Fig. 19.

Expected treatment response after transarterial chemoembolization (TACE). Axial contrast-enhanced CT images of the liver obtained in late arterial phase are illustrated: Note: the wedge-shaped hyperdensity on illustrations b and c reflects the non-target parenchymal ethiodized oil deposition, not enhancement. a Pretreatment: typically used for bridging, debulking, or palliative treatment in patients with intermediate-stage hepatocellular carcinoma without vascular invasion. May be used alone or in combination with other treatments. b 1–3 months posttreatment: hyperdensity on unenhanced CT reflects ethiodized oil agent deposition in the tumor and at its periphery and reflects distribution of the embolic material. Ethiodized oil limits assessment of viability on CT. MRI helps assessment as oil agent does not mask enhancement. The following features may be seen: thin uniform rim enhancement around the treated zone, regional parenchymal enhancement, and intratumoral gas foci (up to 4–6 weeks posttreatment). c ≥ 6 months posttreatment: density and extent of ethiodized oil retention decreases with time. Size of necrotic zone decreases over time. Regional parenchymal enhancement resolves. Rim enhancement around the treated zone may persist for months to years. At any point posttreatment, presence of nodular arterial phase hyperenhancement, washout appearance, or enhancement similar to pretreatment indicates recurrence or residual viable tumor