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Sodium-23 Magnetic Resonance Imaging of the Eye and Lens
William H. Garner, Sadek K. Hilal, Sang-Wook Lee and Abraham Spector
Proceedings of the National Academy of Sciences of the United States of America
Vol. 83, No. 6 (Mar. 15, 1986), pp. 1901-1905
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/26901
Page Count: 5
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In order to develop a better understanding of cataract and to evaluate the effectiveness of potential drugs, noninvasive techniques must be devised to detect early metabolic changes. As a prelude to these goals, sodium-23 imaging experiments operating at 29.8 MHz (2.7 teslas) were performed on the bovine eye and lens. A spatially localized transverse relaxation time (T2)-weighted spin-density map of the sodium-23 within the lens is presented, with a resolution better than 250 μ m. Due to the presence of short-T2 (3 msec) components within the lens, only the use of the planar-integral projection reconstruction (PPR) imaging scheme allowed sufficiently short echo-times (1 msec) to permit sodium-23 signal detection. These noninvasive imaging results show differences in the apparent sodium concentration within the lens that are consistent with separate, invasive measurements of sodium concentration. Separate analysis (with no spatial localization) at 79.4 MHz (7.2 teslas), using a shift reagent (dysprosium) to distinguish extracellular from intracellular sodium, indicates that ≈ % of the detected sodium-23 signal is intracellular. These results are consistent with observations based on invasive measurements and further support the existence of the pump-leak system and a sodium gradient within the lens.
Proceedings of the National Academy of Sciences of the United States of America © 1986 National Academy of Sciences