The Effects of Equilibrium Intercompartmental Water Exchange Kinetics on MRI Estimation of Tissue Concentration of Contrast Agents

TL;DRAbstract

-R* 2 TE ~ 1. The relaxation rates of the blood R1b and extracellular space R1e were varied over the range (0.5, 20.0) s -1 , and the intracellular water R1i was set to 0.56 s -1 (6). The exchange rate from blood to the extracellular space for a typical cerebral tumor was assigned to kbe = 10.0 s -1 for the fractional blood water content ub = 0.. The range of transcellular rate of exchange was (0.5- 10.0) s -1 .This range is chosen in congruence with measured rate of exchange of kie = 1.81 s -1 for a fractional intracellular water content, ui ~ 0.8; respectively, in a rat brain (6). Simulations were performed using a program written in ANSI C and implemented in a UNIX system. Gaussian-distributed noise was added to the TOMROP signal using the Box and Muller algorithm. The simulated data was then sampled as in our experiment, fitted using established in-house techniques, and estimates of tissue R1 were then plotted against the relaxation rate of the extracellular space R1e. In MRI proce

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