title: Impact of Yttrium-90 Microsphere Density, Flow Dynamics, and Administration Technique on Spatial Distribution: Analysis Using an In Vitro Model.
abstract: OBJECTIVE
  To investigate material density, flow, and viscosity effects on microsphere distribution within an in vitro model designed to simulate hepatic arteries.
  
  
  METHODS
  A vascular flow model was used to compare distribution of glass and resin surrogates in a clinically derived flow range (60-120 mL/min). Blood-mimicking fluid (BMF) composed of glycerol and water (20%-50% vol/vol) was used to simulate a range of blood viscosities. Microsphere distribution was quantified gravimetrically, and injectate solution was dyed to enable quantification by UV spectrophotometry. Microsphere injection rate (5-30 mL/min) and the influence of contrast agent dilution of injection solution (0%-60% vol/vol) were also investigated.
  
  
  RESULTS
  No significant differences in behavior were observed between the glass and resin surrogate materials under any tested flow conditions (P = .182; n = 144 injections). Microspheres tend to align more consistently with the saline injection solution (r2 = 0.5712; n = 144) compared with total BMF flow distribution (r2 = 0.0104; n = 144). The most predictable injectate distribution (ie, greatest alignment with BMF flow, < 5% variation) was demonstrated with > 10-mL/min injection rates of pure saline solution, although < 20% variation with glass microsphere distribution was observed with injection solution containing as much as 30% contrast medium when injected at > 20 mL/min.
  
  
  CONCLUSIONS
  Glass and resin yttrium-90 surrogates demonstrated similar distribution in a range of clinically relevant flow conditions, suggesting that microsphere density does not have a significant influence on microsphere distribution. Injection parameters that enhanced the mixing of the spheres with the BMF resulted in the most predictable distribution.
authors.affiliation: Department of Engineering and the Environment, University of Southampton, Highfield, United Kingdom; Biocompatibles UK, Lakeview, Riverside Way, Watchmoor Park, Camberley, United Kingdom GU15 3YL. Electronic address: marcus.caine@btgplc.com.
authors.forename: Marcus
authors.initials: M
authors.lastname: Caine
authors.affiliation: Biocompatibles UK, Lakeview, Riverside Way, Watchmoor Park, Camberley, United Kingdom GU15 3YL.
authors.forename: Michael S
authors.initials: MS
authors.lastname: McCafferty
authors.affiliation: BTG International Canada, Ottawa, Ontario, Canada.
authors.forename: Scott
authors.initials: S
authors.lastname: McGhee
authors.affiliation: Biocompatibles UK, Lakeview, Riverside Way, Watchmoor Park, Camberley, United Kingdom GU15 3YL.
authors.forename: Pedro
authors.initials: P
authors.lastname: Garcia
authors.affiliation: BTG International Canada, Ottawa, Ontario, Canada.
authors.forename: Wayne M
authors.initials: WM
authors.lastname: Mullett
authors.affiliation: Department of Engineering and the Environment, University of Southampton, Highfield, United Kingdom.
authors.forename: Xunli
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Engineering and the Environment, University of Southampton, Highfield, United Kingdom.
authors.forename: Martyn
authors.initials: M
authors.lastname: Hill
authors.affiliation: Biocompatibles, West Conshohocken, Pennsylvania.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Dreher
authors.affiliation: Biocompatibles UK, Lakeview, Riverside Way, Watchmoor Park, Camberley, United Kingdom GU15 3YL.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Lewis
mesh_terms: D001783:Blood Flow Velocity; D001809:Blood Viscosity; D004621:Embolization, Therapeutic / Q000379:methods*; D005898:Glass / Q000737:chemistry*; D005990:Glycerol / Q000737:chemistry; D006499:Hepatic Artery / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008102:Liver Circulation; D008113:Liver Neoplasms / Q000098:blood supply / Q000628:therapy*; D008863:Microspheres; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D019275:Radiopharmaceuticals / Q000008:administration & dosage*; D012039:Regional Blood Flow; D016628:Replica Techniques; D012117:Resins, Synthetic / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D015021:Yttrium Radioisotopes / Q000008:administration & dosage*
chemical_list: D019275:Radiopharmaceuticals; D012117:Resins, Synthetic; D015021:Yttrium Radioisotopes; D014867:Water; D005990:Glycerol