The Novel X-Ray Visible Zein-Based Non-adhesive Precipitating Liquid Embolic HEI_{E1_2017}: An Exploratory Study

Purpose: To investigate the novel zein-based non-adhesive precipitating liquid embolic HEI_{E1_2017}.

Materials and methods: Zein-based liquid embolics are an own class of embolization material. In this study, HEI_{E1_2017}, a novel zein-based liquid embolic, was investigated. Visibility was assessed in vitro in CT and MRI phantoms, embolization characteristics were assessed in vivo in the kidneys of 12 pigs. Components of HEI_{E1_2017} were zein as occlusion material, ethanol as solvent, and iodized oil as radiopaque material. HEI_{E1_2017} was used in pure (HEI-PURE) and manually modified (HEI-MOD) form and compared with 6% ethylene vinyl alcohol copolymer (EVOH). Different radiological methods (CT, MRI, DSA, cone-beam CT, and micro-CT) and histopathologic analyses were applied to compare visibility and vascular occlusion patterns.

Results: In CT phantoms, all embolics were definitely visible as hyperdense materials. In MRI phantoms, signal-to-noise ratio was highest for HEI-PURE, followed by HEI-MOD and EVOH. In all kidneys, embolization procedures were technically successful and without complications. In DSA, all embolics were definitely visible during and after embolization. Only EVOH caused substantial artifacts in cone-beam CT and CT. In micro-CT and histopathology, HEI-PURE showed a homogeneous occlusion from segmental arteries to glomerular capillaries. HEI-MOD demonstrated the deepest vascular penetration (up to the level of peritubular capillaries), but with an inhomogeneous distribution. For EVOH, there was inhomogeneous vascular occlusion from segmental arteries to glomerular capillaries.

Conclusion: HEI_{E1_2017} is a promising novel zein-based liquid embolic. Further preclinical and clinical studies with higher case numbers and long-term follow-up are needed to further assess the value of this embolic material.