Thus, monitoring the waning of GLUD1 and GPT2 expression levels by measuring their end substrates by this non-invasive imaging technique may potentially detect the progression of lower-grade astrocytomas harboring IDH1 mutation towards secondary GBM, and it would, therefore, allow a change in the therapeutic strategy for these patients. The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).