Feasibility of percutaneous transabdominal portosystemic shunt creation

Implementation of an electromagnetic tracking system for accurate intrahepatic puncture needle guidance: accuracy results in an in vitro model

RATIONALE AND OBJECTIVES

Electromagnetic tracking potentially may be used to guide percutaneous needle-based interventional procedures. The accuracy of electromagnetic guided-needle puncture procedures has not been specifically characterized. This article reports the functional accuracy of a needle guidance system featuring real-time tracking of respiratory-related target motion.

MATERIALS AND METHODS

A needle puncture algorithm based on a "free-hand" needle puncture technique for percutaneous intrahepatic portocaval systemic shunt was employed. Preoperatively obtained computed tomographic images were displayed on a graphical user interface and registered with the electromagnetically tracked needle position. The system and procedure was tested on an abdominal torso phantom containing a liver model mounted on a motor-driven platform to simulate respiratory excursion. The liver model featured two hollow tubes to simulate intrahepatic vessels. Registration and respiratory motion tracking was performed using four skin fiducials and a needle fiducial within the liver. Success rates for 15 attempts at simultaneous puncture of the two "vessels" of different luminal diameters guided by the electromagnetic tracking system were recorded.

RESULTS

Successful "vessel" puncture occurred in 0%, 33%, and 53% of attempts for 3-, 5-, and 7-mm diameter "vessels," respectively. Using a two-dimensional accuracy prediction analysis, predicted accuracy exceeded actual puncture accuracy by 25%-35% for all vessel diameters. Accuracy outcome improved when depth-only errors were omitted from the analysis.

CONCLUSIONS

Actual puncture success rate approximates predicted rates for target vessels 5 mm in diameter or greater when depth errors are excluded. Greater accuracy for smaller diameter vessels would be desirable for implementation in a broader range of clinical applications.

Electromagnetic Tracking–Guided Percutaneous Intrahepatic Portosystemic Shunt Creation in a Swine Model

Electromagnetic tracking potentially may be used to guide percutaneous needle-based interventional procedures. This brief report describes our initial experience with an electromagnetic guidance system featuring real-time tracking of respiratory-related target motion using an internal fiducial. An algorithm based on a "freehand" needle puncture technique was employed to puncture the right portal vein and a right hepatic vein for percutaneous intrahepatic portosystemic shunt in a swine model. Preoperative computed tomographic images registered with the electromagnetically tracked needle position were displayed for guidance. Successful puncture was confirmed angiographically. Simultaneous percutaneous transhepatic puncture of the targeted veins was accomplished on the initial attempt.

Transjugular Intrahepatic Portosystemic Shunt Creation in Budd-Chiari Syndrome: Percutaneous Ultrasound-Guided Direct Simultaneous Puncture of the Portal Vein and Vena Cava

Budd-Chiari syndrome (BCS) is an uncommon disorder that can be life-threatening, depending on the degree of hepatic venous outflow obstruction. Transjugular intrahepatic portosystemic shunt (TIPS) provides decompression of the congested liver but the hepatic vein obstruction makes the procedure more difficult. We describe a modified method that involved a single percutaneous puncture of the portal vein and inferior vena cava simultaneously for TIPS creation in a patient with BCS.