Analysis of the robustness and dynamics of spin-locking preparations for the detection of oscillatory magnetic fields

TL;DR

This paper investigates the robustness of spin-lock MRI preparations for detecting oscillatory magnetic fields, focusing on their response to field inhomogeneities and potential for clinical neuronal current imaging.

Contribution

It analyzes the dynamics of three spin-lock protocols and demonstrates that composite spin-locks are more resilient to field variations, advancing MRI techniques for brain activity detection.

Findings

Composite spin-locks are more robust against field inhomogeneities.

The method can recover spectral components of complex signals.

Simulation results support potential clinical applications.

Abstract

Extracting quantitative information of neuronal signals by non-invasive imaging is an outstanding challenge for understanding brain function and pathology. However, state-of-the-art techniques offer low sensitivity to deep electrical sources. Stimulus induced rotary saturation (SIRS) is a recently proposed magnetic resonance imaging (MRI) sequence that detects oscillatory magnetic fields using a spin-lock preparation. Phantom experiments and simulations proved its efficiency and sensitivity, but the susceptibility of the method to field inhomogeneities is still not well understood. In this study, we simulated and analyzed the dynamic of three spin-lock preparations and their response to field inhomogeneities in the presence of a resonant oscillating field. We show that the composite spin-lock preparation is more robust against field variations within the double resonance effect. In addition, we tested the capability of the chosen composite spin-lock preparation to recover information about the spectral components of a composite signal. This study sets the bases to move one step further towards the clinical application of MR-based neuronal current imaging.