title: Optimization of ultrasmall superparamagnetic iron oxide (P904)-enhanced magnetic resonance imaging of lymph nodes: initial experience in a mouse model.
abstract: BACKGROUND
  P904 is a novel ultra-small superparamagnetic iron oxide (USPIO) contrast agent. This study was conducted to investigate the optimal dose of P904 for magnetic resonance imaging (MRI) of lymph nodes.
  
  
  METHODS
  T2*-weighted 3T MRI was performed in 14 normal mice before and 24 h after P904 injection at varying doses. Normalized signal intensity (nSI), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and contrast ratio (CR) were calculated to determine the optimal dose. MRI of the metastatic lymph node models (n=5) was acquired using the optimal dose and correlated with pathological results to calculate sensitivity and specificity. The mean SI ratio between pre- and postcontrast MRI was also calculated for each lymph node.
  
  
  RESULTS
  The mean nSI and SNR values on postcontrast images were significantly lower at 300 μmol Fe/kg than at 75 μmol Fe/kg (p<0.001). The mean CNR and CR values were significantly higher at 300 μmol Fe/kg than at the other two doses (p<0.05). At the optimal dose of 300 μmol Fe/kg, the mean SI ratio of benign lymph nodes was significantly lower than that of metastatic lymph nodes (p<0.001). The Az (areas under the receiver operating characteristic curves) value for diagnosing lymph node metastasis at the optimal dose was 0.97.
  
  
  CONCLUSIONS
  The optimal dose for P904-enhanced MRI of the lymph nodes was 300 μmol Fe/kg, which could be used for the diagnosis of lymph node metastasis.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Roh-Eul
authors.initials: RE
authors.lastname: Yoo
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea Department of Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hye Rim
authors.initials: HR
authors.lastname: Cho
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea Center for Nanoparticle Research, Institute for Basic Science, Seoul National University, Seoul, Republic of Korea School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea verocay@snuh.org.
authors.forename: Seung Hong
authors.initials: SH
authors.lastname: Choi
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jae-Kyung
authors.initials: JK
authors.lastname: Won
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Sohn
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000737:chemistry; D004195:Disease Models, Animal; D005290:Ferric Compounds; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000008:administration & dosage / Q000737:chemistry; D051379:Mice; D009369:Neoplasms / Q000175:diagnosis* / Q000473:pathology
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; C000499:ferric oxide
keywords: Animal study; MRI; P904; USPIO; lymph node metastasis; magnetic resonance imaging of lymph nodes; ultra-small superparamagnetic iron oxide particle