Introduction Integrated imaging suites possess great clinical significance. In the case of dual MRI and X-ray suites, devices designed to be used in their workflow have lagged in development due to engineering challenges presented by the unique working environment. In the field of neuro-intervention, device visibility is paramount. Such device efficacy must be tested in vitro in vascular phantoms that mimic the in vivo environment; however, the imaging physics of X-ray and MRI mean that a standard phantom in one imaging environment cannot be used effectively in the other. Here, we sought to develop a carotid artery and vertebral bone phantom using poly(vinyl) alcohol cryogel (PVA-C) and epoxy resin to navigate neuro-interventional catheters in integrated MR and X-ray imaging suites.
Methods Human-scale models of a carotid artery and cervical spine were adapted from the NIH 3D Print Exchange and printed using an Ultimaker 3 (Ultimaker, Geldermalsen, Netherlands). The vertebral model was used to create a negative silicone mold.
Bone Equivalent MaterialEpoxy resin representing a homogeneous mix of cortical and trabecular spongiosa was made using established methods. 36.4% Araldite GY 6010 and Jeffamine T-403 (Huntsman, The Woodlands, TX) were mixed (w/w) with 25.5% silicon dioxide (40–100 mesh sand) and 23.5% calcium carbonate (Sigma Aldrich, St. Louis, MO). The mixture was degassed, poured into the vertebral silicone mold, and cured at 20°C for 72 hours.
PVA-C Phantom PVA solution was made using previously established methods. Sevol Grade 165 PVA powder was used to create 1.5 L 10% (w/w) PVA. The solution was poured into a 1.8 L container, and the carotid artery and epoxy vertebral models were submerged. Four complete freeze-thaw cycles were performed. The carotid artery model was removed, leaving open lumens in the cryogel.
ImagingA gradient echo sequence was acquired at 3T (Discovery MR 750w, GE Healthcare, Milwaukee, WI). A 30 cm × 30 cm flat panel C-arm X-ray system guidance (Cios Alpha, Siemens Healthineers, Munich, Germany) was used to acquire X-ray images of the phantom.
Results MR and X-ray images showed a phantom with bone- and tissue-like properties (figure 1). Rigidity of the PVA-C was found to be sufficient for future navigation studies with test devices.
Conclusions The phantom showed promise as an important tool in imaging research to assess and improve future neuro-interventional devices. These initial steps provide the foundation for a human-scale phantom to test devices for integrated MR and X-ray imaging techniques.
Disclosures B. Kilbride: None. C. Jordan: None. P. Kumar: None. T. Moore: None. M. Wilson: None. S. Hetts: None.
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