Fig. 4

Estimates of the exchange model parameters in the ischemic region. The exchange model parameters were estimated by fitting to the diffusion-weighted imaging data in the ischemic region. Exchange-time (a), water exchange time between the intracellular and extracellular space; α (b), a parameter reflecting the mean cell volume; F_in (c), signal fraction from intracellular space. D_ex (d), apparent diffusion coefficient for the extracellular space. The plots show the mean for each wild-type (WT) (blue) and aquaporin-4 knockout (AQP4-KO) (red) mouse, while the black bars correspond to the mean over animals. * and ** indicate significant differences in the estimates from the WT and AQP4-KO mice (a, p = 0.006; b, p = 0.003; c, p = 0.004; d, p = 0.044; unpaired t test)