title: Negatively charged superparamagnetic iron oxide nanoparticles: a new blood-pooling magnetic resonance contrast agent.
abstract: OBJECTIVE
  Our purpose was to investigate the utility of superparamagnetic iron-oxide nanoparticles (SPIO) as a blood-pooling contrast agent at magnetic resonance imaging (MRI).
  
  
  METHODS
  We studied four contrast agents: carboxymethyl-diethylaminoethyl dextran magnetite SPIO (CMEADM-S, diameter 54 nm), negatively charged CMEADM ultrasmall SPIO (CMEADM-U, 32 nm), alkali-treated dextran magnetite SPIO (ATDM-S, 55 nm), and ATDM ultrasmall SPIO (ATDM-U, 28 nm) carrying a neutral charge. Each contrast agent (80 μmol/kg) was injected intraperitoneally into apolipoprotein E (apoE) mice and the tissue iron concentration was measured 30-, 60-, 180-, and 300-min later by nuclear MR. For MR angiographic (MRA) evaluation, we injected the agents into the auricular vein of four groups of 15 rabbits. Immediately and 30-, 60-, 180-, and 300-min later, three rabbits from each group were subjected to MRI. The organ/background signal ratio (SR) was calculated. Statistical analyses were performed with Tukey's honestly significant difference (HSD) test.
  
  
  RESULTS
  At 60 and 180 min, blood-iron concentration of CMEADM-U was significantly different from other contrast agents. In the abdominal aorta and inferior vena cava, SR of CMEADM-U was higher at 180 and 300 min than of the other contrast agents. In the thoracic aorta, there was no difference in SR at 300 min between CMEADM-U and CMEADM-S.
  
  
  CONCLUSIONS
  Negatively charged SPIO nanoparticles may be useful as a blood-pooling contrast agent.
authors.affiliation: Department of Radiology, Shiga University of Medical Science, Tsukinowaco, Seta, Otsu, Shiga 520-2192, Japan. r34nitta@belle.shiga-med.ac.jp
authors.forename: Norihisa
authors.initials: N
authors.lastname: Nitta
authors.forename: Keiko
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Akinaga
authors.initials: A
authors.lastname: Sonoda
authors.forename: Shinichi
authors.initials: S
authors.lastname: Ota
authors.forename: Noritoshi
authors.initials: N
authors.lastname: Ushio
authors.forename: Masashi
authors.initials: M
authors.lastname: Takahashi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Murata
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nohara
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000737:chemistry; D008422:Materials Testing; D051379:Mice; D011817:Rabbits
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; C000499:ferric oxide