## 4 Discussion  
There is a major need for ancillary systems that are able to enhance the ability of operators to locate and enter the portal vein with relative ease. Many researchers have attempted to solve this problem by introducing various methods, such as guidance by per-operative ultrasound (US), magnetic resonance (MR) or intraprocedural carbon dioxide (CO\({}_{2}\)) angiography, but no method has consistently been able to successfully produce single puncture PV access in large cohorts [11; 13; 20; 21; 22]. Furthermore, these methods can increase procedure length and the risk of other complications, with little benefit to streamlining the PV puncture step [23]. In this study, we demonstrated the feasibility of pre-procedural 3D fusion imaging for guiding TIPS and DIPS procedures. Specifically, we showed that the 3 DFIG approach works by combining pre-procedural cross-sectional imaging (CBCT, CT or MR) with intraprocedural CBCT or angiogram imaging for real-time 3D-guided TIPS placement. The utility of this approach has been demonstrated using pre-procedural CT imaging in patients, in which the efficiency of placing the TIPS was clearly demonstrated [24; 25; 26]. The potential for the use of pre-procedural cross-sectional imaging for 3 DFIG TIPS procedures is vast, as most non-emergency patients have imaging available prior to their planned TIPS procedure. Due to underlying chronic liver disease, these patients are mostly followed by their hepatologists or gastroenterologists and also undergo routine surveillance imaging. Minimizing procedural times while maintaining accuracy is critical, especially in urgent and emergency TIPS procedures that are used to treat acute variecal bleeding. Although there was a limited number of subjects, we showed that 3 DFIG TIPS procedures using CBCT/angiography-fused images alone produced similar outcomes but with significantly shorter procedural times, which has important clinical implications for patients who do not have pre-procedural CT or MR imaging available to them [27]. Finally, we demon \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **3 DFIG TIPS with** & **3 DFIG TIPS with** & **3 DFIG TIPS with** & **3 DFIG DIPS with** \\  & **CBCT/Angio Alone** & **CT/CBCT/Angio** & **MR/CBCT/Angio** & **CT/CBCT/Angio** \\ \hline Technical Success & 7/7 & 10/10 & 10/10 & 8/8 \\ Complications & 0 & 0 & 0 & 0 \\ Single PV Puncture & 7/7 (100\%) & 9/10 (90\%) & 9/10 (90\%) & 7/8 (88\%) \\ TPT (min) & 14.4 \(\pm\) 1.0 * & 22.4 \(\pm\) 5.1 & 18.7 \(\pm\) 3.1 & 14.1 \(\pm\) 1.1 \\ TTC3D (min) & 3.0 \(\pm\) 0.8 * & 8.5 \(\pm\) 3.4 & 7.5 \(\pm\) 2.7 & 3.9 \(\pm\) 0.7 \\ MFT (min) & 3.0 (IQR, 3.0-3.0) * & 4.0 (IQR, 3.0-5.3) & 4.0 (IQR, 3.0-5.3) & 3.0 (IQR, 3.0-3.0) \\ \hline \hline \end{tabular}
\begin{tabular}{c} TPT, total procedure time (mean \(\pm\) SD); TTC3D, total time to create 3D fusion images (mean \(\pm\) SD); MFT, median fluoroscopy time (median with IQR). * denoted as \(p\) < 0.05 compared to CT/CBCT/Angiography or MR/CBCT/Angiography group \\ \end{tabular}
\end{table} 
Table 1: Technical outcomes of the 3 DFIG TIPS procedures. strated the feasibility of using the 3 DFIG DIPS procedure, which could prove to be especially relevant in patients for whom the traditional TIPS procedure is contraindicated [28]. The addition of 3 DFIG to the TIPS and DIPS procedures led to a 100% success rate, with no complications and short fluoroscopy and procedure times. Most importantly, the number of needle puncture attempts that was required to gain PV access was low compared to the \"blind\" portosystemic needle punctures that are only guided by fluoroscopy [16; 29]. Transvenous intrahepatic access to the PV is the most crucial and also most dangerous step of the TIPS procedure.