Carbon and Deuterium MRI studies of human brain metabolism

Abstract

Metabolic changes to the brain can be due to brain disease causing impaired functioning. Imaging of the metabolic processes is an emerging area of research that can allow for greater understanding of the brain disease whilst offering clinical potential for improved diagnosis. Hyperpolarized (HP) 13C pyruvate and Deuterium Metabolic Imaging (DMI) are two metabolic imaging techniques that allow for the metabolic uptake of the brain to be measured alongside the downstream metabolic processes. The work begins with the implementation of imaging techniques to clinical field strengths for brain imaging through phantom and human studies. Modifications to the acquisition and hardware were evaluated to optimize imaging for human brain studies. Subsequently a comparison between DMI and HP 13C pyruvate imaging was made in the healthy human brain demonstrating the complementary but differing information that they provide. Spectroscopic data was evaluated using HP 13C Pyruvate where the pH was measured in the and pyruvate carboxylase activity was measured in the healthy brain. In the diseased brain, DMI was applied in Alzheimer's Disease (AD) patients in a pilot study evaluating the use of the technique. The utility of DMI was demonstrated through unlocalized spectral acquisitions where altered metabolic measurements were seen in patients compared to controls. In addition, differences in measurements were seen between differently aged healthy control groups. Finally, DMI and HP 13C pyruvate was applied in glioblastoma (GBM) patients to assess metabolic changes following treatment after surgical resection. Metabolic differences were seen in the GBM patients’ images using both techniques with metabolic changes following treatment seen. Alongside metabolic measurements, pH was measured using HP 13C pyruvate in one patient where more acidic values were seen at baseline compared to healthy controls before returning to healthy levels post-treatment.