Distribution of iron oxide-containing Embosphere particles after transcatheter arterial embolization in an animal model of liver cancer: evaluation with MR imaging and implication for therapy.

PURPOSE: To test whether different-sized iron oxide-containing Embosphere (IOE) particles can be detected by dedicated magnetic resonance (MR) imaging when injected intraarterially in an animal model of liver cancer and whether their distribution could be accurately predicted by MR imaging before confirmation with histopathologic analysis.
MATERIALS AND METHODS: Twenty New Zealand White rabbits implanted with VX2 liver tumor were randomly assigned to undergo embolization with 100-300-microm particles (group S; n = 10) or 300-500-microm particles (group L; n = 10). Embolization was performed with the catheter placed in the proper hepatic artery. T2*-weighted multiplanar MR imaging was performed within 24 hours after the procedure to detect paramagnetic IOE susceptibility artifact. MR imaging interpretation parameters included presence of artifact in the artery and/or at the tumor bed. Hematoxylin and eosin- and Prussian blue-stained pathologic slides were also obtained and the presence of IOE was evaluated similarly.
RESULTS: The MR detectability rates for IOEs were 100% in both groups. Paramagnetic susceptibility IOE artifact inside the tumor was detected in 30% of group S animals. On pathologic analysis, IOE particles were detected inside the tumor in 70% of this group. IOEs in group L were found outside the tumor within the hepatic artery on MR imaging and histopathologic study (P < .05).
CONCLUSIONS: MR imaging readily detected IOE particles in an animal model of liver cancer regardless of the particle size. The smaller particles (100-300 microm) were delivered inside the tumor or in close proximity to the tumor margin, justifying their use for drug delivery or precise embolization.