This research study is for Glioblastoma (GBM) patients who will be beginning Optune as part of their clinical care, which is a novel treatment that utilizes - tumor treating fields (TTFields), (aka, electrical therapy), which has shown to improve overall survival in large multi-center trials. As a part of this study, participants will either receive Optune with standard array mapping (based on regular contrast enhanced MRI) or an alternative (more precise) array mapping based on sophisticated state of the art MRI techniques including whole brain spectroscopy. Whole brain MRI spectroscopy provides additional metabolic information to map out the full extent of tumor spreading within the brain (far beyond from what is seen on regular MRI), by identifying certain metabolites that are present in cancer cells versus healthy tissue. This study is being performed to show whether alternative array mapping improves treatment outcomes, as opposed to the standard array mapping, by maximizing delivery of TTFields dose, thereby achieving more effective tumor cell killing, decreasing the rate of local recurrence, and improving the overall survival as well as quality of life measures.