Impact of intrahepatic veno-venous shunts on wedged hepatic and direct portal pressures

Abstract

Segmentation was performed in 3DSlicer (v4.5). For HV and PV segmentation, fiducial seeds were placed and a semiautomated simple region growing algorithm was applied, followed by marching cubes to generate a mesh. For liver segmentation, slices were contoured, followed by a robust statistics segmenter and mesh generation by marching cubes. The final model for 3D printing was generated by performing a boolean subtraction of vasculature, and exported as a stereolithography (.STL) file. The model was then printed on a ProJet 3500 HD Max in VisiJet Crystal, a translucent acrylate polymer. To better visualize HVs and PVs, the interior walls were painted in vibrant colors. Results: The resultant liver model features parenchyma formed with translucent acrylate polymer, enabling visualization of the separately colored HVs and PVs. The HVs and PVs are hollow, allowing evaluation of the geometric relationships between venous systems and "dry run" catheter interrogation. Selection of a post-printing method for coloring the HVs and PVs was important as it greatly reduces the complexity and expense of the 3D print itself, when compared to a multi-color, multi-material approach. Conclusions: As 3D printers become ubiquitous tools of modern medical care, routine 3D printing for TIPS planning is feasible. Using on-site segmentation, a physically transparent liver model may be produced containing hollowed, color coded HVs and PVs to facilitate TIPS planning and potentially decrease morbidity.