rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    non sort: A
    title: study of array SNR and coupling as a function of the input impedance of preamplifier
  name:
    name part: Shah, Bijay Kamleshbhai.
    role:
      role term: creator
  name:
    name part: Wright, Steven M.
    role:
      role term: thesis advisor.
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: txu
    date issued: 2010
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: electronic
    form: remote
    extent: 1 online resource.
  abstract: Much of the current research in magnetic resonance engineering focuses on reducing the acquisition time for obtaining an image while simultaneously maximizing the Signal to Noise ratio (SNR) of the image. It is known that improvement in imaging time or resolution is obtained at the cost of SNR. Therefore wherever possible, RF coil engineers design the coil in such a manner so as to maximize SNR for that coil design. In one such design consideration, most coil designers prefer placing low impedance preamplifiers near the coil. The further the pre-amplifiers are from the coil, the greater will be the signal loss due to transmission and higher will be its input impedance as perceived at the coil which would degrade inter-coil isolation. Owing to the current trend of using increasing number of receiver channels (32, 64 or 128) for parallel imaging, placing the preamplifiers near the coil would greatly complicate the coil construction. The primary objective of this research was to find the relation between SNR and referred preamp impedance and whether preamps need to be placed on the coil, or if they can be placed outside the magnet at the end of a transmission line which would simplify the construction of large count array. In addition, SNR was studied as a function of coil design parameters - coil loading, array coil separation, and system frequency. Both theoretical and experimental methods were used to undertake this investigation. A popular electromagnetic modeling technique, finite difference time domain (FDTD), was used to model SNR in arrays of two 3 inch loop coils at 3T and 1.5T. Results were also verified through bench measurement at 3T and 1.5T and by evaluating SNR. To verify the robustness of our results and to assess the possibility of using low cost standard 50 ohm preamps, we carried out additional bench measurements at 4.7T. Results demonstrated that preamplifier placement is critical at low field strength. At higher field strength, SNR degradation due …
  note: by Bijay Kamleshbhai Shah.
  note: "Major Subject: Biomedical Engineering"
  note: Title from author supplied metadata (automated record created 2010-03-12 12:08:51).
  note: Electronic resource.
  note: Master of Science Texas A&M University 2007 http://hdl.handle.net/1969.1/ETD-TAMU-2441
  note: Includes bibliographical references.
  note: Text (Thesis)
  subject:
    topic: Major biomedical engineering
  subject:
    topic: RF Coils
  subject:
    topic: Signal to Noise Ratio
  subject:
    topic: Preamplifier
  subject:
    topic: MRI
  subject:
    topic: Coupling
  identifier: http://hdl.handle.net/1969.1/ETD-TAMU-2441
  record info:
    record content source: TXA
    record creation date: 100427
    record change date: 20151201120129.0
    record identifier: in00002571185