• caudate lobe of liver
• microwave ablation laparoscopic colorectal liver metastases liver lesions

Liver cancer is a growing problem around the world. Drugs for liver cancer have limited effect, there are not enough donors for liver transplants and many patients are not candidates for surgery to remove the tumor. In many of these cases, hyperthermia can destroy the tumor in situ with minimally invasive methods such as radiofrequency or microwave ablation. In this paper we review the literature evaluating success rates for complete ablation as judged by actual examination of treated tumors that were removed when patients received a liver transplant. While notable successes can be achieved with ablation, the published studies indicate both that complete treatment is not as common as thought and that imaging methods such as computed tomography and magnetic resonance scans do not completely identify residual cancer. There is therefore an important opportunity for improvement in the treatment of this disease.

Radiofrequency ablation (RFA) and microwave ablation (MWA) are the most widely studied and applied ablation techniques for treating primary and secondary liver tumors. These techniques are considered curative for small hepatic tumors, with post-ablation outcomes most commonly assessed by an imaging follow up. However, there is increasing evidence of a discrepancy between radiological and pathological findings when ablated lesions are evaluated following liver resection or liver transplantation. A comprehensive review of the available literature reporting the complete pathological response (cPR) following RFA and MWA was performed to estimate the success rate and identify the factors associated with treatment failure. Following RFA, cPR is reported in 26–96% of tumors compared to 57–95% with MWA. Larger tumor size and vessels larger than 3 mm adjacent to the treated tumor are the most important factors identified by previous studies associated with viable residual tumors after RFA. Correlating post-ablation radiological studies with pathological findings shows that computed tomography (CT) and magnetic resonance imaging (MRI) have low sensitivity but high specificity for detecting residual viable or recurrent hepatocellular carcinoma (HCC) tumors. There are promising recent reports combining multiprobe ablation techniques with three-dimensional treatment planning software and stereotactic-aiming instrumentation to achieve more than 90% cPR in both small and large HCC tumors. In conclusion, the reported success for achieving cPR in HCC following RFA and MWA is highly variable in different studies and decreases with increasing lesion size and unfavorable tumor characteristics. Very few studies have reported a high rate of cPR. As these studies are single-center and retrospective, they need to be further validated and reproduced in other clinical settings.

• hepatocellular carcinoma
• histopathology
• microwave ablation
• radiofrequency ablation
• thermal ablation

• Segmentation software
• ablation zone
• ellipticity index
• liver
• microwave ablation
• semi-automatic

• HCC
• local control
• microwave ablation
• minimally invasive therapy

• Efficacy
• Hepatocellular carcinoma
• Liver metastasis
• Microwave ablation
• Radiofrequency ablation

• Female
• Humans
• Liver Neoplasms/mortality
• Liver Neoplasms/radiotherapy
• Male
• Microwaves/therapeutic use
• Radiofrequency Ablation/methods
• Survival Analysis

• hypertonic-saline-enhanced electrodes
• liver radiofrequency ablation
• porcine liver
• sodium chloride

This research is concerned with microwave ablation analyses using a 2.45 GHz four-tine (4T) antenna for hepatic cancer tissue. In the study, three-dimensional finite-element models were utilized to examine the tissue temperature distributions during and after MW ablation. A preliminary study was first carried out with regard to the specific absorption rates along the 4T antenna insertion depths and the temperature distributions inside the solid and porous liver models with either 3 cm-in-diameter tumor or 5 cm-in-diameter tumor. Based on the preliminary results, the porous models were further examined for the effect of varying blood flow velocities (0–200 cm/s) with a 1 cm-in-diameter blood vessel next to the antenna and also for the effect of vessel-antenna locations (0, 0.8, and 1.3 cm) with a constant blood flow velocity of 16.7 cm/s. All scenarios were simulated under temperature-controlled mode (90°C). The findings revealed that the blood flow velocity and vessel location influence the ablation effectiveness and that increased blood flow inhibits heat transfer to the vessel wall. At the nearest and farthest vessel-antenna locations (0 and 1.3 cm), approximately 90.3% and 99.55% of the cancer cells were eradicated except for the areas adjacent to the vessel. In addition, total tissue thermal displacement is 5.9 mm which is 6.59% of the total length of the overall model.

• ablation
• interventional radiology
• liver tumors
• microwave

• Ablation
• Electroporation
• Microwave
• Radiofrequency
• Tumor

• Cryoablation
• Liver model
• Microwave ablation
• Porcine model

Hepatic resection (HRx) or radiofrequency ablation may be carried out as the first-line treatment of hepatocellular carcinoma (HCC). However, we have used intraoperative microwave ablation, named microwave coagulo-necrotic therapy (MCN) as part of our strategy for the treatment of HCCs for more than 15 years. Here we describe the treatment outcomes achieved at our institution as a high-volume center for microwave ablation.

Between July 1994 and December 2010, 719 consecutive patients received MCN as their initial therapy for HCC (mean tumor size 26.9 mm, mean number of lesions 2.51) at our institute. The therapeutic survival effect, local tumor progression, and overall recurrence were prospectively evaluated and statistically analyzed.

The 1-, 3-, 5-, 7-, and 10-year overall survival rates of all 719 patients were 97.7, 79.8, 62.1, 45.3, and 34.1 %, respectively. Thirty percent of the patients had Child–Pugh class B cirrhosis and the 5-year survival rate of these patients was 46.6 %. The 5-year survival of patients with ≥4 lesions (n = 168) was 49.6 % and that of patients meeting the Milan criteria (n = 470) was 70.9 %. The 1-, 3-, 5-, 7-, and 10-year overall survival rates for 390 patients treated with MCN who had ≤3 lesions with diameter ≤3 cm were 97.9, 85.1, 70.0, 57.1, and 43.0 %. No significant differences were found between the overall survival rates after MCN and the overall survival rates in 34 patients treated with HRx during the same period at our institute and under the same (P = 0.3592), nor were there any differences in disease-free survival (P = 0.3496) and local recurrence rates between the MCN and HRx groups (P = 0.5926).

MCN is effective for the locoregional control of HCC, with results comparable to those of HRx. MCN should be considered as one of the first-choice treatments for HCC, even for patients with poor liver function or multiple lesions.

Numerous techniques developed in medicine require careful evaluation to determine their indications, limitations and potential side effects prior to their clinical use. At present this generally involves the use of animal models which is undesirable from an ethical standpoint, requires complex and time-consuming authorization, and is very expensive. This process is exemplified in the development of hepatic ablation techniques, starting experiments on explanted livers and progressing to safety and efficacy studies in living animals prior to clinical studies. The two main approaches used are ex vivo isolated non-perfused liver models and in vivo animal models. Ex vivo non perfused models are less expensive, easier to obtain but not suitable to study the heat sink effect or experiments requiring several hours. In vivo animal models closely resemble clinical subjects but often are expensive and have small sample sizes due to ethical guidelines. Isolated perfused ex vivo liver models have been used to study drug toxicity, liver failure, organ transplantation and hepatic ablation and combine advantages of both previous models.

• Liver
• Ablation
• Experiment
• Ex vivo
• In vivo
• Perfusion

Microwaves (MW) technology is an ablative treatment alternative to radiofrequency (RF) for early stages of hepatocellular carcinoma (HCC) in cirrhotic patients not suitable for surgical resection. It is well known that HCC lesions ≥ 30 mm treated by RF show a high rate of local tumor progression because of residual of unablated neoplastic tissue.

Aim of this study was to describe a limited experience of MW ablation (9 cirrhotic patients with medium size HCC: 11 lesions, 31 - 50 mm in diameter) treated from June 2009 to May 2010 by one of currently marketed western MW ablation systems and followed up for 2 years. Primary end-point was the probability of local tumor progression at 24 months; secondary end-point was the safety of the procedure.

Radiological response after a single session and re-evaluation of local tumor progression along the time were performed by contrast enhanced computed-tomography at months 1-8-12-24. Early effectiveness rate was 90.1 %. The cumulative incidence of local tumor progression at 1 and 2 years were 36.4% (95% CI 11.2 - 62.7) and 57.6% (95% CI 23.6 - 81.0). We observed a single minor complication of the procedure.

In conclusion, MW ablation system “Amica” has a high rate of primary effectiveness rate but residual of unablated neoplastic tissue induce local tumor progression in about half of the cases during the following 2 years.

• Hepatocellular carcinoma
• Microwave percutaneous ablation
• Progression
• Tumor

• microwave ablation
• liver
• operative

• colour doppler
• microwave ablation
• liver
• tumour

• Animals
• Cattle
• Electrocoagulation/methods
• Liver/diagnostic imaging
• Liver/surgery
• Microwaves
• Necrosis
• Swine
• Time Factors
• Ultrasonography, Doppler, Color
• Ultrasonography, Interventional/methods

Even with the advent of laparoscopic techniques for liver tumours, classic resections still represent a major undertaking for numerous liver lesions. The avoidance of surgery using ablative techniques has been the aim for over 20 years. Large volumes can now be rapidly treated with low morbidity with the many technical developments and modifications of the delivery probes. Despite these advances recurrences rates remain high with all of the presently available techniques. The biological and pathophysiological basis underlying may help explain their limitations and are important in understanding where they may be appropriately applied and ways in which they may be improved in the future.

• Thermal ablation
• Radiofrequency
• Liver tumors
• Microwaves
• Cryotherapy
• Tumor palliation