Field strength dependence of R1 and R2* relaxivities of human whole blood to ProHance, Vasovist, and deoxyhemoglobin.

This study has measured the longitudinal and transverse (T2* relaxivity curves for ProHance (Gadoteridol), Vasovist (Gadofosveset) and deoxyhemoglobin at 1.5, 3.0, and 7.0 Tesla. The plots of R(1) versus both contrast agent and deoxyhemoglobin concentration were linear. The plots of R2* versus deoxyhemoglobin concentration showed a quadratic dependence. R2* versus contrast agent concentration showed a parabolic dependence with a minimum occurring at contrast agent concentrations of approximately 1.5 mM, corresponding to an accessible concentration in vivo. Monte Carlo simulations were performed to support the hypothesis that the minimum results from the susceptibility of the red blood cells being matched to the susceptibility of the plasma. Relaxivity values (s(-1)mM(-1)) for R2* and R1 for all agents and all three field strengths are given