Prospective Evaluation of Passive Expansion of Partially Dilated Transjugular Intrahepatic Portosystemic Shunt Stent Grafts - A Three-Dimensional Sonography Study

Purpose: To prospectively investigate early expansion kinetics of underdilated self-expanding stent grafts used for transjugular intrahepatic portosystemic shunt (TIPS) creation. Materials and Methods: Twenty patients (7 female; mean age 66 y; range, 31-80 y) with liver cirrhosis undergoing TIPS creation for variceal bleeding (n = 5), refractory ascites (n = 14), or both (n = I) with underdilation of 10-mm stent grafts received two-dimensional (2-D) and three-dimensional (3-D) ultrasound (US) examinations immediately after TIPS creation and I and 6 weeks later. Orthogonal views of the TIPS within the parenchymal tract were reconstructed from 3-D volume data sets acquired in longitudinal orientation of the stent. 2-D images and reconstructed 3-D images were used for blinded diameter measurements. Measurement technique was validated with intrainterventional plain radiographs with a sizing catheter as the gold standard. Diameter changes over time and interrelations with patient characteristics (null hypothesis: no expansion, no interrelation) were analyzed using a general linear model for repeated measures. Results: After dilation to 8-mm diameter, 2-D and 3-D measurements showed stent recoil (mean diameter 7.7 mm 0.21 and 7.6 mm 0.17, respectively). Diameter increased significantly from initial measurements to measurements at I and 6 weeks (2-D, 8.8 mm 0.24 and 9,4 mm 0.15, both P < .001; 3-D, 8.7 mm 0.27 and 9.4 mm 0.11, both P < .001). Validation measurements showed no significant differences between 2-D or 3-D US and gold standard. There were no statistically significant associations between stent expansion and clinical parameters (sex, P = .78; age, P = .82; etiology/grade of cirrhosis, P = .99; indication for TIPS, P = .78, liver stiffness, P = .70). Conclusions: Underdilated self-expanding stent grafts used for TIPS creation significantly expand within first 6 weeks after intervention. These changes can be noninvasively monitored using 3-D US.