Multinuclear Magnetic Resonance Spectroscopy at Ultra-High-Field: Assessing Human Cerebral Metabolism in Healthy and Diseased States

Abstract

The brain is a highly energetic organ. Although the brain can consume metabolic substrates, such as lactate, glycogen, and ketone bodies, the energy metabolism in a healthy adult brain mainly relies on glucose provided via blood. The cerebral metabolism of glucose produces energy and a wide variety of intermediate metabolites. Since cerebral metabolic alterations have been repeatedly implicated in several brain disorders, understanding changes in metabolite levels and corresponding cell-specific neurotransmitter fluxes through different substrate utilization may highlight the underlying mechanisms that can be exploited to diagnose or treat various brain disorders. Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure tissue metabolism in vivo. 1H-MRS is widely applied in research at clinical field strengths (≤3T) to measure mostly high abundant metabolites. In addition, X-nuclei MRS including, 13C, 2H, 17O, and 31P, are also very promising. Exploiting the higher sensitivity at ultra-high-field (>4T; UHF) strengths enables obtaining unique insights into different aspects of the substrate metabolism towards measuring cell-specific metabolic fluxes in vivo. This review provides an overview about the potential role of multinuclear MRS (1H, 13C, 2H, 17O, and 31P) at UHF to assess the cerebral metabolism and the metabolic insights obtained by applying these techniques in both healthy and diseased states.

In vivo Volumetric, DTI and 1H MRS Rat Brain Protocol for Monitoring Early Neurodegeneration and Efficacy of the Used Therapy

“…This assumption would be consistent with our findings, as we did not observe any significant changes in FA. We could not detect any change in the concentration of NAA, which is considered a marker for neuronal functionality, and a decrease in the NAA levels occurs in advanced Alzheimer's disease [54], [55], which is also related to a decrease in the volume of the hippocampal region of the brain. In our study, we observed the reduction of the hippocampal region without the reduction in NAA concentration in the measured part of this region, but an increase in mIns was observed.…”

Transcellular Barriers to Glucose Delivery in the Body

“…Thus, this review focuses on those cellular barriers to glucose delivery and does not address the end stage glucose utilization at the levels of the brain, muscles, heart, and other key glucose consumers. The reader is referred to recent scholarly reviews on those topics (4)(5)(6)(7).…”