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Open Access Publications from the University of California

Portable MRI and 129Xe Signal Amplification by Gas Extraction

  • Author(s): Graziani, Dominic Michael
  • Advisor(s): Pines, Alexander
  • et al.

Magnetic resonance has had an impact on nearly every branch of science from fundamental physics to neurobiology. Despite its pervasiveness, it remains a relatively inaccessible technique due to the costs associated with the powerful and highly precise instrumentation needed for sensitive detection. In this work, two techniques focused on improving the accessibility of magnetic resonance are presented. First, a low cost and portable volume imaging system is described with the unique ability to scan the homogeneous region of the magnetic field through a sample of interest. This system addresses the fundamental challenge of producing a compact imaging sensor while maintaining a sensitive region large enough to extract relevant information from the sample. The design of a suitable set of single-sided gradient coils compatible with the adjustable imaging system is presented first, followed by imaging results obtained with this apparatus. The second technique described in this work involves the use of xenon as a chemical sensor. Xenon's chemical shift sensitivity to its environment make it and ideal probe of its surroundings. Spin exchange optical pumping has made detection of dilute xenon solutions possible through hyperpolarization. However, optical pumping requires high power circularly polarized laser light, limiting applications of xenon from widespread use. An alternative method for signal amplification is presented, in which xenon is extracted from solution and compressed prior to detection. A description of the method is followed by several applications as well as a detailed description of the apparatus involved in the gas extraction and compression technique.

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