Figure 2.

Monte Carlo Bloch simulation results. (a) Calculated microscopic B0 inhomogeneity (Hz) in the numerical voxel used in our Monte Carlo Bloch simulations. A 2D cut through the 1×1×1 mm³ voxel is shown. (b) Absolute functional signal change for STFR over a range of TRs and flip angles with and without diffusion. (c) Absolute functional signal change for STFR with respect to flip angle for several TRs used in our experiment. These simulations predict that STFR can produce a functional signal. The absolute signal change is maximized around 20°. “Turning off” spin diffusion has a relatively small impact on the functional signal, indicating that functional contrast in STFR arises primarily from the interaction between microscopic off-resonance and the tailored tip-up pulse, and not from spin diffusion. (d) The absolute signal change when the mean phase mismatch in a voxel is not 0 (equivalent to the weighted integration over a narrow spectrum off the center in Fig. 1-(b)). The functional signal change is maximized when mean phase mismatch for a voxel is 0.