title: Ultrashort echo time (UTE) magnetic resonance imaging of the short T2 components in white matter of the brain using a clinical 3T scanner.
abstract: White matter of the brain contains a majority of long T2 components as well as a minority of short T2 components. These are not detectable using clinical magnetic resonance imaging (MRI) sequences with conventional echo times (TEs). In this study we used ultrashort echo time (UTE) sequences to investigate the ultrashort T2 components in white matter of the brain and quantify their T2*s and relative proton densities (RPDs) (relative to water with a proton density of 100%) using a clinical whole body 3T scanner. An adiabatic inversion recovery prepared dual echo UTE (IR-dUTE) sequence was used for morphological imaging of the ultrashort T2 components in white matter. IR-dUTE acquisitions at a constant TR of 1000 ms and a series of TIs were performed to determine the optimal TI which corresponded to the minimum signal to noise ratio (SNR) in white matter of the brain on the second echo image. T2*s of the ultrashort T2 components were quantified using mono-exponential decay fitting of the IR-dUTE signal at a series of TEs. RPD was quantified by comparing IR-dUTE signal of the ultrashort T2 components with that of a rubber phantom. Nine healthy volunteers were studied. The IR-dUTE sequence provided excellent image contrast for the ultrashort T2 components in white matter of the brain with a mean signal to noise ratio of 18.7 ± 3.7 and a contrast to noise ratio of 14.6 ± 2.4 between the ultrashort T2 white matter and gray matter in a 4.4 min scan time with a nominal voxel size of 1.25 × 1.25 × 5.0mm(3). On average a T2* value of 0.42 ± 0.08 ms and a RPD of 4.05 ± 0.88% were demonstrated for the ultrashort T2 components in white matter of the brain of healthy volunteers at 3T.
authors.affiliation: Department of Radiology, University of California, San Diego, USA. Electronic address: jiangdu@ucsd.edu.
authors.forename: Jiang
authors.initials: J
authors.lastname: Du
authors.affiliation: Department of Radiology, University of California, San Diego, USA; Department of Radiology, China-Japan Friendship Hospital, Beijing, China.
authors.forename: Guolin
authors.initials: G
authors.lastname: Ma
authors.affiliation: Department of Radiology, University of California, San Diego, USA; Department of Radiology, Huadong Hospital, Fudan University, Shanghai, China.
authors.forename: Shihong
authors.initials: S
authors.lastname: Li
authors.affiliation: Global Applied Science Laboratory, GE Healthcare, San Diego, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Carl
authors.affiliation: Department of Radiology, University of California, San Diego, USA.
authors.forename: Nikolaus M
authors.initials: NM
authors.lastname: Szeverenyi
authors.affiliation: Department of Pathology, University of California, San Diego, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: VandenBerg
authors.affiliation: Department of Neurosciences, University of California, San Diego, USA.
authors.forename: Jody
authors.initials: J
authors.lastname: Corey-Bloom
authors.affiliation: Department of Radiology, University of California, San Diego, USA.
authors.forename: Graeme M
authors.initials: GM
authors.lastname: Bydder
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain; D001931:Brain Mapping / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated
keywords: Adiabatic IR; Proton density; T2*; Ultrashort T2; Ultrashort echo time; White matter