Figure 1.

Images of a clean and one Onyx 18 embolized in vitro model (A) as well as a schematic illustration of its structure (B). The image on the right of the upper row (C) illustrates one Onyx embolized in vitro model in fluoroscopy and an exemplary placement of the applied regions of interest (ROI; white: ROI along the 1.5 mm sector; black: ROI drawn on the similar level on the non-cavity part of the in vitro model). Representative fluoroscopic images of the in vitro models embolized with different liquid embolic agents as well as contrast medium and saline, both serving a reference standard, are demonstrated in the lower row (D). The window width was set at 4095 density units (DU) and the window level at 2047 DU. Please note the radiopaque material at the upper end of the different PHIL formulations and NBCA/iodized oil embolized models which is of artificial character and had no influence on the present results. Yellow arrow: sector with a diameter of 0.5 mm to verify the success of the embolization procedure; red arrows: sectors of interest for quantitative and qualitative analysis with a diameter of 2.0 mm, 1.5 mm, and 1.0 mm; green arrow: sector with a diameter of 21 mm for placement of a 5 French sheath introducer. Please note the used microcatheter in the saline filled in vitro model. LV, low viscosity; NBCA, n-butyl cyanoacrylate; PHIL, precipitating hydrophobic injectable liquid.