Briefly, Saxena et al. performed in vivo measurements of absolute hemoglobin concentrations [i.e. oxygenated ([HbO2]), deoxygenated ([Hb]), and total ([HbT] = [HbO2]+[Hb])] and hemoglobin oxygen saturation (StO2 = [HbO2]/[HbT]) in mouse brain using a CW approach and reported a strong correlation between brain tumor size and [Hb]. The gene discussed is GSTM1; the disease is brain neoplasm.