title: Change in the proton T(1) of fat and water in mixture.
abstract: This work describes observed changes in the proton T(1) relaxation time of both water and lipid when they are in relatively homogeneous mixtures. Results obtained from vegetable oil-water emulsions, pork kidney and lard mixtures, and excised samples of white and brown adipose tissues are presented to demonstrate this change in T(1) as a function of mixture fat fraction. As an initial proof of concept, a simpler acetone-water experiment was performed to take advantage of complete miscibility between acetone and water and both components' single chemical shift peaks. Single-voxel MR spectroscopy was used to measure the T(1) of predominant methylene spins in fat and the T(1) of water spins in each setup. In the vegetable oil-water emulsions, the T(1) of fat varied by as much as 3-fold when water was the dominant mixture component. The T(1) of pure lard increased by 170 msec (+37%) when it was blended with lean kidney tissue in a 16% fatty mixture. The fat T(1) of lipid-rich white adipose tissue was 312 msec. In contrast, the fat T(1) of leaner brown adipose tissue (fat fraction 53%) was 460 msec. A change in the water T(1) from that of pure water was also observed in the experiments.
authors.affiliation: Magnetic Resonance Engineering Laboratory, Signal and Image Processing Institute, Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089-2564, USA. houchunh@usc.edu
authors.forename: Houchun H
authors.initials: HH
authors.lastname: Hu
authors.forename: Krishna S
authors.initials: KS
authors.lastname: Nayak
mesh_terms: D000818:Animals; D045424:Complex Mixtures / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry; D005223:Fats / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D014867:Water / Q000737:chemistry*
chemical_list: D045424:Complex Mixtures; D004655:Emulsions; D005223:Fats; D011522:Protons; D014867:Water