MR Spectroscopy

NMR spectroscopy (MRS) enables the detection of signals of atomic nuclei with spin I≠0 bound to biomolecules. Without polarization techniques the abundance of those compounds in living tissue must be quite high to resolve the resonances – the detection limit for in vivo NMR is a concentration of ≥0.1 mM. The biochemical information is obtained non-invasively and without ionizing radiation.

Several spin species yield interesting multiline in vivo NMR spectra in acquisition times of a few minutes, for example spin-½ nuclei like ¹H (proton; information about brain metabolites) and ³¹P (information about energy metabolism, membrane phospholipid turnover and intracellular pH).

The combination of MRS with MR imaging (MRI) techniques leads to MR spectroscopic imaging (MRSI), which yields maps of the regional abundance and distribution of metabolites in tissue. Compared to conventional ¹H MRI of tissue water, ¹H MRSI of small intracellular metabolites suffers from an at least 10⁴-times smaller sensitivity.

The introduction of ultrahigh–field (UHF) MR scanners (magnetic field strength B₀ ≥ 7 Tesla) opened new perspectives for MRI, MRS, and MRSI owing to increased sensitivity and spectral resolution. To promote clinical applicability of spectroscopy, our research group focuses on the development of high-resolution MRS and MRSI at UHF, where specific technical challenges occur.