TY  - 
  - Thesis/Dissertation
  - P. Cantillon-Murphy
  - 2008
  - June
  - On the Dynamics of Magnetic Fluids in Magnetic Resonance Imaging
  - Author
  - Published
  - 0
  - ()
  - Thesis in partial fulfillment of the requirements for the degree of Doctor of Philosophy at MIT
  - The hydrodynamics of magnetic fluids, often termed ferrofluids, has been an activearea of research since the mid 1960s. However, it is only in the past twenty yearsthat these fluids have begun to be used in magnetic resonance imaging (MRI) wherethey have found application as contrast agents, improving the contrast to noise ratioof the received MR intensity.The major goal of this work was to assess the feasibility of modulating the signalintensity in MRI in regions near superparamagnetic iron oxide contrast agents byapplying a rotating magnetic field. Analytical study and numerical simulations ofthe effects of such a rotating magnetic field are presented. Simulated variations influid magnetization are achieved by changing the frequency of the rotating magneticfield. A linearization of the equilibrium magnetization Langevin relation results in asmall signal magnetic susceptibility tensor that can be used to influence fluid flow.The feasibility of the approach under the real-life constraints of MR imaging areassessed. Also examined is the potential for coupling changes in magnetization dueto rotating fields with hyperthermia treatment of cancerous tissue.In addition to theoretical and simulated analysis, considerable experimental workwas undertaken at the MRI systems of the HST Athinoula A. Martinos Center forBiomedical Imaging at Massachusetts General Hospital, Charlestown, Massachusetts.This work evaluated the passive behavior of both commercial ferrofluids and MRIcontrast agents. The ability of MRI to serve as a highly accurate indicator of thefluid¿s physical and magnetic properties is shown. The thesis represents the firstinvestigation into the use of the hydrodynamic properties of magnetic fluid in thepresence of a rotating field as a mechanism for contrast in MRI. The results show thepossibility of varying MR image intensity under careful selection of field conditions.
  - Cambridge, Massachusetts
  - Massachusetts Institute of Technology
  - http://dspace.mit.edu/handle/1721.1/44403
DA  - 2008/06
ER  - 

@thesis{V73897520,
   = {Thesis/Dissertation},
   = {P. Cantillon-Murphy },
   = {2008},
   = {June},
   = {On the Dynamics of Magnetic Fluids in Magnetic Resonance Imaging},
   = {Author},
   = {Published},
   = {0},
   = {()},
   = {Thesis in partial fulfillment of the requirements for the degree of Doctor of Philosophy at MIT},
   = {{The hydrodynamics of magnetic fluids, often termed ferrofluids, has been an activearea of research since the mid 1960s. However, it is only in the past twenty yearsthat these fluids have begun to be used in magnetic resonance imaging (MRI) wherethey have found application as contrast agents, improving the contrast to noise ratioof the received MR intensity.The major goal of this work was to assess the feasibility of modulating the signalintensity in MRI in regions near superparamagnetic iron oxide contrast agents byapplying a rotating magnetic field. Analytical study and numerical simulations ofthe effects of such a rotating magnetic field are presented. Simulated variations influid magnetization are achieved by changing the frequency of the rotating magneticfield. A linearization of the equilibrium magnetization Langevin relation results in asmall signal magnetic susceptibility tensor that can be used to influence fluid flow.The feasibility of the approach under the real-life constraints of MR imaging areassessed. Also examined is the potential for coupling changes in magnetization dueto rotating fields with hyperthermia treatment of cancerous tissue.In addition to theoretical and simulated analysis, considerable experimental workwas undertaken at the MRI systems of the HST Athinoula A. Martinos Center forBiomedical Imaging at Massachusetts General Hospital, Charlestown, Massachusetts.This work evaluated the passive behavior of both commercial ferrofluids and MRIcontrast agents. The ability of MRI to serve as a highly accurate indicator of thefluid¿s physical and magnetic properties is shown. The thesis represents the firstinvestigation into the use of the hydrodynamic properties of magnetic fluid in thepresence of a rotating field as a mechanism for contrast in MRI. The results show thepossibility of varying MR image intensity under careful selection of field conditions.}},
   = {Cambridge, Massachusetts},
   = {{Massachusetts Institute of Technology}},
   = {http://dspace.mit.edu/handle/1721.1/44403},
  source = {IRIS}
}