title: MR lymphography: study of a high-efficiency lymphotrophic agent.
abstract: OBJECTIVE
  To investigate the utility of a monocrystalline iron oxide nanoparticle (MION) as a contrast agent in magnetic resonance (MR) imaging of lymph nodes.
  
  
  METHODS
  Pharmacokinetic data were obtained in rats after intravenous, subcutaneous, and intraarterial injection of indium-111-MION-46. MR imaging was performed to determine optimal dosages and pulse sequences in rats. Models of lymph node metastasis in rabbits and lymph node hyperplasia in rats were used to demonstrate the efficacy of MION in differentiation of malignant and benign adenopathies.
  
  
  RESULTS
  Biokinetic data indicate that nodal accumulation occurs primarily after extravasation of agent into the interstitial space (slow component) and subsequent trapping by lymph node macrophages (fast component). Relatively low concentrations (15-25 mumol Fe per kilogram for peripheral nodes after intraarterial injection) decrease signal intensity of nodes at MR imaging.
  
  
  CONCLUSIONS
  Lymph node accumulation of MION-46 is high. Modification of injection techniques that alter capillary permeability allows use of systemically administered agent at doses as low as 15-25 mumol Fe per kilogram.
authors.affiliation: Department of Radiology, Massachusetts General Hospital-East, Charlestown 02129.
authors.forename: R
authors.initials: R
authors.lastname: Weissleder
authors.forename: J F
authors.initials: JF
authors.lastname: Heautot
authors.forename: B K
authors.initials: BK
authors.lastname: Schaffer
authors.forename: N
authors.initials: N
authors.lastname: Nossiff
authors.forename: M I
authors.initials: MI
authors.lastname: Papisov
authors.forename: A
authors.initials: A
authors.lastname: Bogdanov
authors.forename: T J
authors.initials: TJ
authors.lastname: Brady
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics; D052203:Ferrosoferric Oxide; D006965:Hyperplasia / Q000175:diagnosis; D007501:Iron / Q000493:pharmacokinetics; D008198:Lymph Nodes / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000175:diagnosis / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D010087:Oxides / Q000493:pharmacokinetics; D011817:Rabbits; D011877:Radionuclide Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D003287:Contrast Media; D010087:Oxides; D007501:Iron; D052203:Ferrosoferric Oxide