title: Experimental system to detect a labeled cell monolayer in a microfluidic environment.
abstract: OBJECTIVE
  To investigate the feasibility of detecting a living cell monolayer labeled with gadoterate (Gd-DOTA) in a microfluidic environment, by micromagnetic resonance imaging (MRI) in a 2.35T small-animal system. The development of new targeted contrast agents (CAs) requires proof-of-concept studies in order to establish the detectability of the CA and to predict the role of biodistribution in its uptake mechanisms. A promising approach is to carefully mimic the in vivo pharmacokinetic context with reduced experimental complexity compared to in vivo situations.
  
  
  METHODS
  A dedicated experimental system was built by combining a microfluidic slide and a radiofrequency probe based on a 6 mm diameter multiturn transmission-line resonator. Adherent KB cells were incubated with different concentrations of Gd. MRI data were acquired at 2.35T with a 3D gradient echo and a resolution of 12.4 μm perpendicular to the cell layer. The longitudinal relaxation rate, R1 , was measured as a function of the amount of Gd internalized by the cells.
  
  
  RESULTS
  R1 measurements for different Gd concentrations per cell were performed using data with an signal-to-noise ratio (SNR) of 100. Relaxation-rate variations ΔR1 of 0.035 s(-1) were measured. A quenching effect was observed at Gd concentrations above 20 fmol/cell.
  
  
  CONCLUSIONS
  Our results suggest that this dedicated experimental system is suitable for specifically assessing new high-relaxivity targeted CAs under real-time uptake conditions.
authors: IR4M, UMR 8081, Orsay, France.
authors: Nicolas
authors: N
authors: Gargam
authors: IR4M, UMR 8081, Orsay, France.
authors: Luc
authors: L
authors: Darrasse
authors: IR4M, UMR 8081, Orsay, France.
authors: Jean-Sebastien
authors: JS
authors: Raynaud
authors: IR4M, UMR 8081, Orsay, France.
authors: Jean-Christoph
authors: JC
authors: Ginefri
authors: IR4M, UMR 8081, Orsay, France.
authors: Philippe
authors: P
authors: Robert
authors: IR4M, UMR 8081, Orsay, France.
authors: Marie
authors: M
authors: Poirier-Quinot
mesh_terms: D000818:Animals; D058948:Cell Tracking / Q000379:methods* / Q000662:veterinary; D003287:Contrast Media / Q000493:pharmacokinetics; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D006571:Heterocyclic Compounds / Q000493:pharmacokinetics*; D006801:Humans; D007624:KB Cells; D056656:Lab-On-A-Chip Devices / Q000662:veterinary*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000662:veterinary; D009374:Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology*; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D013194:Staining and Labeling; D059016:Tumor Microenvironment
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate
keywords: MR contrast agent; cell monolayer; microfluidic; multiturn transmission line resonator