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Oxygen-17 and Proton Mr Microscopy in Materials Analysis

  • G.D. Mateescu (a1), R.A. Kinsey (a2) and G.M. Yvars (a1)

Abstract

Preliminary results of two applications of 17O/lH NMR microimaging (MRμI) are described. In the first case, it is shown that oxygen-17 MRμI presents a unique advantage in situations where a strong proton background hinders the analysis of water ingress in polymeric materials. This is illustrated with 17O-enriched water diffusion into an agar gel from a central well. While proton imaging cannot readily distinguish between exogenous and endogenous water, 17O imaging makes a clear differentiation, due to the fact that the natural abundance gel has virtually no 17O background. In the second case, proton MRμI was used to analyze the structure and performance of commercial time-release pellets (ProMacR) containing an active ingredient (surfactant) dispersed into an inert matrix. This was done after leaching the detergent with natural abundance water or after drying the leached sample and refilling the pores with water. Pores ranging in size from 25 to 325 μm diameter are clearly visualized. The 1H images have been quantitated with commercial image analysis software in terms of the total porosity and the individual pore characteristics. Two types of water can be separately imaged: “bound” water with restricted mobility (interacting with the polymer matrix), and “free” water (in large pools). The majority of water is in the bound state. It is possible to evaluate the control-release performance of the product from the size of the pores, the uniformity of dispersion and the time course of detergent-water exchange.

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1. Mateescu, G.D. and Dular, Terri, Oxygen-17 NMR Imaging, ENC (Experimental NMR Conference) 28, 73a (1987).
2. Mateescu, G.D., Yvars, G.M. and Dular, T., Oxygen-17 MRI, Soc.Magn.Res.Med. (SMRM),6, 929a. (1987).
3. Mateescu, G.D., Yvars, G., Pazara, D. and Alldridge, N., 17O/1H NMR Microscopy, ENC, 29, 189, (1988).
4. Mateescu, G.D., Yvars, G.M., Pazara, D., LaManna, J., Lust, D., McKracken, K., Mattingly, M. and Kuhn, W., Oxygen-17: A Physiological, Biochemical and Anatomical MRI Contrast Agent, SMRM 7, 600 (1988).
5. Mateesacue, G D., Yvars, G.M. and Dular, Terri, Water, Ions and 17O MRI, Water and Ions in Biological Systems, edited by Lauger, P. (Birkhauser Publi-shers, Basel, 1988), p.239250.
6. Mateescu, G.D., Yvars, G.M., Pazara, D.I., Alldridge, N.A., LaManna, J.C., Lust, W.D., Mattingly, M. and Kuhn, W., Combined 17O/1H MR Microscopy in Plants, Animals and Materials, Synthesis and Applications of Isotopically Labeled Compounds, Baillie, & Jones, , Eds. (Elsevier, 1989) 499508.
7. Mateescu, G.D., Yvars, G., Maylish-Kogovsek, L., LaManna, J., Lust, W.D. and Sudilovsky, D., 17O MRI and MRS of the Brain, the Heart and Coronary Arteries, SMRM 8, 659 (1989).
8. Mateescu, G.D. and Yvars, G.M., Oxygen-17 MR Imaging: Theory and Experiment, ENC 30, 197a (1989).
9. Mateescu, G.D., Yvars, G. M., LaManna, J.C., Lust, W.D. and Sudilovsky, D., Oxygen-17 MRS:in vivo Evaluation of Water Up-take and Residence Time in the Mouse Brain after Injection of O-17 Labelled Water, SMRM 9, 1236 (1990).
10. Mateescu, G.D., Yvars, G.M., LaManna, J.C., Lust, D.W. and Sudilovsky, D., Volume Selected 17O Spectroscopy in Experimental Cerebral Ischemia, ENC, 31, 205a (1990).
11. Mateescu, G.D., Oxygen-17 Imaging of Non-Biological Materials, FACSS 17, 127a (1990).
12. a) ProMacR is a registered trade mark of B.F. Goodrich Co. b) Sobek, A.A., Benedetti, D.A., Rastogi, V.J., Proc. Mining and Reclamation Conf., Vol.1, 3342 (1990).

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Oxygen-17 and Proton Mr Microscopy in Materials Analysis

  • G.D. Mateescu (a1), R.A. Kinsey (a2) and G.M. Yvars (a1)

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