χ-separation: Magnetic susceptibility source separation toward iron and myelin mapping in the brain
Hyeong-Geol Shin,
Jingu Lee,
Young Hyun Yun,
Seong Ho Yoo,
Jinhee Jang,
Se-Hong Oh,
Yoonho Nam,
Sehoon Jung,
Sunhye Kim,
Masaki Fukunaga,
Woojun Kim,
Hyung Jin Choi,
Jongho Lee
Affiliations
Hyeong-Geol Shin
Laboratory for Imaging Science and Technology, Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
Jingu Lee
AIRS Medical Inc., Seoul, Republic of Korea
Young Hyun Yun
Department of Medicine, Anatomy and Cell Biology, Seoul National University College of Medicine, Seoul, Republic of Korea
Seong Ho Yoo
Department of Forensic Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
Jinhee Jang
Department of Radiology, Seoul St Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
Se-Hong Oh
Division of Biomedical Engineering, Hankuk University of Foreign Studies, Yongin, Republic of Korea
Yoonho Nam
Division of Biomedical Engineering, Hankuk University of Foreign Studies, Yongin, Republic of Korea
Sehoon Jung
Research Institute of Industrial Science and Technology, Pohang, Republic of Korea
Sunhye Kim
Research Institute of Industrial Science and Technology, Pohang, Republic of Korea
Masaki Fukunaga
Division of Cerebral Integration, National Institute for Physiological Sciences, Okazaki, Japan
Woojun Kim
Department of Neurology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
Hyung Jin Choi
Department of Biomedical Sciences, Anatomy and Cell Biology, Neuroscience Research Institute, Wide River Institute of Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
Jongho Lee
Laboratory for Imaging Science and Technology, Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea; Corresponding author.
Obtaining a histological fingerprint from the in-vivo brain has been a long-standing target of magnetic resonance imaging (MRI). In particular, non-invasive imaging of iron and myelin, which are involved in normal brain functions and are histopathological hallmarks in neurodegenerative diseases, has practical utilities in neuroscience and medicine. Here, we propose a biophysical model that describes the individual contribution of paramagnetic (e.g., iron) and diamagnetic (e.g., myelin) susceptibility sources to the frequency shift and transverse relaxation of MRI signals. Using this model, we develop a method, χ-separation, that generates the voxel-wise distributions of the two sources. The method is validated using computer simulation and phantom experiments, and applied to ex-vivo and in-vivo brains. The results delineate the well-known histological features of iron and myelin in the specimen, healthy volunteers, and multiple sclerosis patients. This new technology may serve as a practical tool for exploring the microstructural information of the brain.
