title: Magnetic resonance imaging of myelin using ultrashort Echo time (UTE) pulse sequences: Phantom, specimen, volunteer and multiple sclerosis patient studies.
abstract: Clinical magnetic resonance imaging of multiple sclerosis (MS) has focused on indirect imaging of myelin in white matter by detecting signal from protons in the water associated with myelin. Here we show that protons in myelin can be directly imaged using ultrashort echo time (UTE) free induction decay (FID) and imaging sequences on a clinical 3T MR scanner. An adiabatic inversion recovery UTE (IR-UTE) sequence was used to detect signal from myelin and simultaneously suppress signal from water protons. Validation studies were performed on myelin lipid and myelin basic protein (MBP) phantoms in the forms of lyophilized powders as well as suspensions in D2O and H2O. IR-UTE sequences were then used to image MS brain specimens, healthy volunteers, and patients. The T2* of myelin was measured using a UTE FID sequence, as well as UTE and IR-UTE sequences at different TEs. T2* values of ~110-330μs were measured with UTE FID, as well as with UTE and IR-UTE sequences for myelin powders, myelin-D2O and myelin-H2O phantoms, consistent with selective imaging of myelin protons with IR-UTE sequences. Our studies showed myelin selective imaging of white matter in the brains in vitro and in vivo. Complete or partial signal loss was observed in specimens in areas of the brain with histopathologic evidence of myelin loss, and in the brain of patients with MS.
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: Hongda
authors.initials: H
authors.lastname: Shao
authors.affiliation: Department of Radiology, University of California, San Diego, United States.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Pathology, University of California, San Francisco, United States.
authors.forename: Scott
authors.initials: S
authors.lastname: Vandenberg
authors.affiliation: Department of Neurosciences, University of California, San Diego, United States.
authors.forename: Jody
authors.initials: J
authors.lastname: Corey-Bloom
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; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D009186:Myelin Sheath / Q000378:metabolism*; D019047:Phantoms, Imaging; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D066127:White Matter / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology
chemical_list: D015415:Biomarkers
keywords: MRI; Myelin; Myelin basic protein; Myelin lipid; UTE