Oxygen‐17 compounds as potential NMR T2 contrast agents: Enrichment effects of H217O on protein solutions and living tissues

Abstract

The isotopic enrichment of solutions, living tissues, and organisms with oxygen-17 in the form of H₂¹⁷O shortens their proton NMR transverse relaxation times (T₂) and produces changes in NMR image intensity. The transverse relaxation rate (1/T₂) was found to be linearly dependent on the H₂¹⁷O concentration in biological solutions up to 5% enrichment. The longitudinal relaxation time (T₁) is not affected by enrichment. Equal concentrations of H₂¹⁷O do not produce the same magnitude of T₁ change in all physiological environments. The reasons for these differences are discussed. The results suggest that certain oxygen-17 compounds should be explored as “contrast agents” in magnetic resonance imaging. © 1987 Academic Press, Inc.