99.1% EMBOLIZATION EFFICIENCY

Background: Despite the tremendous advances made with embolic agents and imaging, the actual delivery of embolics is fairly undeveloped, lacks control, and has significant risks for non-target embolization. A major challenge is that current commercially available microcatheters lack precision and freely allows the reflux of the beads/ backward into healthy tissue. The goal of this study was to demonstrate in a porcine model, that reflux during embolotherapy can be quantified (infusion efficiency) and non-target embolization can be reduced utilizing an anti-reflux microcatheter.

Methods: In six swine, renal arteries embolization was performed utilizing radiopaque visible tantalum beads (mean size 44 um) at a concentration of 1gm/20cc. Second order left renal arteries (N=3) underwent embolization with a standard 4fr diagnostic catheter as control. Second order right renal artery (N=3) underwent embolization with a 3fr anti-reflux microcatheter as the experimental arm. After embolization, kidneys were explanted and underwent micro CT imaging. 3D volumetric/multiplanar MIP imaging of the kidneys were performed to assess the vascular distribution of tantalum beads. DICOM data was analyzed using ImageJ (NIH, Bethesda, MD) using a threshold to create binary images. The number of positive values in a region of interest (ROI) in the target embolized tissue (upper pole or lower pole) and the non-target tissue was then determined. Infusion efficiency was calculated as: ROI (target pole)/ (ROI (target pole + ROI (nontarget pole)). Infusion efficiency was calculated in two orthogonal planes (coronal and sagittal). Statistical analysis was performed with paired T-test analysis.

Results: All renal arteries underwent successful embolization with tantalum beads. Micro CT provided high-resolution visualization of the renal parenchyma at 50 um resolution. Tantalum beads were readily visible. In control renal arteries, a standard 4fr catheter had an infusion efficiency of 70.8% (+/-4.4%). In experimental renal arteries with an antireflux microcatheter, infusion efficiency increased to 99.1 % (+/-1.2%) and reached statistical significance (p=. 005). See Figure 1.

Conclusions: Infusion efficiency can be used to quantify reflux during embolotherapy with radiopaque beads. There is a statistically significant increase in infusion efficiency (reduction in reflux) with an anti-reflux microcatheter.

K. Hong, J. Chomas, D. Kraitchman, B. Naglreiter, A. Arepally. Quantification and reduction of reflux during embolotherapy using micro CT and tantalum beads with ex-vivo analysis. Presented at the World Congress of Interventional Oncology, June 2011. Data on file at Surefire Medical, Inc.