title: Atherosclerotic imaging using 4 types of superparamagnetic iron oxides: new possibilities for mannan-coated particles.
abstract: OBJECTIVE
  We used magnetic resonance imaging (MRI) and histologic techniques to compare the uptake by the rabbit atherosclerotic wall of 4 types of superparamagnetic iron oxide (SPIO) particles, i.e. SPIO, mannan-coated SPIO (M-SPIO), ultrasmall SPIO (USPIO), and mannan-coated USPIO (M-USPIO).
  
  
  METHODS
  All experimental protocols were approved by our institutional animal experimentation committee. We intravenously injected 12 Watanabe heritable hyperlipidemic rabbits with one of the 4 types of SPIO (0.8 mmol Fe/kg). Two other rabbits served as the control. The rabbits underwent in vivo contrast-enhanced magnetic resonance angiography (MRA) before- and 5 days after these injections; excised aortae were subjected to in vitro MRI. In the in vivo and in vitro studies we assessed the signal intensity of the vessels at identical regions of interest (ROI) and calculated the signal-to-noise ratio (SNR). For histologic assessment we evaluated the iron-positive regions in Prussian blue-stained specimens.
  
  
  RESULTS
  There were significant differences in iron-positive regions where M-USPIO>USPIO, M-SPIO>SPIO, USPIO>SPIO (p<0.05) but not between M-USPIO and M-SPIO. The difference between the pre- and post-injection SNR was significantly greater in rabbits treated with M-USPIO than USPIO and in rabbits injected with M-SPIO than SPIO (p<0.05). On in vitro MRI scans SNR tended to be lower in M-USPIO- and M-SPIO- than USPIO- and SPIO-treated rabbits (p<0.1).
  
  
  CONCLUSIONS
  Histologic and imaging analysis showed that mannan-coated SPIO and USPIO particles were taken up more readily by the atherosclerotic rabbit wall than uncoated SPIO and USPIO.
authors.affiliation: Department of Radiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192, Japan(1). Electronic address: keikot@belle.shiga-medac.jp.
authors.forename: Keiko
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Norihisa
authors.initials: N
authors.lastname: Nitta
authors.forename: Akinaga
authors.initials: A
authors.lastname: Sonoda
authors.forename: Hideji
authors.initials: H
authors.lastname: Otani
authors.forename: Masashi
authors.initials: M
authors.lastname: Takahashi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Murata
authors.forename: Masashi
authors.initials: M
authors.lastname: Shiomi
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tabata
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nohara
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000378:metabolism* / Q000473:pathology*; D003287:Contrast Media / Q000138:chemical synthesis / Q000493:pharmacokinetics; D003911:Dextrans / Q000737:chemistry / Q000493:pharmacokinetics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000737:chemistry; D008351:Mannans / Q000737:chemistry / Q000493:pharmacokinetics*; D053769:Nanocapsules / Q000737:chemistry / Q000648:ultrastructure; D010316:Particle Size; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D008351:Mannans; D053769:Nanocapsules; C097921:ferumoxtran-10
keywords: Atherosclerosis; Atherosclerotic plaques; Magnetic resonance imaging