Quantification and reduction of reflux during embolotherapy using an antireflux catheter and tantalum microspheres: Ex vivo analysis

Purpose: To demonstrate in a porcine model that reflux during embolotherapy can be relatively quantified (ie, as embolization efficiency) and that nontarget embolization can be eliminated by using an antireflux microcatheter. Materials and Methods: Renal artery embolization was performed with radiopaque tantalum microspheres (concentration of 1 g/20 mL) in three swine. Second-order right renal arteries (n = 3) underwent embolization with a 3-F antireflux catheter, and second-order left renal arteries (n = 3) underwent embolization with a 4-F end-hole catheter as a control. After embolization, kidneys were explanted and underwent micro-computed tomographic (microCT) imaging. Three-dimensional volumetric and multiplanar imaging of the kidneys was performed to assess vascular distribution. Digital Imaging and Communications in Medicine data were analyzed, with a threshold algorithm used to create binary images. The number of positive values in a region of interest in the target embolized tissue (upper pole or lower pole) and the nontarget adjacent tissue was determined, and embolization efficiency was calculated. Wilcoxon rank-sum statistical analysis was performed to compare nontarget embolization between infusion catheters. Results: All renal arteries underwent successful embolization with tantalum microspheres, with 20 mL (1 g) administered in all dose deliveries. MicroCT provided high-resolution visualization of the renal parenchyma at 70-μm resolution. In control renal arteries, a standard 4-F end-hole catheter had an embolization efficiency of 72%±13. In experimental renal arteries, the antireflux microcatheter had an embolization efficiency of 99.9%±1.0 (P<. 05). Conclusions: A significant decrease in nontarget embolization (ie, reduction in reflux) was possible with an antireflux microcatheter compared with a conventional end-hole catheter.