Percutaneous ablation for small hepatocellular carcinoma

Hepatocellular carcinoma is increasingly detected at small size, usually 5 cm or smaller in diameter. For small hepatocellular carcinoma, percutaneous ablation is a potentially curative treatment. Ethanol injection is able to achieve a complete response of 70–80% and a 5-year survival of 40–60% in the treatment of hepatocellular carcinoma of 3 cm or less. Radiofrequency ablation has emerged as the more powerful alternative method. Randomized controlled trials show that radiofrequency ablation offers a higher complete response at fewer treatment sessions and better survival compared with ethanol injection. Microwave ablation has been demonstrated to be equivalent to radiofrequency ablation in both local efficacy and long-term outcome. Laser ablation is mainly applied in clinical settings in Europe. Nowadays, percutaneous ablation is commonly accepted as the best option for patients with small hepatocellular carcinoma who are not candidates for surgical resection or liver transplantation. However, whether it can compete with surgery as the first-line treatment has long been debated. There are some retrospective studies and only a few randomized controlled trials to compare the two modalities. The currently available data are not robust enough to draw a solid conclusion. This review article provides an overview of the current status of percutaneous ablation in management of small hepatocellular carcinoma and also focuses on comparison with surgical resection.     

Prognostic factors in patients with small hepatocellular carcinoma treated by percutaneous ethanol injection

BACKGROUND: Percutaneous ethanol injection (PEI) has been widely performed and is now accepted as a viable alternative to hepatic resection in patients with small hepatocellular carcinomas (HCC). However, only a few extensive investigations have been conducted regarding the prognostic factors for HCC patients treated with PEI. METHODS: We investigated the prognostic factors in 100 patients with small HCC who had undergone PEI. Univariate analysis and multivariate analysis with Cox's proportional hazards model were used to determine the factors potentially related to survival. For clinical application, a prognostic index was calculated based on the regression coefficients of the independent variables identified from the multivariate analysis. RESULTS: Median survival time and 1, 3 and 5 year survival rates were 71 months and 100, 84 and 62%, respectively. Among the 15 potential prognostic variables investigated, only three variables, namely a serum albumin level < or = 3.5 g/dL, the presence of tumor stain and a serum glutamic oxaloacetic transaminase level > 66 IU/L, were identified as factors independently associated with a shorter survival. A prognostic index based on the regression coefficients of these three factors was proposed to classify patients into three groups, those with a good (5 year survival rate 91%), intermediate (64%) and poor prognosis (22%). CONCLUSIONS: The results of the present study may be useful in predicting the survival of HCC patients treated with PEI and in the design and analysis of future clinical trials of PEI for HCC.     

Local injection therapy for hepatocellular carcinoma

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world and ranks the third most common cause of cancer-related death. Surgical resection, liver transplantation and percutaneous ablation are generally considered the only curative treatment for early stage HCC. Besides the limitations of insufficient organ donors and a long waiting time for liver transplantation, however, resection is applied only to patients with good hepatic reserve and localized tumors, with a resectability of 30%. DATA SOURCES: Local ablation therapy, which is minimally invasive but contributes to the significant improvement of survival in patients with unresectable tumor, hasbeen widely used in treating small HCC. Among the techniques of local therapy, percutaneous ethanol injection (PEI) with a complete response in 80% of HCCs less than 3 cm has been accepted as an alternative to surgery in patients with small HCC. Moreover, percutaneous hepatic quantified ethanol injection (PHQEI) or PEI according to the standard criteria has been confirmed to benefit patients with HCC, especially when quantified ethanol is given at a short interval (QESI, the interval was 2-3 days). RESULT: Several limitations related to local percutaneous methods may result in incomplete therapeutic effect in case of larger HCC nodules (>3 cm). CONCLUSION: The combined use of different methods according to the clinical status of patients or tumors may be essential to the effective treatment of HCC.     

Postoperative recurrence in hepatocellular carcinoma: Comparison between percutaneous ethanol injection and radiofrequency ablation.

AIM: Recently percutaneous ethanol injection (PEI) turned into percutaneous radiofrequency ablation (PRFA), and it has become widely used for the treatment of hepatocellular carcinoma (HCC). The present study was to compare the incidence in postoperative HCC recurrence between these two therapeutic approaches. METHODS: One hundred and sixty-eight first-time HCC in patient cases were chosen for PEI (n=94) and PRFA (n=74). The localized recurrence rate based on the operator's experience in percutaneous treatment for HCC (on <5 years versus >/=5 years experience) was examined. RESULTS: The PRFA group demonstrated a significantly lower localized recurrence rate within 2 years than the PEI group (8% and 22%, respectively, P<0.01). The local recurrence rate of HCC within 2 years after PEI was significantly lower in those for whom the operator's experience was more than 5 years compared to those for whom it was less than 5 years (12% versus 24%, respectively, P<0.05). In contrast, after PRFA there was no significant difference between these two groups of <5 years and of >/=5 years experience (8% versus 8%, respectively, P=0.98). CONCLUSION: The present study demonstrated that PRFA resulted in a lower rate of local recurrence in comparison to conventional PEI, regardless of the operator's experience.     

Radiofrequency ablation versus ethanol injection for early hepatocellular carcinoma: A randomized controlled trial

Objective. To compare percutaneous ethanol injection (PEI), the standard approach which has been used for many years to treat early non-surgical hepatocellular carcinoma (HCC) in cirrhotic patients, and radiofrequency ablation (RFA), which has become an interesting alternative. Material and methods. A randomized trial was carried out on 139 cirrhotic patients in Child-Pugh classes A/B with 1–3 nodes of HCC (diameter 15–30 mm), for a total of 177 lesions. Patients were randomized to receive RFA (n=70) or PEI (n=69). The primary end-point was complete response (CR) 1 year after the percutaneous ablation of all HCC nodes identified at baseline. Secondary end-points were: early (30–50 days) CR, complications, survival and costs. Results. In an intention-to-treat analysis, 1-year CR was achieved in 46/70 (65.7%) and in 25/69 (36.2%) patients treated by RFA and PEI, respectively (p=0.0005). For lesions >20 mm in diameter, there was a larger CR rate in the RFA group (68.1% versus 26.3%). An early CR was obtained in 67/70 (95.7%) patients treated by RFA compared with 42/64 (65.6%) patients treated by PEI (p=0.0001). Complications occurred in 10 and 12 patients treated by RFA and PEI, respectively. The overall survival rate was not significantly different in the RFA versus PEI arm (adjusted hazard ratio=0.88, 95% CI: 0.50–1.53). There was an incremental health-care cost of 8286 € for each additional patient successfully treated by RFA. Conclusions. The 1-year CR rate after percutaneous treatment of early HCC was significantly better with RFA than with PEI but did not provide a clear survival advantage in cirrhotic patients.     

经皮冷消融联合酒精注射治疗不能切除的肝细胞癌

目的：评价经皮冷消融联合经皮酒精注射(PEI)治疗不能切除的肝细胞癌(HCC)的有效性和安全性。方法：65例HCC患者共105个肿瘤块接受经皮冷消融治疗。冷消融采用cRYOCARE系统，氩气作为冷却剂，共给予2次冷却-复温循环，每次冷却时冷冻刀顶端温度为-180℃。其中36例瘤块直径大于6cm的患者，在冷消融治疗后1～2周接受PEI治疗，每周1次，连续4～6次。结果：在平均随访期为16个月(5～21个月)内，32例(49．2％)无瘤生存，22例(33．8％)生存但有肿瘤复发，其中2例骨转移，3例肺转移，其余17例为肝内复发，但仅有3例是原先冷消融部位复发。在随访1年以上的41例患者中，有32例(78％)迄今仍生存，包括无复发和有复发的病例。8例(12．3％)死于肿瘤复发，3例(4．6％)死于非癌性原因。有CT复查资料的43例中，38例(88．4％)显示肿瘤缩小。冷消融治疗后22例行瘤块活检，除1例外，均显示为坏死性疤痕组织。冷消融治疗前血清甲胎蛋白(AFP)升高的病例中，91．3％在治疗后3～6个月内AFP下降至正常或接近正常。冷消融并发症包括1例发生肝包膜开裂，4例发生一过性血小板降低，2例发生无症状性右侧胸腔积液，2例在原先冷消融部位发生肝脓肿。结论：经皮冷消融为不能手术切除的HCC提供了安全而有效的治疗手段。     

Prospective cohort study of transarterial chemoembolization for unresectable hepatocellular carcinoma in 8510 patients

BACKGROUND & AIMS: To elucidate the survival of the patients with unresectable hepatocellular carcinoma (HCC) who underwent transcatheter arterial lipiodol chemoembolization (TACE) and to analyze the factors affecting the survivals. METHODS: During the last 8 years, a nationwide prospective cohort study was performed in 8510 patients with unresectable HCC who underwent TACE using emulsion of lipiodol and anticancer agents followed by gelatin sponge particles as an initial treatment. Exclusion criteria were extrahepatic metastases and/or any previous treatment prior to the present TACE. The primary end point was survival. The survival rates were calculated by the Kaplan-Meier method. The multivariate analyses for the factors affecting survival were evaluated by the Cox proportional hazard model. The mean follow-up period was 1.77 years. RESULTS: For overall survival rates by TACE, median and 1-, 3-, 5-, and 7-year survivals were 34 months, 82%, 47%, 26%, and 16%, respectively. Both the degree of liver damage and the tumor-node-metastasis (TNM) system proposed by the Liver Cancer Study Group of Japan demonstrated good stratification of survivals (P = .0001). The multivariate analyses showed significant difference in degree of liver damage (P = .0001), alpha-fetoprotein value (P = .0001), maximum tumor size (P = .0001), number of lesions (P = .0001), and portal vein invasion (P = .0001). The last 3 factors could be replaced by TNM stage. The TACE-related mortality rate after the initial therapy was .5%. CONCLUSIONS: TACE showed safe therapeutic modality with a 5-year survival of 26% for unresectable HCC patients. The degrees of liver damage, TNM stage, and alpha-fetoprotein values were independent risk factors for patient survival.     

Percutaneous ethanol injection, radiofrequency and their combination in treatment of hepatocellular carcinoma

AIM: To evaluate the therapeutic effect and the indication of percutaneous ethanol injection (PEI), radiofrequency ablation (RFA) and their combination in treatment of hepatocellular carcinoma (HCC). METHODS: Two hundred and fifty-five patients with HCC received treatment of PEI, RFA or their combination. Groupl (< 3 cm in diameter, n=85) was treated with PEI, group2(< 3 cm in diameter, n=153) with RFA. Group3 (>3 cm in diameter, n=86) was divided into two groups. Group 3a (n=34) was treated with RFA, while group 3b (n=52) was treated with RFA for 2 wk after transcatheter arterial chemoembolization or PEI. Contrast-enhanced sonography was performed for 61 patients before and after RFA. Liver function and serum alpha-fetoprotein (AFP) were measured for all patients. Changes of the lesions on ultrasound and contrast-enhanced CT/MRI were evaluated for assessing the therapeutic responses. The 1-, 2-, 3- and 5-year survival rates were recorded after treatment. RESULTS: In group 1, the complete necrosis rate of lesions after 1 mo was 77.6% (66/85). The level of AFP declined conspicuously after 1 mo. The 1-, 2-, 3- and 5-year survival rate after treatment was 80.0% (52/65), 60.4% (32/53), 52.5% (21/40) and 33.3% (7/21), respectively. In group 2, the complete necrosis rate of lesions after 1 moh was 92.2% (141/153). The level of AFP decreased conspicuously after 1 mo. The 1-, 2-, 3- and 5-year survival rate after treatment was 94.6% (88/93), 73.2% (52/71), 63.5% (33/52) and 46.4% (13/28), respectively. In group 3a, the complete necrosis rate of lesions after 1 mo was 23.5% (8/34). AFP dropped down to the normal level in only one patient after 1 mo. The 1-, 2- and 3-year survival rate after treatment was 47.6% (10/21), 42.9% (6/14) and 27.3% (3/11), respectively. Only one patient was still alive after 5 years. In group 3b, the complete necrosis rate of lesions after 1 mo was 57.7% (30/52). The level of AFP decreased after 1 mo. The 1-, 2-, 3- and 5-year survival rate after treatment was 68.6% (24/35), 46.2% (12/26), 36.8% (7/19) and 27.3% (3/11), respectively. CONCLUSION: The therapeutic effect of RFA on small HCC is better than that of PEL Small HCC is the optimal indication of RFA. For recurrent HCC (diameter>3 cm), the combined treatment of RFA and PEI/ACE should be used.     

The Islanding effect - a special method of percutaneous peritumor ethanol injection for hepatocellular carcinoma: 15-year follow-up outcome

Percutaneous ethanol injection is a well-known ablation therapy for hepatocellular carcinoma and is well-tolerated, inexpensive, and effective with few adverse events. In this study, another type of ethanol injection was introduced in the present study.Sixty two patients with hepatocellular carcinoma received 133 percutaneous peritumor ethanol injection treatments and the 15-year follow-up outcomes were analyzed through a collected database.The technical efficiency was 89.5% (119/133 treatments) after the first percutaneous peritumor ethanol injection procedure. However, after the second repeated percutaneous peritumor ethanol injection procedure, technical efficiency increased to 98.5% (131/133 treatments). The 1 year, 3 years, 5 years, 10 years, and 15 years rates of tumor recurrence were 12.9%, 50.0%, 59.7%, 74.2%, and 74.2%, respectively. Multivariate analysis demonstrated that diabetes, Child–Pugh class B, and tumor size greater than 2 cm were significantly related to tumor recurrence. The 1 year, 3 years, 5 years, 10 years, and 15 years rates of overall survival were 98.4%, 83.6%, 61.3%, 19.4%, and 0%, respectively. Multivariate analysis demonstrated that Child–Pugh class B, tumor size greater than 2 cm, and multiple tumors were significantly related to overall survival.Compared with other ablation methods (including peritumor ethanol injection), percutaneous peritumor ethanol injection can avoid tumor ruptures, reduce tumor proliferation and metastasis, and is suitable for the treatment of small tumors. In addition, when combined with other treatment methods, percutaneous peritumor ethanol injection can form a tumor metastatic isolation zone in advance and improve the comprehensive treatment effect.     

Evaluation of transcatheter arterial embolization prior to percutaneous tumor ablation in patients with hepatocellular carcinoma: a randomized controlled trial.

BACKGROUND: Transcatheter arterial embolization (TAE) may reduce the risk of hepatocellular carcinoma (HCC) recurrence when performed before percutaneous tumor ablation (PTA), either percutaneous ethanol injection therapy (PEIT) or radiofrequency ablation (RFA). We conducted a randomized, controlled trial comparing the use of TAE combined with percutaneous ethanol injection therapy (TAE/PEIT) to the use of PEIT only to assess the effects on HCC recurrence and survival. We continued the study after the introduction of RFA and compared TAE combined with RFA (TAE/RFA) with RFA only. METHODS: Between March 1997 and April 2001, 42 HCC patients were enrolled who satisfied the following inclusion criteria: (1) uninodular HCC as determined by angiography under computed tomography, (2) arterial hypervascularity, and (3) no prior history of HCC treatment. Twenty-two patients were treated with TAE/PTA (PEIT, 12; RFA, 10) and 20 patients with PTA only (PEIT, 14; RFA, 6). RESULTS: There were four cases of local recurrence in the PTA-only group and none in the TAE/PTA group (P=0.043). The four patients with local recurrence were treated with PEIT. None of the patients treated with RFA showed local recurrence. The effect of TAE on overall recurrence was not significant (P=0.4179). In the multivariate analysis, prior TAE was not significant for survival (P=0.514). CONCLUSIONS: TAE has a limited use in suppressing local recurrence when performed before PEIT but not before RFA.     

Choice of treatments for small hepatocellular carcinoma: Hepatectomy, embolization or ethanol injection

The results of hepatectomy, percutaneous ethanol injection therapy and transcatheter arterial embolization for small hepatocellular carcinoma (HCC) of 3 cm or less in diameter from the published literature were compared with the authors' experiences with surgical treatment. The survival rates for those treated by hepatectomy and ethanol injection were almost the same, being more than 90% at 1 year and 70% at 3 years. The overall results achieved by embolization were inferior to those achieved by the other two therapeutic modalities, although the 1 year survival rate was not worse. The cancer-free survival rates after hepatectomy and ethanol injection were also similar. Most of the patients with small HCC had associated liver cirrhosis or chronic active hepatitis, but the degree of liver dysfunction and the level of hepatic reserve varied. Anatomically, the number, size, and location of the cancer also varies. Choice of treatment for small HCC should be made based upon the degree of liver function and the anatomic status of the cancer. For example, a patient with multiple (more than four) cancer nodules is a good candidate for embolization. Ethanol injection is indicated for a small HCC, deeply seated in a severely diseased liver. Hepatectomy is the first choice for a small HCC situated near the surface of a liver with relatively good liver function.     

Multiple-needle insertion method in percutaneous ethanol injection therapy for liver neoplasms

One of the shortcomings of percutaneous ethanol injection therapy (PEIT) is that many sessions are necessary to accomplish the treatment. In order to reduce the number of treatment sessions, we inserted two or three needles before injection of ethanol was begun. Using the multiple-needle insertion method, we markedly reduced the number of treatment sessions. Histopathologic examination, imaging techniques, and serum alpha-fetoprotein levels showed efficacy of PEIT using the multiple-needle insertion method. No serious complication occurred. Levels of transient pain, fever, and the feeling of intoxication did not seem to be different from those occurring with the conventional method. Multiple-needle insertion method may be valuable as a method for reducing the number of treatment sessions necessary and thus shortening the treatment period.     

Evidence-based medicine in the treatment of hepatocellular carcinoma

The incidence of hepatocellular carcinoma is increasing worldwide. Diagnosis at early stage is crucial to allow the application of curative treatments, that are the sole hope to increase their life expectancy. Surgical resection and liver transplantation are considered the first line options for early tumors, although there is no agreement on which is the best treatment approach. Resection achieves excellent results in patients with single tumors, absence of portal hypertension and normal bilirubin, but is limited by the high recurrence rate. Liver transplantation also achieves excellent results in patients with single tumors smaller than 5 cm or even three nodules smaller than 3 cm. However, this procedure is hampered by the shortage of donors and the increasing waiting times that have reduced their intention-to-treat outcomes. Treatment while waiting for a donor is controversial, but radical antitumoral therapies seem cost-effective in long waiting times. Percutaneous therapies are reserved for patients with single non-surgical tumors. More than 60 randomized clinical trials have been published to assess treatments for patients with advanced tumors, but there is no definitive evidence of survival benefits. A recent randomized trial reported that chemoembolization may benefit HCC patients in terms of survival, but additional studies to confirm this data are recommended.     

Portal vein thrombosis complicating hepatocellular carcinoma. Value of ultrasound-guided fine-needle biopsy of the thrombus in the therapeutic management

Abstract: During a 4-year period portal vein thrombosis was diagnosed in 20 Child class A patients with cirrhosis by means of ultrasound and ultrasound-Doppler study. Seventeen of them showed single or multiple focal liver lesions diagnosed as hepatocellular carcinoma by ultrasound-guided fine-needle biopsy and the remaining three a coarse liver echo-pattern without focal lesions. One patient was found to have developed portal vein thrombosis after the fifth ethanol injection of a single hepatocellular carcinoma lesion 17 mm in diameter. Ultrasound-guided fine-needle biopsy of the thrombus was performed on all the patients: portal vein thrombosis was neoplastic in 13 cases and non-neoplastic in seven cases (five patients with a single lesion; one with two lesions; one with coarse liver echo-pattern). Among the five patients with a single lesion, one had already been treated by percutaneous ethanol injection therapy. There were no complications related to the biopsy procedures. The diagnosis of non-neoplastic thrombosis allowed five new patients to be recruited for percutaneous ethanol injection treatment and allowed it to continue in the patient with portal vein thrombosis occurring after the fifth ethanol injection. The routine use of ultrasound-guided fine-needle biopsy of portal vein thrombosis yields an accurate diagnosis of the nature of the thrombus and can improve the selection for percutaneous ethanol injection treatment of patients with cirrhosis with hepatocellular carcinoma lesions.     

Radiofrequency ablation improves prognosis compared with ethanol injection for hepatocellular carcinoma < or =4 cm

BACKGROUND & AIMS: The aim of this study was to compare the clinical outcome of percutaneous radiofrequency (RF) ablation, conventional percutaneous ethanol injection (PEI), and higher-dose PEI in treating hepatocellular carcinoma (HCC) 4 cm or less. METHODS: A total of 157 patients with 186 HCCs 4 cm or less were randomly assigned to 3 groups (52 patients in the conventional PEI group, 53 in the higher-dose PEI group, and 52 in the RF group). Clinical outcomes in terms of complete tumor necrosis, overall survival, local tumor progression, additional new tumors, and cancer-free survival were compared across 3 groups. RESULTS: The rate of complete tumor necrosis was 88% in the conventional PEI group, 92% in the higher-dose PEI group, and 96% in the RF group. Significantly fewer sessions were required to achieve complete tumor necrosis in the RF group than in the other 2 groups (P < .01). The local tumor progression rate was lowest in the RF group (vs the conventional PEI group, P = .012; vs the higher-dose PEI group, P = .037). The overall survival rate was highest in the RF group (vs the conventional PEI group, P = .014; vs the higher-dose PEI group, P = .023). The cancer-free survival rate was highest in the RF group (vs the conventional PEI group, P = .019; vs the higher-dose PEI group, P = .024). Multivariate analysis determined that tumor size, tumor differentiation, and the method of treatment (RF vs both methods of PEI) were significant factors in relation to local tumor progression, overall survival, and cancer-free survival. CONCLUSIONS: The results show that RF ablation yielded better clinical outcomes than conventional and higher-dose PEI in treating HCC 4 cm or less.     

Outcome of transarterial chemoembolization monotherapy, and in combination with percutaneous ethanol injection, or radiofrequency ablation therapy for hepatocellular carcinoma

Aim:  Hepatocellular carcinoma (HCC) is one of the most commonly occurring malignances worldwide. Curative therapies such as resection, percutaneous ethanol injection (PEI) and radiofrequency ablation (RFA) have been applied to patients with early-stage HCC. Patients with more advanced cancers require local or systemic therapies. We present the results of our retrospective review conducted to evaluate whether transarterial chemoembolization (TACE) alone and combined TACE with percutaneous ablation for HCC exhibited superior efficacy to palliative treatment.
Methods:  The effects of TACE and of the combined therapies (TACE + PEI or TACE + RFA) on the long-term survival rates were evaluated in 268 untreated HCC patients by various statistical analyses.
Results:  The cumulative survival rates in the TACE alone group were significantly superior to those in the palliative treatment group. Further, the cumulative survival rates in the combined TACE + PEI/RFA group were significantly superior to those in the TACE alone group. When the comparison among the groups was restricted to patients with two or three tumors fulfilling the Milan criteria, significantly greater prolongation of survival was observed in the combined TACE + PEI/RFA group than in the PEI/RFA alone group.
Conclusions:  The aforementioned treatment modalities yielded greater improvements of the survival rate and survival duration as compared to palliative treatment in HCC patients. Furthermore, in terms of the effect on the survival period, combined TACE + PEI/RFA therapy was more effective than TACE monotherapy, and also more effective than PEI or RFA monotherapy in cases with multiple tumors fulfilling the Milan criteria.     

Locoregional treatments for hepatocellular carcinoma

Improvements in diagnostic techniques have enhanced our understanding of the natural history of hepatocellular carcinoma (HCC). This has facilitated a proper evaluation of the available treatment options for this neoplasm through both phase II studies and randomized controlled trials. Surgical resection and liver transplantation constitute the first two radical options, and when they are contra-indicated, patients may benefit from percutaneous ethanol injection or thermal ablation by radiofrequency current. These options may also achieve a complete response and constitute the last potentially radical therapies for small HCC. In contrast, for large multinodular tumours, the available treatment options have not been shown to improve survival. Arterial embolization with or without associated chemotherapy has been widely used. However, randomized controlled trials have failed to show a survival benefit, emphasizing the need to develop new treatment strategies.     

Intra-arterial carbon dioxide-enhanced ultrasonogram of hepatocellular carcinoma treated by transcatheter arterial embolization and percutaneous ethanol injection therapy

The purpose of this study was to investigate the value of carbon dioxide-enhanced ultrasonography (CO₂-US) in the evaluation of viable hepatocellular carcinomas (HCC) which were treated by transcatheter arterial embolization (TAE), percutaneous ethanol injection (PEI), or a combination treatment (TAE and PEI). Forty-one patients with 66 HCC were included in the study. They underwent CO₂-US and angiography were performed in all tumours after they were treated by TAE, PEI or a combination treatment. Forty-six tumours were positively enhanced by CO₂-US and 40 of them were positive by angiography. These 46 tumours were proved to be viable tumours either by biopsy or by follow-up studies. The positive predictive value was 100% for CO₂-US and 87.8% in angiography. Twenty tumours were negative by CO₂-US and these were also negative by angiography. Carbon dioxide-enhanced ultrasonography is a more reliable method for detecting the viable portion of the treated HCC compared with conventional angiography.