Electrocardiogram-triggered, higher order, projection-based B(0) shimming allows for fast and reproducible shim convergence in spinal cord (1) H MRS

Abstract

(1) H MRS allows insight into the chemical composition of the central nervous system. However, as a result of technical challenges, it has rarely been applied to the spinal cord. In particular, the strong susceptibility changes around the spinal cord and the pulsatile flow of the cerebrospinal fluid lead to distinct B(0) field distortions which often considerably degrade the spectral quality. Hence, B(0) shimming is one of the main challenges in (1) H MRS of the spinal cord. Electrocardiogram (ECG)-triggered, higher order, projection-based B(0) shimming was introduced and compared with both conventional projection-based B(0) shimming and B(0) shimming based on ECG-triggered, three-dimensional B(0) field mapping. The linewidth of the unsuppressed water peak was used to evaluate the reproducibility and the potential improvement to B(0) homogeneity. The use of ECG-triggered projection-based B(0) shimming in combination with ECG triggering during preparation phases and triggering during acquisition of the spectra is the most robust method and thus helps to improve the spectral quality for MRS of the spinal cord.