Several new approaches to assess metabolism in intact tumors, particularly with new imaging approaches, have been used in humans and experimental models to report subtype-selective metabolic properties, some of which correlate with therapeutic sensitivities. MRS, magnetic resonance spectroscopy; D-2HG, D-2-hydroxyglutarate; mIDH, mutant isocitrate dehydrogenase; MCT1, monocarboxylate transporter-1; 18F-BnTP, 4-[18F]fluorobenzy7l-triphenylphosphonium; Gln, glutamine; PET, positron emission tomography; GLS, glutaminase.