A human brain atlas of χ-separation (chi-separation) for normative iron and myelin distributions

Motivation: Abnormal iron and myelin distributions are associated with neurodegenerative diseases. An advanced susceptibility mapping technique, χ-separation, can disentangle paramagnetic iron and diamagnetic myelin contributions in quantitative susceptibility mapping. Goal(s): In this study, a normative χ-separation atlas is created from 106 healthy volunteers. Approach: To this end, individual χ-separation maps were registered to a common space and averaged across subjects. Results: The resulting χ-separation atlas reflects well-known iron and myelin-rich structures in the brain. The analysis based on regions of interest revealed distinct characteristics of normative para- and diamagnetic susceptibility profiles throughout subcortical nuclei, thalamic nuclei, and white matter fibers. Impact: Our χ-separation atlas would be utilized as a reference for imaging susceptibility in the brain and may assist in accurate localization of targets for intervention such as deep brain stimulation or high-intensity focused ultrasound.