a Normalized with the corresponding water reference signals, MR spectra from 9L and F98 tumors were averaged at week 3 (n = 5 for 9L, reduced n = 3 for F98 due to MRS quality issues) and week 4 (n = 4 for both 9L and F98) post-tumor implantation. b Creatine concentrations quantified from 1H-MRS is shown. Cho choline, Cr creatine, NAA N-acetylaspartic acid, Lac lactate.