title: Multimodal visibility (radiography, computed tomography, and magnetic resonance imaging) of microspheres for transarterial embolization tested in porcine kidneys.
abstract: OBJECTIVE
  The objective of this study was to test multimodal visibility (radiography, computed tomography [CT], and magnetic resonance imaging [MRI]) of microspheres for transarterial embolization in porcine kidneys.
  
  
  METHODS
  Currently available embolization particles (microspheres) were modified. A dense x-ray material (barium sulfate) was added to create visibility for radiography and CT. A magnetic substance (iron oxide) was additionally added to create visibility for MRI. This chemical modification was performed for particles with sizes of 100 ± 25 and 700 ± 50 μm. Three different prototypes per size class (samples A, B, and C) resulted, each with a different degree of barium sulfate but with the same degree of iron oxide. The currently available embolization particles with sizes of 100 ± 25 and 700 ± 50 μm were used as controls (sample control). Eight renal arteries of 4 pigs were embolized. Study end points were size distribution evaluated in vitro as well as qualitative and quantitative particle visibility evaluated in vivo.
  
  
  RESULTS
  The size distribution of the particles with a size of 100 ± 25 μm was between 96 ± 11 μm for sample A and 102 ± 13 μm for the sample control without significant differences (n.s.). The size distribution of the particles with a size of 700 ± 50 μm was between 691 ± 20 μm for sample A and 716 ± 34 μm for sample C without significant differences (n.s.). For radiography, the particles with sizes of 100 ± 25 and 700 ± 50 μm for samples A, B, and C were definitely visible during the embolization. The sample control was definitely not visible. For CT and MRI (T1-weighted [T1w] and T2-weighted [T2w]), the particles with sizes of 100 ± 25 and 700 ± 50 μm for samples A, B, and C were definitely visible after the embolization. The sample control was definitely not visible. For CT, the signal-to-noise ratio for samples A, B, and C increased significantly after the embolization (eg, sample A, particles with a size of 100 ± 25 μm: 66.5% ± 23.7%, P < 0.05). The signal-to-noise ratio for the sample control did not change after the embolization (eg, sample control, particles with a size of 700 ± 25 μm: -0.2% ± 15.2%, n.s.). For MRI (T1w and T2w), the signal-to-noise ratio for samples A, B, and C decreased significantly after the embolization (eg, sample B, particles with a size of 700 ± 50 μm, T1w: -72.9% ± 6.6%; P < 0.05). The signal-to-noise ratio for the sample control did not change after the embolization (eg, sample control, particles with a size of 100 ± 25 μm, T2w: 6.2% ± 16.1%, n.s.).
  
  
  CONCLUSIONS
  In this study, the chemical modification of the currently available microspheres for transarterial embolization resulted in a size distribution comparable with the currently available microspheres and created multimodal visibility for radiography, CT, and MRI.
authors: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany. christof.sommer@med.uni-heidelberg.de
authors: Christof M
authors: CM
authors: Sommer
authors: Ulrike
authors: U
authors: Stampfl
authors: Nadine
authors: N
authors: Bellemann
authors: Maria
authors: M
authors: Holzschuh
authors: Alexander
authors: A
authors: Kueller
authors: Jaques
authors: J
authors: Bluemmel
authors: Tobias
authors: T
authors: Gehrig
authors: Maxym
authors: M
authors: Shevchenko
authors: Hannes G
authors: HG
authors: Kenngott
authors: Hans U
authors: HU
authors: Kauczor
authors: Philippe L
authors: PL
authors: Pereira
authors: Boris A
authors: BA
authors: Radeleff
mesh_terms: D000818:Animals; D001466:Barium Sulfate / Q000008:administration & dosage; D003287:Contrast Media / Q000008:administration & dosage; D003911:Dextrans / Q000008:administration & dosage; D004621:Embolization, Therapeutic / Q000379:methods*; D005260:Female; D007668:Kidney; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000008:administration & dosage; D008863:Microspheres; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D001466:Barium Sulfate; C065507:ferumoxides