Patients were admitted for 2 days and PVE was performed under light general anesthesia. The PVE procedures in the study patients were done by two experienced hepatobiliary interventional radiologists. The Onyx® liquid embolization system included a 1.5-mL vial of Onyx®, a 1.5-mL vial of DMSO, and three 1-mL delivery syringes. Before use, the vial contents were homogenized on a mixer for at least 15 minutes by gentle rotation according to the manufacturer’s instructions. The vial was used immediately after mixing to ensure even distribution of the tantalum and, therefore, reliable fluoroscopy visualization. Depending on the required depth of EVOH penetration into the embolization site, either Onyx®-18 (6% EVOH) or Onyx®-34 (8% EVOH) was used.

A 21-Gauge Chiba needle was introduced into a peripheral branch of the contralateral portal system under ultrasound guidance. According to the Seldinger technique, a 6-French introducer sheath was inserted into the main portal vein, which was then opacified to show the venous anatomy and look for a fistula, whose presence would contraindicate the procedure. A standard coaxial system composed of a guidewire and a DMSO-compatible 2.7-French microcatheter (Progreat®, Terumo, Japan) was used to selectively catheterize target second-order portal vein branches. The microcatheter was flushed with saline and DMSO was injected to fill the microcatheter dead space, thus preventing EVOH solidification in the catheter lumen. As soon as the microcatheter reached the most distal portal branches, EVOH was injected under fluoroscopic guidance, at a rate below 0.3 mL/min (Figure 2).

Preoperative right PVE in the same 74-year-old man with right-sided hepatocellular carcinoma. (A) Initial portography from the main portal vein through the left side showing normal anatomy; (B) fluoroscopic image during selective embolization of portal vein branches through a microcatheter showing filling of portal branches with EVOH; (C) fluoroscopic control demonstrating the distribution of highly radiopaque EVOH copolymer into the right portal vein branches; (D) final post-PVE portography from the main portal vein showing complete and successful occlusion of all right portal vein branches. PVE, portal vein embolization; EVOH, ethylene-vinyl alcohol.

The EVOH first traveled in the anterograde direction, along the normal venous flow, then occluded the vein downstream of the microcatheter, inducing reflux along the microcatheter, which ensured embolization of narrow portal vessels without requiring selective catheterization. Catheter removal was achieved easily as long as the EVOH reflux along the tip did not exceed 1 cm. After occlusion of all the small branches, the microcatheter tip was moved to a more proximal position, and a further EVOH injection was performed. This procedure was repeated in each target portal segmental branch. EVOH was administered until all target portal vessels were occluded. The proximal trunk (left or right) was occluded last, leaving a 1-cm non-occluded segment to facilitate surgical ligation during hepatectomy. Portal venography was then performed to check completeness of embolization. Finally, during removal of the sheath, the puncture track was embolized with sterile absorbable gelatin sponge to ensure hemostasis (Curaspon® Cura Medical, Assendelft, The Netherlands).

After the procedure, patients underwent thorough physical examinations for evidence of adverse events, as well as liver function tests and blood cell counts (4,29). Further investigations were performed as dictated by the clinical situation.

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