv, 216 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Engineering (1970-2026); Drexel University
- Other Identifier
- 991021888988804721