title: Positive contrast visualization of iron oxide-labeled stem cells using inversion-recovery with ON-resonant water suppression (IRON).
abstract: In proton magnetic resonance imaging (MRI) metallic substances lead to magnetic field distortions that often result in signal voids in the adjacent anatomic structures. Thus, metallic objects and superparamagnetic iron oxide (SPIO)-labeled cells appear as hypointense artifacts that obscure the underlying anatomy. The ability to illuminate these structures with positive contrast would enhance noninvasive MR tracking of cellular therapeutics. Therefore, an MRI methodology that selectively highlights areas of metallic objects has been developed. Inversion-recovery with ON-resonant water suppression (IRON) employs inversion of the magnetization in conjunction with a spectrally-selective on-resonant saturation prepulse. If imaging is performed after these prepulses, positive signal is obtained from off-resonant protons in close proximity to the metallic objects. The first successful use of IRON to produce positive contrast in areas of metallic spheres and SPIO-labeled stem cells in vitro and in vivo is presented.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA. mstuber@mri.jhu.edu
authors.forename: Matthias
authors.initials: M
authors.lastname: Stuber
authors.forename: Wesley D
authors.initials: WD
authors.lastname: Gilson
authors.forename: Michael
authors.initials: M
authors.lastname: Schär
authors.forename: Dorota A
authors.initials: DA
authors.lastname: Kedziorek
authors.forename: Lawrence V
authors.initials: LV
authors.lastname: Hofmann
authors.forename: Saurabh
authors.initials: S
authors.lastname: Shah
authors.forename: Evert-Jan
authors.initials: EJ
authors.lastname: Vonken
authors.forename: Jeff W M
authors.initials: JW
authors.lastname: Bulte
authors.forename: Dara L
authors.initials: DL
authors.lastname: Kraitchman
mesh_terms: D003287:Contrast Media; D005290:Ferric Compounds / Q000737:chemistry*; D013234:Stem Cells / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D014867:Water; C000499:ferric oxide