Aqueous urea as a model system for bi-exponential relaxation.

MAGMA

Department of Biomedical Engineering, Vanderbilt University School of Engineering, Nashville, TN 37232-2310, USA.

Published: February 2007

Object: To evaluate the utility of aqueous urea, doped inner- and outer-sphere relaxation agents, as an adjustable two-component model system.

Materials And Methods: T2 was measured from 12 molal urea mixtures at pH 7.0 with varying amounts of the MnCl2 and FeO(1.44) (Feridex, Berlex Inc, Montville, NJ).

Results: Bi-exponential relaxation was observed, with rates that were bilinearly related to [MnCl2] and [FeO(1.44)]. FeO(1.44) had comparable relaxivities on both urea and water, while MnCl2 relaxivity was > 15x larger for water than for urea.

Conclusion: Aqueous urea, doped with inner- and outer-sphere contrast agents, is a two-compartment model system, which can be exhibit a wide range of different T2s and signal fractions.

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http://dx.doi.org/10.1007/s10334-006-0064-9DOI Listing

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