In Vivo Comparison of Total & Hyperpolarized Lactate Levels Assessed by Localized 1H MRS & Hyperpolarized 13C MRSI in Glioblastoma Models at 14.1Tesla

¹Radiology, University of California, San Francisco, San Francisco, CA, United States; ²Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States; ³Pathology, University of California, San Francisco, San Francisco, CA, United States Localized ¹H MRS and hyperpolarized (HP) ¹³C MRSI were performed in vivo at 14.1Tesla to assess total and HP lactate levels, respectively, in two orthotopic models of glioblastomas with significantly different intracellular lactate levels: U87IDHmut[Lac]>U87IDHwt[Lac]. In line with the intracellular levels, in vivo ¹H lactate levels were significantly higher in U87IDHmut. In contrast, HP lactate-to-noise and lactate-to-pyruvate ratios from the same tumor voxel were not significantly different between the cell lines. This discrepancy confirms that HP ¹³C MRSI and ¹H MRS provide complementary information, the ¹H-detected lactate level not being a dominant factor in the detected HP lactate production.