A Multipurpose MRI phantom based on a reverse Micelle solution

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Title: A Multipurpose MRI phantom based on a reverse Micelle solution
Author: Roe, Jo
Abstract: Magnetic resonance imaging (MRI) phantoms are anthroprogenic objects used for system performance testing of an MR imager. Current phantoms used today contain aqueous solutions of paramagnetic salts. When imaged, these phantoms produce a standing wave artifact. The presence of this artifact make it difficult to distinguish between inhomogeneities in the B] transmit and receive field of an imaging coil and the imaging phantom. This thesis describes a reverse micelle (RM) solution and its applicability for use in an MR imaging phantom. The RM solution consists of three components: H20, which is surrounded by the surfactant, AOT, to form a droplet, which is suspended in the hydrocarbon, and decane. Volume fractions (<|>) of water and AOT from 0.50 to 0.9 0 were studied. The RM solution is easy to make up and is homogeneous. The RM solution was found to be phase-stable at temperatures ranging from 0 to 40C at certain <(> values. The dielectric constant of the RM solution was half the dielectric constant of H20. The resistivity of the RM solution was 5 times greater than an aqueous solution of 6 mM NiCl and 0. 1 54 mM NaCl. The diffusion coefficient of the H20 and AOT component increased as <j> increased. The diffusion coefficient of decane decreased as <|> increased. The viscosity of the RM solution increased as <|> increased. The viscosity of the RM solution is 35 times greater than the viscosity of H20. The RM solutions containing 0. 10, 0.25, and 0.50 mM Mn+2 in the aqueous phase produce overall T and T2 values similar to human tissue. The addition of either 3, 5, or 8 mM Ni+2 in the aqueous phase of the RM solution produces T and T2 values useful for system performance testing. The RM solution containing 8 mM Ni+2 in the aqueous phase displayed the least temperature dependent T] and T2of all six RM solutions studied. The RM solution phantom is effective in B1T and B]R field mapping. An image of the RM solution phantom displays minimal standing wave artifact and no skin-effect artifact. The spectrum of the RM solution phantom contains two peaks which correspond to the fat and H20 spectral peaks of human tissue. Consequently, the RM solution phantom could be used to test the fat saturation imaging sequence. Spectral T values of the H20 and decane component were measured. The individual T values differed from the overall T, values of the RM solution, thus, studying the effects of magnetization transfer between the three components could be possible. *Refer to content file for correct numerical representations
Record URI: http://hdl.handle.net/1850/13583
Date: 1996-05

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