Techniques of ultraselective conventional transarterial chemoembolization for hepatocellular carcinoma

Ultraselective conventional transarterial chemoembolization (cTACE), a specialized form of cTACE, involves injecting iodized oil emulsions combined with chemotherapeutics and gelatin sponge (GS) slurry into the most distal portion of the tumor-feeding sub-subsegmental hepatic artery and has demonstrated curative potential for treating hepatocellular carcinoma (HCC). Advancing a microcatheter to the point of minimal backflow of embolic agents, called a semi-wedged condition, facilitates the non-physiological injection of embolic agents into HCC, even with hypovascular tumor portions. Ultraselective cTACE is primarily indicated for HCC ≤5 cm using a thin microcatheter-microwire system under computed tomography (CT)/cone-beam CT (CBCT), as well as TACE guidance software if available. Optimal embolic agents, such as water-in-oil emulsions and GS slurry of approximately 0.2–0.5 mm in diameter, should be prepared to perform effective ultraselective cTACE. In cases of multiple tumor-feeding arteries, embolization should begin at the distal or minor feeder and end at the proximal or main feeder. The endpoint of ultraselective cTACE is the disappearance of tumor staining and complete occlusion of tumor feeders visible via digital subtraction angiography. More accurate endpoints are emulsion accumulation within the tumor and at an appropriate safety margin (5 mm for <25 mm and 10 mm for ≥25 mm tumors) observed via CT/CBCT. The technical success of ultraselective cTACE is evaluated using unenhanced CT acquired within 1 week post-procedure. Magnetic resonance imaging is preferable to assess tumor response because CT can easily miss peritumoral recurrence due to artifacts caused by dense accumulation of iodized oil in the tumor. • Ultraselective cTACE is done at the tumor-feeding sub-subsegmental hepatic artery. • Iodized oil emulsion mixed with chemotherapeutic and gelatin sponge slurry are used. • The endpoint is absence of tumor staining and complete occlusion of tumor feeders. • Technical success is evaluated by unenhanced CT within 1 week post-procedure.