title: Improved estimation of myelin water fraction using complex model fitting.
abstract: In gradient echo (GRE) imaging, three compartment water modeling (myelin water, axonal water and extracellular water) in white matter has been demonstrated to show different frequency shifts that depend on the relative orientation of fibers and the B0 field. This finding suggests that in GRE-based myelin water imaging, a signal model may need to incorporate frequency offset terms and become a complex-valued model. In the current study, three different signal models and fitting approaches (a magnitude model fitted to magnitude data, a complex model fitted to magnitude data, and a complex model fitted to complex data) were investigated to address the reliability of each model in the estimation of the myelin water signal. For the complex model fitted to complex data, a new fitting approach that does not require background phase removal was proposed. When the three models were compared, the results from the new complex model fitting showed the most stable parameter estimation.
authors: Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea; Department of Electrical and Computer Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of Korea.
authors: Yoonho
authors: Y
authors: Nam
authors: Department of Electrical and Computer Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of Korea. Electronic address: jonghoyi@snu.ac.kr.
authors: Jongho
authors: J
authors: Lee
authors: Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea.
authors: Dosik
authors: D
authors: Hwang
authors: Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea. Electronic address: donghyunkim@yonsei.ac.kr.
authors: Dong-Hyun
authors: DH
authors: Kim
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008959:Models, Neurological; D009186:Myelin Sheath; D015203:Reproducibility of Results; D014867:Water / Q000032:analysis; D055815:Young Adult
chemical_list: D014867:Water
keywords: B(0) field inhomogeneity; Fiber orientation; Frequency offset; Myelin water; T(2)(⁎) relaxation; White matter