FIGURE 4.

Simulated percent error in measured T_1ρ relaxation times and spatial blurring using tailored VFA scheduling. The dots mark the assumed T₁ (1200 ms) and T_1ρ (75 ms) relaxation times when calculating the tailored VFA schedules. A, Plots of T_1ρ percent error as a function of the true T₁ and T_1ρ relaxation times of brain tissue after fitting five TSLs (0, 20, 40, 60, and 80 ms) to a mono-exponential decay curve. The T_1ρ quantification error increases as VPS increases but is ≤ 2% up to VPS = 256. B, Plots of the maximum FWHM values across all TSL image point spread functions (PSFs). There is relatively little PSF blurring with FWHM ≤ 1.07 pixels for all cases. C, Simulated image and T_1ρ map profiles. The leftmost plot is for the ideal case, where the true T₁ and T_1ρ relaxation times match those assumed when generating the tailored VFA schedules (corresponding to the dots in [A] and [B]). The next four plots are the extreme pairs of T₁ and T_1ρ values used for the simulations (corresponding to the corners of the plots in (A) and (B)). Black lines are for VPS = 64 and red lines are for VPS = 256. The T_1ρ relaxation times in the middle of the map profiles are indicated above the plots for both VPS = 64 (black font) and VPS = 256 (red font)