Oomoo 25

Our method of creating patient-specific in vitro models of cerebral aneurysms has been previously described.^{14 (link)} Briefly, a 3D reconstruction of the vascular lumen was created by segmenting the images with Vascular Modeling Toolkit (http://www.vmtk.org) software. An acrylonitrile butadiene styrene model of the vessel lumen was created at 1:1 scale by a 3D printer and then cast in silicone rubber (OOMOO 25; Smooth-On, Macungie, Pennsylvania, USA). The acrylic model was then removed and this silicone mold was used to create an additional lumen model from casting wax (Freeman, Avon, Ohio, USA). The wax model was cast in a clear polyester resin (Clear-Lite; TAP Plastics, San Leandro, California, USA) and cured for 24 hours. Finally, the wax was melted away until only the final resin model of the aneurysm and parent vessel remained.
Models were then ‘treated’ by experienced neurointerventionalists. Each model was treated with the same endovascular devices (stents and coils) in the same sizes and sequence as the actual patients’ treatments. Every attempt was made to match the placement of these devices in vitro to the final angiographic conformation in vivo.

The cerebral aneurysm models were acquired from human subjects using 3D rotational angiography imaging during an endovascular treatment procedure. A 3D reconstruction of the vascular surface was created by segmenting the images with the software Vascular Modeling Toolkit (vmtk.org). The geometrical characteristics of the aneurysm models are summarized in table 2. CAD representations of the in vitro models used for fabrication are shown in Figure 2.
The models were extended at the inflow and outflow sections of 9.5 mm diameter to allow integration into the flow loop. A physical “positive” model made of acrylonitrile butadiene styrene (ABS) was created at 1:1 scale by a 3D printer. The ABS model was then cast in a silicone rubber (OOMOO 25, Smooth-On Inc., Macungie, PA). After the silicone cured, the ABS model was cut and removed from the silicone, leaving a “negative” model. The silicone mold was then used to create an additional “positive” model from casting wax (Freeman, Avon, Ohio). The wax model was finally cast in a clear polyester resin (Clear-Lite, TAP Plastics, San Leandro, CA) which cured for 24 hours. The wax was melted away leaving the final “negative” model of the aneurysm and parent vessel. A photograph of one of the completed physical models is shown in Figure 2(d), and photographs of the additional in vitro models are provided in the supplementary materials.

A mold of the heel tread was made at baseline and after each month of wear. The left and right heels were placed in a rectangular containment (92 mm × 76 mm × 28 mm) of silicone rubber compound (Smooth-On Inc.; Macungie, PA; Oomoo® 25) at an angle of 17° (Figure 3). The largest region of continuous wear was identified in each mold and the length along the long axis of the shoe and the width along the short axis of the shoe were measured. For baseline values and when no worn region had yet formed, the length and width of one tread block was recorded. The product of these two measurements comprised the size of the worn region on each shoe.