On the strong field dependence and nonlinear response to gadolinium contrast agent of proton transverse relaxation rates in dairy cream |
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Authors: | Mulkern Robert V Hung Yin P Ababneh Zaid Maier Stephan E Packard Alan B Uluer Mehmet C Kacher Daniel F Gambarota Giulio Voss Stephan |
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Institution: | Department of Radiology, Children's Hospital, Boston, MA 02468, USA. rmulkern@yahoo.com |
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Abstract: | Dairy cream, as a suspension of lipid droplets in water, is a potentially useful magnetic resonance imaging (MRI) phantom material and an interesting material for studying fundamental relaxation mechanisms. Here we report a strong increase in the transverse relaxation rates with field strength for both the water and lipid protons in dairy cream. Also, studies at 4.7 T reveal a nonlinear response of transverse relaxation rates with increasing concentration of a common gadolinium (Gd)-based contrast agent, including an initial decrease of water relaxation rates as measured with Hahn spin echoes at the lower Gd concentrations. The results are treated within the framework of a model in which the magnetic susceptibility difference between the lipid droplets and the aqueous phase plays the prominent role for transverse relaxation. Second-order polynomial fits of the water proton transverse relaxation rate dependence on field strength and on Gd concentration at 4.7 T provided experimental parameters from which model parameters are extracted and compared with expectations available from the literature. |
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