Loco-regional treatment of hepatocellular carcinoma: Role of contrast-enhanced ultrasonography

Abstract

Hepatocellular carcinoma (HCC) is one of the few cancers for which locoregional treatments (LRTs) are included in international guidelines and are considered as a valid alternative to conventional surgery. According to Barcelona Clinic Liver Cancer classification, percutaneous treatments such as percutaneous ethanol injection, radiofrequency ablation and microwave ablation are the therapy of choice among curative treatments in patients categorized as very early and early stage, while transcatheter arterial chemoembolization is considered the better option for intermediate stage HCC. A precise assessment of treatment efficacy and surveillance is essential to optimize survival rate, whereas residual tumor requires additional treatment. Imaging modalities play a key role in this task. Currently, contrast-enhanced computed tomography/magnetic resonance imaging are considered the standard imaging modalities for this purpose. Contrast enhanced ultrasound (CEUS), using second generation contrast agents, plays an increasingly important role in detecting residual disease after LRTs. CEUS is a straightforward to perform, repeatable and cost-effective imaging modality for patients with renal failure or iodine allergies. Due to the ability to focus on single regions, CEUS can also provide high temporal resolution. Moreover, several studies have reported the same or better diagnostic accuracy as contrast-enhanced computed tomography for assessing tumor vascularity 1 mo after LRTs, and recently three-dimensional (3D)-CEUS has been reported as a promising technique to improve the evaluation of tumor response to therapy. Furthermore, CEUS could be used early after procedures in monitoring HCC treatments, but nowadays this indication is still debated, and data from literature are conflicting, especially after transcatheter arterial chemoembolization procedure.

Keywords: Contrast-enhanced ultrasonography; Hepatocellular carcinoma; Liver; Radiofrequency ablation; Transcatheter arterial chemoembolization; Ultrasound.

Figure 1

Typical contrast-enhancement pattern of a hepatocellular carcinoma in a 72-year-old woman with hepatitis C virus related cirrhosis. A: In the arterial phase (24 s after the injection of a microbubble-based contrast agent) contrast enhanced ultrasound depicts a hypervascular tumor sized 2 cm in the IV liver segment (white arrow); B: In the late phase, 199 s after the injection, the lesion shows a mild wash-out (white arrow).

Figure 2

Intrazonal recurrence after radiofrequency ablation in a 79-year-old woman with hepatitis C virus-related cirrhosis. A: Gray-scale ultrasound image achieved 1 yr after ablation shows a heterogeneous hyperechoic nodule (circle); B: Contrast enhanced ultrasound (CEUS) imaging achieved 15 s after injection shows a nodular token of arterial phase hyperenhancement (white arrow); C: CEUS image obtained at 2 min shows a wash-out. The patient underwent a new radiofrequency ablation in the same session. Simultaneously CEUS shows small hemangioma in the same segment (white arrow).

Figure 3

Extrazonal recurrence. Follow-up of hepatocellular carcinoma treated with microwave ablation in a 79-year-old man with hepatitis C virus and ethanol alcohol-related cirrhosis. A: Contrast enhanced ultrasound image achieved 12 mo after treatment shows a peripheral arterial enhancement 20 s after injection (white arrow); B: Subsequent wash-out is evident at 3 min after injection.

Figure 4

Post procedural contrast enhanced ultrasound (20 min after microwave ablation) in a 72-year-old man with chronic hepatitis C virus-related hepatocellular carcinoma. Reactive hyperemia achieved immediately after the procedure (22 s). A: Thick and regular rim of arterial phase hyperenhancement surrounds the treatment area (arrows); B: Absence of wash-out in the late phase (4 min) confirms the reactive significance of hyperemia.