Evaluation of treatment response in patients with recurrent grade 4 glioma using hyperpolarized [1-13C]pyruvate MRI

Hyperpolarized (HP) [1-13C]pyruvate MRI allows for noninvasive assessment of dynamic metabolic activity in the brain and has potential for monitoring treatment response in gliomas. This exploratory study evaluated the ability of serial HP [1-13C]pyruvate MRI to detect treatment-related metabolism and evaluate early therapeutic response. Twenty patients with recurrent grade 4 glioma undergoing cytotoxic, antiangiogenic, and targeted chemotherapies underwent serial HP [1-13C]pyruvate MRI in conjunction with routine clinical MRI.

Percentage changes were calculated from the group mean at each timepoint. The lactate/pyruvate ratio in the normal-appearing white matter (NAWM) increased by 14.3% at 1-month in the bevacizumab-treated group, whereas it decreased by 13.1% at 2-month in the everolimus-treated group. Within the T2-lesion, the NAWM-normalized lactate/pyruvate ratio increased by 24.3% in the bevacizumab-treated group and decreased by 7.6% in the everolimus-treated group.

Among patients with shorter 6-month progression-free survival, the NAWM-normalized lactate/pyruvate increased by 18.2% from baseline to 2-month follow-up. This exploratory proof-of-feasibility study demonstrates that serial HP [1-¹³C]pyruvate MRI can detect measurable longitudinal metabolic changes in recurrent grade 4 glioma during treatment. Larger, prospective studies with more homogeneous treatment cohorts are needed to validate these observations and determine their clinical utility as imaging biomarkers of treatment response.

We sincerely thank the patients who participated in this study for their time, commitment, and invaluable contribution to this research. This study was supported by NIH P01CA118816, NIH P50CA097257, and the Glioblastoma Precision Medicine Program, with technical assistance from NIH P41EB013598. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA Sana Vaziri, Janine M.

Autry, Marisa LaFontaine, Javier Villanueva-Meyer, Daniel B. Vigneron & Yan Li UCSF/UC Berkeley Graduate Program in Bioengineering, University of California San Francisco, San Francisco, CA, USA Janine M. Vigneron & Yan Li Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA Javier Villanueva-Meyer, Nancy A.

Clarke Department of Neurology, University of California San Francisco, San Francisco, CA, USA Nancy A. Oberheim-Bush & Jennifer L. Clarke The authors declare no competing interests.