GSTM1 and central nervous system cancer: Specifically, Figs. 4(d) and 4(e) display spatially resolved maps of concentration changes in total hemoglobin (Δ[HbT]=Δ[HbO2+Hb]) and differential cytochrome c oxidase (Δ[DiffCCO]=Δ[oxCCO−redCCO]), respectively, computed from a grade 4 glioma sample.