These biomarkers are based on the increase of an index combining choline / Creatine (Cho / Cr), Glx / Cr (Glutamine and glutamate / Creatine), NAA / Cr (N acetyl aspartate / Creatine) and lactate / Cr ratios. The long-term objective is to predict the survival of these relapsed GBM patients at an early stage and to identify responder patients who would benefit from this expensive molecule and avoid using it in non-responding patients