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Abstract #4459

High Concentration Relaxivities of Four Gadolinium-Based Contrast Reagents in ex Vivo Physiologic Whole Blood and Plasma at 1.5 and 3.0T

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

To characterize relevant relaxation rates for CE-MRA, we have measured T1, T2, and T2* for four approved contrast agents in ex vivo whole blood and plasma under physiologic conditions and concentrations up to 18 mM at 1.5T and 3.0T. Protein binding and water exchange across the erythrocyte membrane create deviations from a simple linear dependence of R1 (= 1/T1) on contrast agent concentration in whole blood. T2* was found to be substantially shorter in whole blood than in plasma. Accurate relaxation rates help explain diminishing return of contrast agent dose, and allow us to better optimize dosing strategies for CE-MRA.