Hemoglobin (Hb) contains four polypeptides forming globin and each polypeptide binds to a heme‐Fe group (ferroprotoporphyrin), making Hb an oxygen‐sensitive contrast agent (Figure8A,B).[95] Hb can shift between diamagnetic oxyhemoglobin (HbO2) and paramagnetic deoxyhemoglobin under different oxygen concentration, producing blood oxygenation level‐dependent image contrast.[96] It is a powerful tool to study neuroscience,[97] tumor hypoxia,[98] perfusion and ischemia,[99] and skeletal muscle,[100] among others. Here, GSTM1 is linked to neoplasm.