Visualization of in-vivo brainstem myeloarchitecture via χ-separation at 7T

Motivation: Brainstem regulates vital functions and connects the brain and spinal cord. Investigating its detailed structure and alteration, particularly in myelin-related areas, is important in understanding their functions and tracking neurodegenerative diseases. Goal(s): We aim to generate high-resolution myelin-distribution maps using χ-separation and validate them with histology images. Approach: High-resolution (<0.5 mm) χ-separation maps were generated utilizing the 7T χ-separation method along with modified resolution generalization method. The resulting diamagnetic susceptibility maps are compared with myelin-stained maps. Results: We produced high-quality and high-resolution 𝜒-separation maps, closely aligning with myelin-stained images and capturing myelin-rich structures such as corticospinal fibers, transverse pontine fibers, and medial lemniscus. Impact: This study demonstrates that 7T χ-separation can generate high-resolution (<0.5 mm) diamagnetic susceptibility (mostly myelin) maps of in-vivo brainstem, closely matching myelin histology. This may benefit detailed analysis of structure and myelin concentration changes in brainstem, relevant to neurodegenerative diseases.