Dynamic quantitative susceptibility mapping to measure cardiac pulsation and respiration induced endogenous brain signal changes

Motivation: The contribution of physiologically induced dynamic magnetic susceptibility within the brain to the blood oxygen level dependent (BOLD) signal used for functional imaging has never been quantified. Goal(s): Our goal was to measure the brain’s dynamic magnetic susceptibility signal as a function of the cardiac and respiratory cycles using quantitative susceptibility mapping (QSM). Approach: We developed and evaluated an image processing framework to generate dynamic susceptibility maps over the course of cardiac pulsation and respiration. Results: We demonstrated that QSM is sensitive to physiologically induced susceptibility changes and that our framework can be used to measure these dynamics. Impact: The influence of physiologically induced dynamic magnetic susceptibility on BOLD signal could impact the derivation/interpretation of BOLD-based functional connectivity. Significant susceptibility changes could indicate a need to modify existing functional mapping approaches whereas the reverse would validate current techniques.