Fig. 3.

NIRS-DCS BFI versus ASL-MRI. We compared DCS BFI calculations of muscle perfusion against arterial spin-labeling MRI during (a) reactive hyperemia and (b) plantar flexion exercise. The unadjusted BFI calculation consistently underestimated ASL-measures of muscle perfusion, whereas the ${\mathrm{Adj}}_{\mathrm{LIN}}$ and $\mathrm{BFI}\text{-}{\mathrm{Adj}}_{\pi r2}$ calculations were much closer. (c), (d) Mean residuals (BFI – ASL) throughout the recovery periods.