title: Direct magnitude and phase imaging of myelin using ultrashort echo time (UTE) pulse sequences: A feasibility study.
abstract: In this paper, we aimed to investigate the feasibility of direct visualization of myelin, including myelin lipid and myelin basic protein (MBP), using two-dimensional ultrashort echo time (2D UTE) sequences and utilize phase information as a contrast mechanism in phantoms and in volunteers. The standard UTE sequence was used to detect both myelin and long T2 signal. An adiabatic inversion recovery UTE (IR-UTE) sequence was used to selectively detect myelin by suppressing signal from long T2 water protons. Magnitude and phase imaging and T2* were investigated on myelin lipid and MBP in the forms of lyophilized powders as well as paste-like phantoms with the powder mixed with D2O, and rubber phantoms as well as healthy volunteers. Contrast to noise ratio (CNR) between white and gray matter was measured. Both magnitude and phase images were generated for myelin and rubber phantoms as well white matter in vivo using the IR-UTE sequence. T2* values of ~300μs were comparable for myelin paste phantoms and the short T2* component in white matter of the brain in vivo. Mean CNR between white and gray matter in IR-UTE imaging was increased from -7.3 for the magnitude images to 57.4 for the phase images. The preliminary results suggest that the IR-UTE sequence allows simultaneous magnitude and phase imaging of myelin in vitro and in vivo.
authors.affiliation: Department of Radiology, University of California, San Diego, United States; Ningbo Jansen NMR Technology Co., Ltd., Cixi, Zhejiang Province, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: He
authors.affiliation: Department of Radiology, University of California, San Diego, United States.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Radiology, University of California, San Diego, United States.
authors.forename: Shujuan
authors.initials: S
authors.lastname: Fan
authors.affiliation: Department of Radiology, University of California, San Diego, United States.
authors.forename: Hongda
authors.initials: H
authors.lastname: Shao
authors.affiliation: Department of Radiology, University of California, San Diego, United States.
authors.forename: Vipul
authors.initials: V
authors.lastname: Sheth
authors.affiliation: Department of Radiology, University of California, San Diego, United States.
authors.forename: Graeme M
authors.initials: GM
authors.lastname: Bydder
authors.affiliation: Department of Radiology, University of California, San Diego, United States. Electronic address: jiangdu@ucsd.edu.
authors.forename: Jiang
authors.initials: J
authors.lastname: Du
mesh_terms: D000328:Adult; D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging*; D001931:Brain Mapping; D002417:Cattle; D003287:Contrast Media; D005240:Feasibility Studies; D066128:Gray Matter; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D004676:Myelin Basic Protein; D009186:Myelin Sheath / Q000737:chemistry*; D019047:Phantoms, Imaging; D012408:Rubber; D059629:Signal-To-Noise Ratio; D014867:Water; D066127:White Matter
chemical_list: D003287:Contrast Media; C499048:MBP protein, human; D004676:Myelin Basic Protein; D014867:Water; D012408:Rubber
keywords: IR-UTE; Magnitude; Myelin; Phase; T2*; UTE; White matter