PURPOSE: To perform in vitro and in vivo studies of radiopaque microbeads o
f polyacrylonitrile (PAN) hydrogel to evaluate their characteristics as emb
MATERIALS AND METHODS: PAN microbeads were analyzed in vitro for swelling i
n different concentrations of contrast material and saline solution and inj
ected through various microcatheters. In three nonsurvival swine, various o
rgans were embolized with PAN microbeads. In eight survival swine, the rete
mirabile was embolized with PAN microbeads or polyvinyl alcohol particles.
Follow-up angiograms were obtained regularly, and histopathologic analysis
was performed at 1 and 6 months.
RESULTS: The microbeads were black with a regular shape and smooth surface.
They were easily visible in the syringe and easy to inject through the mic
rocatheters. When wet, their diameters increased by 40%. The microbeads wer
e sufficiently radiopaque to be visible in all vascular territories. Vascul
ar occlusion was not permanent, and even when embolization was adequate, so
me revascularization was detected at 3 months. The microbeads were intact a
nd still radiopaque at 6 months. Histopathologic examination demonstrated v
ariable inflammatory reactions and foreign-body giant cell reaction and no
angionecrosis or hemorrhage.
CONCLUSION: Because PAN microbeads are biocompatible, radiopaque, and easy
to handle during embolization procedures, they have potential as a therapeu
tic embolic agent.