Deuterium metabolic imaging for assessing response to chemoradiotherapy in high grade glioma: a multisite study

BackgroundThe early assessment of successful treatment response in high-grade glioma is challenging using conventional MRI, due to phenomena such as pseudoprogression which can mimic tumor progression. New methods are needed to evaluate therapeutic efficacy rapidly and accurately. Deuterium Metabolic Imaging (DMI) is a novel, non-invasive technique that can map downstream glucose metabolism in vivo. This study aimed to evaluate the utility of DMI for assessing metabolic response to chemoradiotherapy (ChRT) in glioma patients. MethodsIn this prospective two-site study, 18 patients with high-grade glioma underwent 3 T DMI before and after ChRT. Following oral administration of [6,6-2H2]glucose, 3D metabolic maps of 2H-glucose (Gluc), 2H-lactate (Lac), and 2H-glutamate+glutamine (Glx) were acquired. Ratios of Lac/Gluc and Glx/Gluc were calculated in the tumor and normal-appearing brain parenchyma to assess glycolytic and oxidative metabolism, respectively. ResultsBefore treatment, the tumor Glx/Gluc ratio was significantly lower than in the contralateral brain tissue. Following ChRT, a significant decrease in the normalized Lac/Gluc ratio was observed within the tumor volume, indicating a reduction in glycolysis. An important finding was that a lower pre-treatment normalized Glx/Gluc ratio in the tumor was a significant predictor of shorter progression-free survival (median 98 vs. 351 days, p=0.034). ConclusionsDMI identified metabolic changes in high-grade gliomas responding to ChRT. Reduced oxidative metabolism pre-treatment was associated with a poorer prognosis, while post-treatment decreases in glycolysis were demonstrated following therapy. DMI is a promising tool for non-invasively stratifying patients and monitoring treatment efficacy.