title: Magnetic resonance imaging diagnosis of metastatic lymph nodes in a rabbit model: efficacy of PJY10, a new ultrasmall superparamagnetic iron oxide agent, with monodisperse iron oxide core and multiple-interaction ligands.
abstract: BACKGROUND
  Accurate diagnosis of lymph node metastasis is crucial in treatment planning for cancer patients. Despite the use of various parameters, making correct diagnosis of a small metastatic or a hyperplastic benign node is still a challenge. In this study, we evaluated the feasibility of detecting lymph node metastasis using a new ultrasmall superparamagnetic iron oxide particle, PJY10, in a rabbit model.
  
  
  METHODS
  To make metastatic and benign lymph nodes, either VX2 carcinoma or fecal material suspension was inoculated into thighs of 56 rabbits three weeks or three days before magnetic resonance (MR) imaging, respectively. T2*-weighted 3T MR imaging was performed before and 24 hours after PJY10 injection (5.2 [n = 15], 7.8 [n = 17], and 10.4 [n = 24] mg Fe/kg). MR images were correlated with pathologic results to calculate sensitivity and specificity. Quantitative analysis of the signal intensity (SI)--number of voxels[low] (the fraction of the number of voxels with the normalized SI on the postcontrast image lower than that on the precontrast image) and mean SI ratio--was also performed for each lymph node.
  
  
  RESULTS
  Sensitivities were 100% at all three dosages, whereas specificity increased with increasing dosage (89% at 10.4 mg Fe/kg). The benign nodes had a significantly higher number of voxels[low] and a lower mean SI ratio than the metastatic nodes at the dosage of 10.4 mg Fe/kg (P<.001). Az values were 0.905 for the number of voxels[low] and 0.952 for the mean SI ratio. The number of voxels[low] (P = .019) and the mean SI ratio (P=.034) had significant correlations with the histopathologic area ratio of metastatic foci in the metastatic nodes at 10.4 mg Fe/kg.
  
  
  CONCLUSIONS
  PJY10 enabled clear demonstration of lymph node metastasis with high sensitivity and specificity at its optimal dosage of 10.4 mg Fe/kg.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Roh-Eul
authors.initials: RE
authors.lastname: Yoo
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea; Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul National University, Seoul, Korea; School of Chemical and Biological Engineering, Seoul National University, Seoul, Korea.
authors.forename: Seung Hong
authors.initials: SH
authors.lastname: Choi
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea; Department of Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Hye Rim
authors.initials: HR
authors.lastname: Cho
authors.affiliation: Research & Development Center, Hanwha Chemical Corp., Daejeon, Yuseong-gu, Korea.
authors.forename: Bong-Sik
authors.initials: BS
authors.lastname: Jeon
authors.affiliation: Research & Development Center, Hanwha Chemical Corp., Daejeon, Yuseong-gu, Korea.
authors.forename: Eunbyul
authors.initials: E
authors.lastname: Kwon
authors.affiliation: Research & Development Center, Hanwha Chemical Corp., Daejeon, Yuseong-gu, Korea.
authors.forename: Eung-Gyu
authors.initials: EG
authors.lastname: Kim
authors.affiliation: Research & Development Center, Hanwha Chemical Corp., Daejeon, Yuseong-gu, Korea.
authors.forename: Juyoung
authors.initials: J
authors.lastname: Park
authors.affiliation: Research & Development Center, Hanwha Chemical Corp., Daejeon, Yuseong-gu, Korea.
authors.forename: Wan-Jae
authors.initials: WJ
authors.lastname: Myeong
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jae-Kyung
authors.initials: JK
authors.lastname: Won
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Yun-Sang
authors.initials: YS
authors.lastname: Lee
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea; Department of Radiology, Boramae Medical Center, Seoul, Korea.
authors.forename: Sun-Won
authors.initials: SW
authors.lastname: Park
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Sohn
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry; D004195:Disease Models, Animal; D005290:Ferric Compounds / Q000737:chemistry*; D006801:Humans; D007089:Image Enhancement; D008024:Ligands; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology; D008207:Lymphatic Metastasis / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry; D011817:Rabbits; D011859:Radiography
chemical_list: D003287:Contrast Media; D003911:Dextrans; D005290:Ferric Compounds; D008024:Ligands; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10; C000499:ferric oxide