Figure 6.

The susceptibility effect parameter $\beta$ obtained for various vessel diameters corresponding to capillaries at different field strengths for (a) Monte-Carlo simulations with freely diffusing protons (2% volume fraction); (b) Monte-Carlo simulations with no proton exchange between intra- and extravascular spaces (2% volume fraction); (c) Monte-Carlo simulations with a cylinder volume fraction of 4% instead of 2%; (d) Static dephasing with protons not moving (2% volume fraction). (e) for BOLD $\mathrm{\Delta }\chi$ range.