title: In vivo MRI discrimination between live and lysed iron-labelled cells using balanced steady state free precession.
abstract: OBJECTIVE
  The goal of this study was to evaluate the ability of balanced steady state free precession (b-SSFP) magnetic resonance imaging sequence to distinguish between live and lysed iron-labelled cells.
  
  
  METHODS
  Human breast cancer cells were labelled with iron oxide nanoparticles. Cells were lysed using sonication. Imaging was performed at 3 T. The timing parameters for b-SSFP and the number of iron-labelled cells in samples were varied to optimise the b-SSFP signal difference between live and lysed iron-labelled cell samples. For in vivo experiments, cells were mixed with Matrigel and implanted into nude mice. Three mice implanted with live labelled cancer cells were irradiated to validate this method.
  
  
  RESULTS
  Lysed iron-labelled cells have a significantly higher signal compared with live, intact iron-labelled cells in bSSFP images. The contrast between live and dead cells can be maximised by careful optimisation of timing parameters. A change in the b-SSFP signal was measured 6 days after irradiation, reflecting cell death in vivo. Histology confirmed the presence of dead cells in the implant.
  
  
  CONCLUSIONS
  Our results show that the b-SSFP sequence can be optimised to allow for the discrimination of live iron-labelled cells and lysed iron-labelled cells in vitro and in vivo.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, 100 Perth Drive, Rm1200B, London, ON, Canada.
authors.forename: E J
authors.initials: EJ
authors.lastname: Ribot
authors.forename: P J
authors.initials: PJ
authors.lastname: Foster
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology*; D002458:Cell Fractionation / Q000379:methods*; D045744:Cell Line, Tumor; D058948:Cell Tracking / Q000379:methods*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007501:Iron; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008819:Mice, Nude; D057054:Molecular Imaging / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D003287:Contrast Media; D007501:Iron