This thesis describes an implementation of the so-called"zero-field MRI" (ZFMRI) pulse sequence, which allows for imaging in an arbitrarily low B<sub>0</sub> field. The ZFMRI sequence created an effective unidirectional gradient field by using a train of pi pulses to average out the concomitant gradient components during encoding. The signals were acquired using a low-transition temperature dc Superconducting QUantum Interference Device (low-Tc dc SQUID) coupled to a first-order axial gradiometer. The experiments were carried out in a liquid helium dewar which was magnetically shielded with a single-layer mu-metal can around the outside and a superconducting Pb can contained within the helium …
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This thesis describes an implementation of the so-called"zero-field MRI" (ZFMRI) pulse sequence, which allows for imaging in an arbitrarily low B<sub>0</sub> field. The ZFMRI sequence created an effective unidirectional gradient field by using a train of pi pulses to average out the concomitant gradient components during encoding. The signals were acquired using a low-transition temperature dc Superconducting QUantum Interference Device (low-Tc dc SQUID) coupled to a first-order axial gradiometer. The experiments were carried out in a liquid helium dewar which was magnetically shielded with a single-layer mu-metal can around the outside and a superconducting Pb can contained within the helium space. We increased the filling factor of the custom-made, double-walled Pyrex insert by placing the liquid alcohol sample, at a temperature of approximately -50 degrees C, at the center of one loop of the superconducting gradiometer, which was immersed in the helium bath.
Related Information: Designation of Academic Dissertation: Doctoral thesis; Academic Degree: Ph.D.; Name of Academic Institution: University of California, Berkeley; Location of Academic Institution: Berkeley, CA
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Kelso, Nathan Dean.SQUID-Detected MRI in the Limit of Zero Static Field,
thesis or dissertation,
December 14, 2009;
United States.
(https://digital.library.unt.edu/ark:/67531/metadc1012820/:
accessed June 7, 2024),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.
