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Background
Transjugular intrahepatic portosystemic shunt (TIPS) creation is a therapeutic procedure with the challenging step being the entry into the portal vein. Intracardiac echocardiography (ICE) is the contemporary technique to guide the real-time passage of a needle into the portal vein. Through this exhibit, we aim to describe the technique, advantages, and limitations of ICE during the TIPS procedure. The target audiences are clinical radiologists and radiology residents.

Educational Goals / Teaching Points
Review the significance of intracardiac echocardiography as a guidance technique for TIPS procedure, imaging description of the step-by-step ICE-guided TIPS, and advantages of ICE over conventional approaches to access the portal vein.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Hepatic venography is the commonly used technique that guides the needle to achieve portal vein access. However, the main limitation of this technique is that the needle passage cannot be directly visualized in real-time, which may lead to multiple needle passes, trans-capsular puncture, hemobilia (2%), hepatic artery puncture (1%) and hemorrhage (0.5%). The ICE catheter provides real-time feedback on the needle passage, thereby reducing the complication rate. It contains low-frequency (5 - 10 MHz) side-firing array transducers that enable enhanced tissue penetration and high-resolution imaging of vessels and bile ducts. ICE catheters are often referred to as IVUS in literature. The exquisite resolution helps to avoid the liver mass or tumor in proximity to the needle trajectory. For instance, in patients with portal vein thrombosis, the intravascular ultrasound (IVUS) confirms the needle entrance into the thrombosed portal vein and visualizes the wire position. IVUS aids in identifying the dominant cavernous collaterals in patients with chronic portal vein thrombosis complicated by cavernous transformation. It also provides direct transcaval access for individuals with Budd-Chiari syndrome. ICE-guided TIPS has reduced the procedure time (p = 0.02), Air Kerma (p = 0.01), fluoroscopy time (p = 0.003), and contrast volume (p = 0.003) compared to fluoroscopic-guided and marker wire-guided TIPS.

Conclusion
While traditionally employed in cardiology interventions, the efficacy of ICE catheter for TIPS has been well studied. The ultrasound probe enables the real-time entire needle trajectory. One can confidently place the stent in the accurate location, as the portal and hepatic vein anatomies are well visualized on IVUS.