Clinical application of ¹H MRS in the human brain at 7T

Proton magnetic resonance spectroscopy (¹H MRS) enables non-invasive biochemical sampling of tissues, potentially aiding diagnosis, prognosis and monitoring of various pathologies, while providing novel imaging biomarkers. Ultra-high-field (UHF) imaging at 7 tesla (7T) benefits from improved spectral dispersion due to an increase in chemical shift differences between metabolites, and a higher signal-to-noise ratio (SNR), making ¹H MRS at 7T a particularly promising diagnostic tool for identifying and separating metabolites not clearly resolved at lower field strengths. However, ¹H MRS at UHF presents technical challenges related to the short RF wavelength at 7T, resulting in B₁ transmit field inhomogeneity, and the increased magnetic susceptibility gradients leading to B₀ field inhomogeneity. Appropriate MRS methods are required to address these issues. In this article, we describe the technical aspects and challenges of ¹H MRS at 7T, based on the experience in our centre, where single voxel ¹H MRS has featured prominently in clinical 7T research applications for several years. We present data from six patients with glial tumours, including three who were post-operative, in whom post-surgical metalware affects the specific absorption rate (SAR), along with two patients with neuroinflammatory conditions and two with neurodegenerative diseases. The potential clinical use of ¹H MRS for these pathologies and its possible integration as a promising biomarker into advanced imaging pathways are discussed.