title: In vivo identification of sentinel lymph nodes using MRI and size-controlled and monodispersed magnetite nanoparticles.
abstract: OBJECTIVE
  To develop a sentinel lymph node (SN) identification method using accurately synthesized magnetic nanoparticles (MNPs), as an enhanced specific SN tracer in combination with magnetic resonance imaging (MRI) in intact rodent and SN metastasis models.
  
  
  METHODS
  Three sizes of MNPs were originally synthesized. We developed an experimental rat SN model, with brachial lymph nodes (Br) as the SN and the axillary lymph node (Ax) as the second lymph node, and injection of MNPs via the front paw. SN detectability was evaluated in vivo using T1 -weighted MR images after injection of the synthesized MNPs, and the amount of iron in the Br and in the Ax was assessed using inductively coupled plasma optical emission spectrometry.
  
  
  RESULTS
  The highest ratios of the amount of iron in the Br versus the Ax were 3.1 and 3.3, using 20-nm MNPs after 2- and 24-hour injections. The appropriate dose and particle diameter for MRI detection was optimized, and the SN was optimally distinguished in the normal and metastatic rat models using MRI after a 0.4 mg/kg 20-nm MNP injection.
  
  
  CONCLUSIONS
  We developed and optimized a useful SN identification method using MRI in rodent models.
authors.affiliation: Department of Surgery, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Iida
authors.forename: Kensuke
authors.initials: K
authors.lastname: Imai
authors.forename: Sachiko
authors.initials: S
authors.lastname: Matsuda
authors.forename: Osamu
authors.initials: O
authors.lastname: Itano
authors.forename: Mamoru
authors.initials: M
authors.lastname: Hatakeyama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sakamoto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kokuryo
authors.forename: Koji
authors.initials: K
authors.lastname: Okabayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Endo
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ishii
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Ichio
authors.initials: I
authors.lastname: Aoki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Handa
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kitagawa
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000473:pathology* / Q000556:secondary*; D003287:Contrast Media / Q000009:adverse effects; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000009:adverse effects / Q000648:ultrastructure*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010316:Particle Size; D051381:Rats; D011916:Rats, Inbred F344; D011923:Rats, Nude; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000379:methods
chemical_list: D003287:Contrast Media; D058185:Magnetite Nanoparticles
keywords: MRI; detection; magnetic nanoparticles; sentinel lymph node