Gregory J. Wilson1, Charles S. Springer, Jr. 2, Mark Woods2, 3, Sarah Bastawrous, 14, Puneet Bhargava, 14, Jeffrey H. Maki1
1Radiology, University of Washington, Seattle, WA, United States; 2Advanced Imaging Research Center, Oregon Health and Science University, Portland, OR, United States; 3Chemistry, Portland State University, Portland, OR, United States; 4Radiology, Puget Sound VAHCS, Seattle, WA, United States
Measurements of longitudinal relaxation rates (R1) of 1H2O in whole blood with gadolinium-based contrast reagent concentrations ([CR]) in the range of 2 to 18 mM provide evidence of water exchange across the erythrocyte cell membrane. The dependence of R1 on [CR] was accurately predicted by the two-site-exchange (2SX) model in the fast exchange regime (FXR). Contrast reagents with high protein binding affinity (gadobenate dimeglumine and gadofosveset trisodium) were more sensitive to the water exchange kinetics because of their higher relaxivities. This sensitivity to water exchange across the cell membrane may enable future studies of erythrocyte function.