Simulating BOLD fMRI transverse relaxation at 3 T: How accurate is the infinite cylinder model of blood vessels?

Simulations of the BOLD signal have provided invaluable insights into the biophysical underpinnings of BOLD contrast. Typically, infinite cylinders are used to represent the vasculature, although, in reality the vasculature is much more complex. In this study, we compared several biophysical modelling techniques for simulating the BOLD effect, including using Vascular Anatomical Networks (VANs) to model the capillary bed with realistic geometry. We found the majority of the different simulation approaches produced relatively consistent results with each other. The VAN simulations were consistent with the infinite cylinders, suggesting that infinite cylinders are a reasonable approximation to more realistic vascular models.