Treatment of hepatocellular carcinoma: value of percutaneous microwave coagulation

Interventional oncology of liver tumors: how it all started and where are we now

Liver was the very first organ for which interventional procedures were applied for the local treatment of primary and secondary malignancies. In this paper, the history of Interventional Oncology of liver, from the very beginning to the current situation, is summarized, including both percutaneous and intravascular procedures, and together with the evolution of the techniques for image guidance. The main ongoing developments, such as new techniques, combined interventional treatments and association of local interventions with new drugs are briefly described, too.

Physiological Motion Reduction Using Lagrangian Tracking for Electrode Displacement Elastography

Minimally invasive treatments such as microwave ablation (MWA) have been growing in popularity for extending liver cancer survival rates in patients, when surgery is not an option. As a non-ionizing, real-time alternative to contrast-enhanced computed tomography, electrode displacement elastography (EDE) has shown promise as an imaging modality for MWA. Despite imaging efficacy, motion artifacts caused by physiological motion result in unintended speckle pattern variance, thereby inhibiting consistent and accurate ablated region visualization. To combat these unavoidable motion artifacts, a Lagrangian deformation tracking (LDT) approach based on freehand EDE was developed to track tissue movement and better define tissue properties. For validating LDT efficacy, a spherical inclusion phantom as well as seven in vivo data sets were processed, and strain tensor images were compared with identical time sampled images estimated using a traditional Eulerian approach. In vivo results revealed greater consistency among visualized LDT strain tensor images, with segmented ablated regions exhibiting standard deviation reductions of up to 98% when compared with Eulerian strain tensor images. Additionally, Lagrangian strain tensor images provided Dice coefficient improvements up to 25%, and success rates improved from approximately 50% to nearly 100% for ablated region visualization.

Current State of Tumor Ablation Therapies

The most common primary liver malignancy, hepatocellular carcinoma (HCC), has a high likelihood of mortality, and much effort into early detection and treatment has occurred. Multiple staging systems have surfaced of which some guide treatment. Curative intent is a goal of early-staged HCC treatment, and this can be achieved with surgical resection, liver transplantation, and minimally invasive percutaneous therapies such as tumor ablation. Many of the newer ablation techniques have evolved from shortcomings of prior methods which have resulted in an expanded number of applications for tumor ablation. Our review focuses on current mainstream image-guided percutaneous ablation modalities which are commonly performed as an alternative to surgery.

Delineation of Post-Procedure Ablation Regions with Electrode Displacement Elastography with a Comparison to Acoustic Radiation Force Impulse Imaging

We compared a quasi-static ultrasound elastography technique, referred to as electrode displacement elastography (EDE), with acoustic radiation force impulse imaging (ARFI) for monitoring microwave ablation (MWA) procedures on patients diagnosed with liver neoplasms. Forty-nine patients recruited to this study underwent EDE and ARFI with a Siemens Acuson S2000 system after an MWA procedure. On the basis of visualization results from two observers, the ablated region in ARFI images was recognizable on 20 patients on average in conjunction with B-mode imaging, whereas delineable ablation boundaries could be generated on 4 patients on average. With EDE, the ablated region was delineable on 40 patients on average, with less imaging depth dependence. Study of tissue-mimicking phantoms revealed that the ablation region dimensions measured on EDE and ARFI images were within 8%, whereas the image contrast and contrast-to-noise ratio with EDE was two to three times higher than that obtained with ARFI. This study indicated that EDE provided improved monitoring results for minimally invasive MWA in clinical procedures for liver cancer and metastases.

Adverse effects of irreversible electroporation of malignant liver tumors under CT fluoroscopic guidance: a single-center experience

PURPOSE

We aimed to describe the frequency of adverse events after computed tomography (CT) fluoroscopy-guided irreversible electroporation (IRE) of malignant hepatic tumors and their risk factors.

METHODS

We retrospectively analyzed 85 IRE ablation procedures of 114 malignant liver tumors (52 primary and 62 secondary) not suitable for resection or thermal ablation in 56 patients (42 men and 14 women; median age, 61 years) with regard to mortality and treatment-related complications. Complications were evaluated according to the standardized grading system of the Society of Interventional Radiology. Factors influencing the occurrence of major and minor complications were investigated.

RESULTS

No IRE-related death occurred. Major complications occurred in 7.1% of IRE procedures (6/85), while minor complications occurred in 18.8% (16/85). The most frequent major complication was postablative abscess (4.7%, 4/85) which affected patients with bilioenteric anastomosis significantly more often than patients without this condition (43% vs. 1.3%, P = 0.010). Bilioenteric anastomosis was additionally identified as a risk factor for major complications in general (P = 0.002). Minor complications mainly consisted of hemorrhage and portal vein branch thrombosis.

CONCLUSION

The current study suggests that CT fluoroscopy-guided IRE ablation of malignant liver tumors may be a relatively low-risk procedure. However, patients with bilioenteric anastomosis seem to have an increased risk of postablative abscess formation.

Post-Procedure Evaluation of Microwave Ablations of Hepatocellular Carcinomas Using Electrode Displacement Elastography

Microwave ablation has been used clinically as an alternative to surgical resection. However, lack of real-time imaging to assess treated regions may compromise treatment outcomes. We previously introduced electrode displacement elastography (EDE) for strain imaging and verified its feasibility in vivo on porcine animal models. In this study, we evaluated EDE on 44 patients diagnosed with hepatocellular carcinoma, treated using microwave ablation. The ablated region was identified on EDE images for 40 of the 44 patients. Ablation areas averaged 13.38 ± 4.99 cm² on EDE, compared with 7.61 ± 3.21 cm² on B-mode imaging. Contrast and contrast-to-noise ratios obtained with EDE were 232% and 98%, respectively, significantly higher than values measured on B-mode images (p < 0.001). This study indicates that EDE is feasible in patients and provides improved visualization of the ablation zone compared with B-mode ultrasound.

CT Appearance of Hepatocellular Carcinoma after Locoregional Treatments: A Comprehensive Review

Hepatocellular carcinoma (HCC) is a major health problem worldwide, affecting more than 600,000 new patients per year. Curative treatments are available in a small percentage of patients, while most of them present in stages requiring locoregional treatments such as thermoablation, transarterial chemoembolization, and/or radioembolization. These therapies result in specific imaging features that the general radiologist has to be aware of in order to assess the response to treatment and to correctly manage the follow-up of treated patients. Multiphasic helical computed tomography has become a popular imaging modality for detecting hypervascular tumors and characterizing liver lesions. On this basis, many staging and diagnostic systems have been proposed for evaluating response to all different existing strategies. Radiofrequencies and microwaves generate thermoablation of tumors, and transarterial chemoembolization exploits the double effect of the locoregional administration of drugs and embolizing particles. Eventually radioembolization uses a beta-emitting isotope to induce necrosis. Therefore, the aim of this comprehensive review is to analyze and compare CT imaging appearance of HCC after various locoregional treatments, with regard to specific indications for all possible procedures.

In vivo thermal ablation monitoring using ultrasound echo decorrelation imaging

Previous work indicated that ultrasound echo decorrelation imaging can track and quantify changes in echo signals to predict thermal damage during in vitro radiofrequency ablation (RFA). In the in vivo studies reported here, the feasibility of using echo decorrelation imaging as a treatment monitoring tool was assessed. RFA was performed on normal swine liver (N = 5), and ultrasound ablation using image-ablate arrays was performed on rabbit liver implanted with VX2 tumors (N = 2). Echo decorrelation and integrated backscatter were computed from Hilbert transformed pulse-echo data acquired during RFA and ultrasound ablation treatments. Receiver operating characteristic (ROC) curves were employed to assess the ability of echo decorrelation imaging and integrated backscatter to predict ablation. Area under the ROC curves (AUROC) was determined for RFA and ultrasound ablation using echo decorrelation imaging. Ablation was predicted more accurately using echo decorrelation imaging (AUROC = 0.832 and 0.776 for RFA and ultrasound ablation, respectively) than using integrated backscatter (AUROC = 0.734 and 0.494).

Percutaneous microwave ablation for liver cancer adjacent to the diaphragm

PURPOSE

The aim of the study was to prospectively evaluate the safety and effectiveness of percutaneous microwave (MW) ablation for liver cancer adjacent to the diaphragm.

MATERIALS AND METHODS

From May 2005 to June 2008, 89 patients with 96 hepatic lesions adjacent to the diaphragm (the shortest distance from the lesion margin to the diaphragm less than 5 mm), who underwent ultrasound (US)-guided percutaneous MW ablation, were included in the study group. A total of 100 patients with 127 hepatic lesions not adjacent to the diaphragm (the shortest distance from the lesion to the diaphragm and the first or second branch of the hepatic vessels more than 10 mm), who underwent US-guided percutaneous MW ablation, were included in the control group. During the ablation the temperature of marginal ablation tissue proximal to the diaphragm was monitored and controlled at 50°-60°C for more than 10 min in the study group. We compared the results of ablation between the two groups.

RESULTS

A total of 91 of 96 tumours (94.8%) in the study group and 123 of 127 tumours (96.9%) in the control group achieved complete ablation (P > 0.05). Local tumour progression was found in 18 of 96 tumours (18.8%) in the study group and 21 of 127 tumours (16.5%) in the control group during follow-up after MW ablation (P > 0.05). No major complications occurred in either group.

CONCLUSIONS

Under strict temperature monitoring, percutaneous MW ablation is safe and can achieve a high complete ablation rate for the treatment of hepatic tumours adjacent to the diaphragm.

Development of a highly efficient implanted thermal ablation device: in vivo experiment in rat liver

OBJECTIVES

To evaluate an implanted thermal ablation device that can be heated with high efficiency using a resonant circuit as the implant.

METHODS

16 rats were used. The implants, adjusted at a resonance frequency of 4 MHz, were fixed on the surface of the liver of rats under laparotomy. In 14 of 16 rats, an alternating magnetic field (AMF) was applied for 6 min with an output of 300 W from outside the body using a ferrite core applicator. The implant temperature during AMF exposure was measured. The 14 rats were divided into 5 groups, depending on time from AMF application until they were sacrificed (1 h, 1 day, 3 days, 7 days and 1 month after application). Two rats not exposed to AMF were used as controls. Livers were removed and evaluated; the cross-sectional area and width of the ablated region were measured.

RESULTS

During AMF exposure, the implant temperature rose to 127.8±39.3 °C (mean±standard deviation). The cross-sectional area of the ablated region was largest after 1 day and tended to decrease with time. The widths of the ablated region were 4.87±0.22 mm, 4.15±0.36 mm, 3.67±0.58 mm and 3.24±0.16 mm in the 1 day, 3 day, 7 day and 1 month groups, respectively. No significant differences (p<0.05) were seen in either cross-sectional area or width of the ablated region.

CONCLUSION

Sufficient heat for ablation was obtained in vivo using a newly developed implanted thermal ablation device. This device may be a new option for thermal ablation therapy.

Microwave coagulation using a perfusion microwave electrode: Preliminary experimental study using ex vivo and in vivo liver

To assess the coagulation capability of a perfusion microwave electrode (PME) as a key component of microwave coagulation therapy, a preliminary experimental study was performed using ex vivo and in vivo livers. For a microwave electrode, a PME was employed. Using a PME, saline was passed through the electrode and injected continuously into the target tissue. Using an ex vivo bovine liver, the range of tissue coagulation was measured for various volumes of infused saline and microwave outputs. Using an in vivo porcine liver, the efficiency of coagulation by a PME was compared with that of radiofrequency ablation (RFA) using a cool-tip needle. In an ex vivo bovine liver, the range of tissue coagulation increased as the flow rate of saline increased. In the in vivo porcine liver, the range of coagulation was similar to that found in the ex vivo bovine liver. With a PME under conditions of a microwave output of 80 W, a flow rate of 3 ml/min and irradiation time of 5 min, the range of coagulation was 44.8±2.8 mm [maximum vertical diameter: (a)] x 31.2±2.4 mm [maximum transverse diameter: (b)]. The range of RFA (cool-tip needle) at 12 min was 46.0±2.0 mm (a) x 30.2±2.0 mm (b). With only 5 min of microwave irradiation, the use of a PME enabled induction of the same range of coagulation that was obtainable by RFA for 12 min. In comparison with microwave coagulation without saline infusion, the use of a PME made it possible to extend the range of tissue coagulation to a range equal to that of RFA in a short time. Microwave coagulation using a PME may be one of the suitable tissue coagulation systems for local ablation treatment.

Percutaneous ankaferd injection to in vivo liver tissue in comparison to ethanol in an experimental rat model

AIM

Percutaneous ethanol injection is an established management of nonresectable hepatocellular carcinoma (HCC) because of its high effectiveness and minimal invasiveness. However, ethanol has many disadvantages like less anti-tumoral necrotic effectivity, unequal permeation and local diffusion. The aim of this study is to compare hepatic tissue effects of percutaneous Ankaferd Blood Stopper (ABS) injection in comparison to ethanol in rat liver tissue.

MATERIALS AND METHODS

Twenty-one healthy rats were randomly divided into three groups, each containing seven animals. Group I received 0.1cm(3) percutaneous injection of isotonic saline, group II received 0.1cm(3) ethanol, and group III received 0.1cm(3) ABS. At the 5th day, the livers were dissected. Macroscopic and histopathological features of the liver lesions were documented.

RESULTS

All the rats in the group I and II lived during study period; one rat died in the ABS group. Macroscopic pale yellow coloration was observed within 2 minutes in both ethanol and ABS groups. Necrosis was observed in both Group II and III. The necrosis volumes of the ABS group (volume: 1475.00 ± 697.16 cm(3)) were significantly higher than the ethanol group (volume: 60.714 ± 26.277 cm(3)) (P=0.002). In the histopathological analyses of the liver tissues, aggregated erythrocytes in sinusoidal spaces and bile duct proliferation have been detected in ABS group.

CONCLUSION

ABS may be considered as a possible percutaneous treatment in HCC instead of or as an alternative to ethanol. With its unique hemostatic actions and the safety profile, ABS can be considered as a useful novel agent for the percutaneous therapy of HCC instead of ethanol in the future.

Radiofrequency ablation of hepatocellular carcinoma

Radiofrequency ablation (RFA), usually performed under percutaneous ultrasound guidance, is considered the gold standard among minimally invasive therapies. On the strength of some recent randomized trials, its indications include operable patients with small hepatocellular carcinoma and inoperable patients with more advanced disease also in combination with other therapies. RFA has lower complication rates and costs less than surgery.

Thermochemical ablation in an ex-vivo porcine liver model using acetic acid and sodium hydroxide: proof of concept

PURPOSE

To establish proof of concept in tissue, using the exothermic neutralization reaction of acetic acid and sodium hydroxide in ex vivo porcine liver and to conduct an initial probe into the relationships of volume and concentration of reagents to temperatures and the areas affected.

MATERIALS AND METHODS

A total of 0.5 mL or 2 mL of either 5 mole/L or 10 mole/L acid and base solutions was injected simultaneously into the periphery of ex vivo porcine liver using a prototype injection device. Tissue temperature was recorded at the injection site for 5 minutes using a type T thermocouple temperature probe inserted parallel to and near the tip of the injection device. The injections were repeated for infrared thermography, and ablated tissues were sectioned quickly and imaged. A gross photograph was captured in each case to provide correlation.

RESULTS

Maximum temperatures (17°C baseline) ranged from 42.1° ± α3.34°C to 61.7° ± α10°C (P<.05) when injecting 0.5 mL of 5 mole/L reactants and 2 mL of 10 mole/L reactants, respectively. The maximum temperature measured by infrared imaging ranged from 31°-47°C. Using an infrared viewing scale from 19°-40°C, the cross-sectional area of tissue heating above baseline measured from 1.07 cm(2)± 0.45 to 4.95 cm(2)± 0.28 (P <05).

CONCLUSIONS

The reaction of acetic acid and sodium hydroxide releases significant heat energy at the site of injection, and histologic changes are consistent with coagulation necrosis. Increased reagent concentration and volume were associated with larger temperature changes and larger areas of hyperthermia at gross pathology and infrared imaging.

Feasible temperature of percutaneous microwave ablation of dog liver abutting the bowel

PURPOSE

This study used a dog model to determine the optimal temperature of percutaneous microwave ablation that causes complete necrosis of liver but not the adjacent bowel, supporting the use of this method to specifically and effectively treat liver tumour abutting the bowel.

MATERIALS AND METHODS

Ultrasound-guided percutaneous microwave ablation of liver abutting the bowel was performed on healthy adult dogs. Temperature of the ablation margin was monitored and controlled through inserted thermal monitoring needles. Dogs were divided into three groups and received microwave ablation at 75-95°C, 65-75°C, or 55-65°C. Imaging and histological examination were used to evaluate the damage of the bowel adjacent to the ablated liver.

RESULTS

Within one hour of treatment, the bowel adjacent to the ablated liver was seriously burned in the group receiving 75-95°C microwave ablation. Inflammation and congestion were found in the submucosa of the bowel in the group receiving 65-75°C microwave ablation. Minor inflammation was found in the mucosa of the bowel in the group receiving 55-65°C microwave ablation. Moreover, in the group receiving 55-65°C microwave ablation, ablated liver areas were covered with omenta, and histological examination revealed inflammatory reaction of the omenta 28 days after ablation.

CONCLUSIONS

Microwave ablation at 55-65°C for 6 min is preferred for ablation of liver tissue abutting the bowel in dogs. These findings may provide some valuable reference for percutaneous microwave ablation of human liver tumour adjacent to the bowel.

Prevention of tumour cell dissemination in diagnostic needle procedures

BACKGROUND

A side effect of diagnostic needle biopsies is the possibility to disseminate tumour cells into the needle track, which may cause concern in certain malignant tumour types.

METHODS

In order to prevent tumour cell dissemination we developed a technology that uses radiofrequency (RF) pulses to sterilise the needle track and denaturate tumour cells. To determine feasibility, we applied this technology to fine needle aspiration biopsy (FNAB) and used breast cancer as a model tumour. Routine FNAB was performed in 88 patients with adenocarcinoma and blood droplets passing the skin orifice were cytomorphologically analysed for the presence of tumour cells.

RESULTS

The analysis showed the presence of tumour cells in 65/88 cases (74%). When using an experimental anti-seeding device in a subset of patients viable tumour cells were found in 0/31 cases (P<0.001). In all 31 patients blood passing the skin orifice was sparse. No degrading effect on the cytological sample inside the needle was detected and pain caused by the RF pulses was comparable to that of the biopsy procedure itself.

CONCLUSION

The herein presented method has the potential to prevent the dissemination of viable tumour cells in the needle track and minimize bleeding without additional pain or degradation of the aspirate.

Chemoembolization for the treatment of large hepatocellular carcinoma

PURPOSE

To retrospectively evaluate the efficacy of chemoembolization for inoperable hepatocellular carcinoma (HCC) tumors larger than 5 cm in diameter.

MATERIALS AND METHODS

Chemoembolization was performed in 30 patients with HCCs with a largest diameter of more than 5 cm with three or fewer lesions and no portal vein tumor thrombus. The mean maximum tumor diameter was 7.7 cm +/- 2.4. When the tumor was extremely large and had multiple feeding arteries, stepwise chemoembolization sessions at intervals of 3-10 weeks were performed. In addition, extrahepatic collateral supply was identified and embolized. Local therapeutic effects, survival rates, and complications were analyzed.

RESULTS

The mean follow-up period was 33.8 months +/- 24.1. One to 13 chemoembolization sessions (mean, 4.0 sessions +/- 3.0) were performed in each patient. Additionally, 62 collateral vessels were embolized in 21 patients, including 22 vessels in 14 patients at the initial procedure. Early tumor response rate 2-3 months after treatment was 43.3% by Response Evaluation Criteria In Solid Tumors. Complete radiologic response was achieved in 19 patients. Eleven patients died between 4 and 61 months after treatment (mean, 27.2 months +/- 21.8), including four deaths unrelated to hepatic causes. Nineteen patients have survived for 6-103 months (mean, 37.5 months +/- 25.2). Overall and progression free-survival rates at 1, 3, and 6 years were 82.3% and 66.0%, 73.9% and 57.6%, and 32.9% and 34.2%, respectively. Three infectious complications developed and were managed by interventions.

CONCLUSIONS

Chemoembolization was effective for large HCCs, although there is a risk of infectious complications after the procedure.

Targeted hyperthermia using metal nanoparticles

Despite the use of hyperthermia to treat cancer for thousands of years, the challenge of only heating malignant cells remains daunting. In pre-clinical and early clinical trials, metal nanoparticles induce hyperthermic cytotoxicity when exposed to near-infrared radiation or radiofrequency fields. We discuss the emerging roles of nanoparticles, especially gold, in the hyperthermic treatment of cancer. In addition, we discuss the similarities of radiofrequency ablation and nanoparticle mediated cytotoxicity.

Contrast-enhanced sonography with abdominal virtual sonography in monitoring radiofrequency ablation of hepatocellular carcinoma

BACKGROUND

Contrast-enhanced CT is regarded as the gold standard for monitoring radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC). Recently, 3-dimensional volume data from CT have been used to create cross-sectional multiplanar reconstruction images. Using this technique, we can reconstruct 2-dimensional CT images identical in orientation to ultrasound (US) images, which we call virtual sonographic (VUS) images. The present prospective randomized control trial compared the number of CT scans needed to assess the efficacy of RFA of HCC using VUS-contrast-enhanced ultrasonography (CEUS) versus CT.

METHOD

Subjects comprised 50 patients (50 HCCs) treated with US-guided RFA between May 2005 and August 2006, randomized to undergo assessment by CT (Group 1; 25 HCC nodules) or VUS-CEUS (Group 2; 25 HCC nodules). All patients were followed for 1 year. Primary endpoint was whether the number of CT scans could be reduced using VUS-CEUS.

RESULT

Mean number of CT scans required was 1.64 +/- 0.7 in Group 1 and 1.1 +/- 0.2 in Group 2 (p < 0.001).

CONCLUSION

VUS-CEUS can be used to assess the efficacy of HCC of RFA, with the potential to reduce the number of CT scans required for that purpose.

Phantom experimental study on microwave ablation with a water-cooled antenna

Microwave ablation therapy using a water-cooled antenna was studied experimentally in a phantom. The development of the heating pattern induced by the microwave antenna was determined from the thermocouple-measured temperature field, and the influence of the cooling water flow within the antenna on temperature distribution and heating pattern was investigated. The shape of the heating pattern was pear-like, and the enlarging rate of the heating pattern decreased with heating time. Because of strong cooling effect, the heating pattern in the region with Z < 0 (where Z = 0 represents the position of radiator, Z < 0 and Z > 0 represent the backward direction of the antenna with cooling water and forward direction without water, respectively) was smaller in diameter than that with Z > 0, and the heating pattern with Z < 0 was slightly reduced when the velocity of the cooling water increased. The highest ablative temperature occurred with Z > 0 decreasing. Finally, the specific absorption rate distribution was also determined and investigated analytically. The present results can be helpful in clinical ablation therapy practice and will be applicable to multiple applicators for surgical planning.

Review of Asian experience of thermal ablation techniques and clinical practice

The field of image-guided tumour ablation has gained great attention from Asian physicians because it represents a safe and effective technique for many commonly seen tumours in this population, showing minimal morbidity and excellent local control rates. Based on the current survey data from Asian physicians who are currently performing image-guided tumour ablation, thermal ablation has been mainly performed for patients with unresectable liver tumours. Radiofrequency ablation has replaced many other local ablation techniques such as microwave or ethanol ablation in treating small focal hepatic tumours for the last 5 years. Surgery and transcatheter arterial chemoembolization also have a unique role as curative and palliative treatment options for patients with more extensive tumour burden. Although radiofrequency ablation represents a paradigm shift in local therapy, more sophisticated strategies to enhance the therapeutic efficacy are necessary and more randomized and controlled investigations to estimate its clinical benefit are warranted.

In vivo evaluation of a mechanically oscillating dual-mode applicator for ultrasound imaging and thermal ablation

Unresectable liver tumors are often treated with interstitial probes that modify tissue temperature, and efficacious treatment relies on image guidance for tissue targeting and assessment. Here, we report the in vivo evaluation of an interstitial applicator with a mechanically oscillating five-element dual-mode transducer. After thoroughly characterizing the transducer, tissue response to high-intensity ultrasound was numerically calculated to select parameters for experimentation in vivo. Using perfused porcine liver, B-mode sector images were formed before and after a 120-s therapy period, and M-mode imaging monitored the therapy axis during therapy. The time-averaged transducer surface intensity was 21 or 27 W/cm (2). Electroacoustic conversion efficiency was maximally 72 +/- 3% and impulse response length was 295 +/- 1.0 ns at -6 dB. The depth of thermal damage measured by gross histology ranged from 10 to 25 mm for 13 insertion sites. For six sites, M-mode data exhibited a reduction in gray-scale intensity that was interpreted as the temporal variation of coagulation necrosis. Contrast ratio analysis indicated that the gray-scale intensity dropped by 7.8 +/- 3.3 dB, and estimated the final lesion depth to an accuracy of 2.3 +/- 2.4 mm. This paper verified that the applicator could induce coagulation necrosis in perfused liver and demonstrated the feasibility of real-time monitoring.

Percutaneous microwave ablation of liver cancer adjacent to the gastrointestinal tract

PURPOSE

The purpose of the study was to prospectively evaluate safety and effectiveness of percutaneous microwave ablation under temperature monitoring assisted with ethanol injection for liver cancer abutting gastrointestinal tract.

MATERIALS AND METHODS

One hundred seventy-nine hepatic tumors that underwent percutaneous microwave ablation with curative intention were included. Fifty-three lesions located less than 5 mm from gastrointestinal tract were in gastrointestinal group. One hundred twenty-six lesions located more than 5 mm from hepatic surface and first or second branch of hepatic vessels were in control group. The temperature of marginal ablation tissue proximal to gastrointestinal tract was monitored and controlled to fluctuating between 45 degrees C and 58 degrees C for more than 10 min for tumors in the gastrointestinal group. Ethanol (2-27 ml) was injected into marginal tissue in 33 of 53 lesions of the GI group.

RESULTS

Forty-seven of 53 tumors (88.7%) in the gastrointestinal group and 116 of 126 tumors (92.1%) in the control group achieved complete ablation (p > 0.05). There were neither immediate nor periprocedural complications in both groups. Tumor seeding happened in one of the gastrointestinal group and two of the control group. There was no delayed complication of bile ducts injury.

CONCLUSION

Under strict temperature monitoring, microwave ablation assisted with ethanol injection is safe and achieves a high complete ablation rate for hepatic tumors adjacent to gastrointestinal tract.

Transcatheter arterial chemoembolization or chemoinfusion for unresectable intrahepatic cholangiocarcinoma: clinical efficacy and factors influencing outcomes

BACKGROUND

The role of transcatheter arterial chemoembolization (TACE) or transcatheter arterial chemoinfusion (TACI) for unresectable intrahepatic cholangiocarcinoma (ICC) has recently been questioned. The aim of the study was to evaluate the clinical efficacy of TACE or TACI in patients with unresectable ICC and to identify prognostic factors associated with clinical success.

METHODS

From 1997 to 2007, 49 patients with unresectable ICC were treated with TACE (n = 124) or transcatheter arterial chemoinfusion (TACI) (n = 96). Tumor response was evaluated based on computed tomography scans obtained 1 month to 3 months after TACE or TACI. Factors associated with clinical success were evaluated using multivariate logistic regression analysis. Factors associated with the survival period were evaluated using multivariate Cox regression analysis.

RESULTS

After treatment, 27 (55%) of the patients showed radiographic response. Multivariate analysis confirmed that tumor vascularity (odds ratio [OR], 31.2; P = .002) was the only independent factor associated with radiographic response. The median and mean survival periods in our study patients were 12 and 24 months. Multivariate Cox regression analyses showed that tumor size (OR, 2.64; P = .048), tumor vascularity (OR, 13.5; P < .001), and the Child-Pugh class (OR, 3.65; P = .014) were the independent factors associated with the length of the survival period.

CONCLUSIONS

Hepatic intra-arterial chemotherapy is well tolerated and may be effective to prolong survival of patients with unresectable ICC. Tumor vascularity is significantly associated with radiographic response. Large tumor size, tumor hypovascularity, and Child-Pugh class B were poor prognostic factors for determining the patient survival period.

Effectiveness of real-time virtual sonography-guided radiofrequency ablation treatment for patients with hepatocellular carcinomas

AIM

Real-time virtual sonography (RVS) can synchronize B-mode ultrasound (US) images with multiplanar reconstruction (MPR)-computed tomography (CT) images on the same screen in real time. The purpose of this study was to evaluate the effectiveness of RVS for radiofrequency ablation therapy (RFA) of hepatocellular carcinomas (HCC) in which it was difficult to identify contours or margins by B-mode US.

METHODS

Sixty-three consecutive patients with a solitary HCC of less than 3.5 cm in diameter were enrolled in this study. Thirty-nine patients with HCC clearly detectable by B-mode US underwent conventional RFA, while the remaining 24 with obscure tumor lesions underwent RVS-guided RFA. A follow-up study of RFA treatment was performed every 3 months using enhanced CT imaging of the arterial and portal phase (at least 24 months). The accuracy of needle insertion was confirmed by measuring the gap between the needle insertion line and the center of the tumor from MPR-CT images.

RESULTS

The local recurrence rate of the RVS-guided RFA group was similar to that of the conventional RFA group (8.3% vs 7.7%), despite the difficulty of detecting tumor lesions in the former group. The mean gap between the needle insertion line and the center of the tumor was 1.6 mm (0-3.2 mm) in eight patients treated with RVS-guided RFA.

CONCLUSION

RVS-guided RFA can be useful for treating HCC that are difficult to detect by B-mode US.

Transcatheter arterial chemoembolization: current technique and future promise

Transarterial chemoembolization is the mainstay of catheter based interventional oncologic therapies. This article describes the history of the procedure, selection of appropriate candidates, technical aspects of procedure performance, results, complications, and appropriate follow-up. In addition, the limitations and challenges of the procedure are outlined. Finally, the reader is introduced to novel and promising techniques and devices that hold future promise for transarterial therapy of malignancies.

Radiofrequency ablation of liver adjacent to body of gallbladder: histopathologic changes of gallbladder wall in a pig model

OBJECTIVE

The purpose of our study was to evaluate the histopathologic changes of gallbladder wall surrounding radiofrequency ablation zones in pig livers and to assess the risk factors for thermal injury of gallbladder wall in terms of distance of the electrode, electrode direction in relation to the gallbladder wall, and time of sacrifice of the animal.

MATERIALS AND METHODS

The study was performed in 15 pigs using an internally cooled single electrode with a 1-cm electrically active tip under sonographic guidance. Twenty-three hepatic ablation zones abutting the gallbladder were analyzed in three phases on the basis of the distance of the electrode (group A, 0.5 cm; group B, 1.0 cm), electrode direction (perpendicular or parallel), and time of sacrifice (immediate or delayed [7 days after radiofrequency ablation]). We evaluated the gross changes, the depth of thermal injury, and the grade of abnormal microscopic changes in the gallbladder wall. Data analysis was performed on the basis of the Fisher's exact test.

RESULTS

Discoloration and perforation were more frequent in group A (60%, 6/10, and 20%, 2/10, respectively) than in group B (25%, 2/8, and 0%, respectively, p > 0.05). Perforation was more frequent in the parallel direction and delayed phase (33.3%, 1/3, and 40%, 2/5, respectively) compared with the perpendicular direction and immediate phase (14.3%, 1/7, and 0%, respectively, p > 0.05). Depth of thermal injury showed a significant difference between group A and group B for full-thickness involvement (53.8%, 7/13, versus 0%, respectively, p < 0.05). Abnormal microscopic changes showed that parallel direction and immediate phase were more frequent with full-thickness involvement (71.4%, 5/7, and 71.4%, 5/7, respectively) compared with perpendicular direction and delayed phase (33.3%, 2/6, and 33.3%, 2/6, respectively, p > 0.05).

CONCLUSION

Hepatic radiofrequency ablation abutting the gallbladder can produce substantial thermal injury of the gallbladder wall, including perforation, especially when performed without a safe distance.

Microwave ablation of hepatocellular carcinoma

OBJECTIVE

This article reviews the basic principles, equipment, current therapeutic status and future trends of microwave ablation (MWA) in the treatment of hepatocellular carcinoma (HCC).

METHODS

All articles published in English on MWA or MWA as a treatment for HCC were identified with a PubMed search from the 1990s through June 2007. Papers were reviewed on the technical advances of MWA equipment and the clinical applications of MWA including indications, techniques, therapeutic outcomes, complications and combination therapies.

RESULTS

MWA has several advantages, including high thermal efficiency, higher capability of coagulating blood vessels, faster ablation time, and an improved convention profile. MWA can induce large ablation volumes and yield good local tumor control, especially for small HCC. Larger HCC can also be completely ablated by using more effective antenna or simultaneous application of multiple antennae. Long-term survival comparable to that of surgery was obtained for tumors measuring 4 cm or less. Associated complications appear to be low.

CONCLUSIONS

MWA is a promising minimally invasive technique for the treatment of HCC. Future advances are warranted to improve the therapeutic efficacy.

Conformal radiation therapy for portal vein tumor thrombosis of hepatocellular carcinoma

BACKGROUND AND PURPOSE

The prognosis of patients with portal vein tumor thrombosis (PVTT) from hepatocellular carcinoma (HCC) is poor; without treatment, their survival is less than 3months. We retrospectively evaluated the treatment outcomes of conformal radiation therapy (CRT) in patients with HCC-PVTT.

MATERIALS AND METHODS

Thirty-eight HCC patients with PVTT in whom other treatment modalities were not indicated underwent CRT. The total dose was translated into a biologic effective dose (BED) of 23.4-59.5Gy(10) (median 50.7Gy(10)) as the alpha/beta ratio=10. Predictive factors including the age, performance status, Child-Pugh classification, PVTT size, and BED were evaluated for tumor response and survival.

RESULTS

Complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD) were observed in 6 (15.8%), 11 (28.9%), 17 (44.7%), and 4 (10.5%) patients, respectively. The response rate (CR+PR) was 44.7%. The PVTT size (<30 vs. 30mm) and BED (<58 vs. 58Gy(10)) were significant factors for tumor response. The median survival and 1-year survival rate were 9.6months and 39.4%. The Child-Pugh classification (A vs. B) and BED were significant factors for survival.

CONCLUSIONS

CRT is effective not only for tumor response but also for survival in HCC-PVTT patients in whom other treatment modalities are not indicated.

Radiofrequency ablation of hepatocellular carcinoma in patients with decompensated cirrhosis: evaluation of therapeutic efficacy and safety

OBJECTIVE

Our objective was to determine the therapeutic efficacy and safety of radiofrequency ablation in the treatment of hepatocellular carcinoma (HCC) in patients with decompensated cirrhosis.

SUBJECTS AND METHODS

Nineteen patients with 26 HCC nodules (range, 0.8-5 cm; mean, 1.96 cm) and decompensated liver cirrhosis (mean Child score, 10.7) were treated with radiofrequency ablation using cooled-tip electrodes and a 200-W generator. Radiofrequency ablation was performed under the guidance of sonography or CT. Procedure-related complications, therapeutic efficacy, each patient's survival, changes in blood test results--that is, serum aminotransferase and bilirubin--and changes in the Child score before and after ablation therapy were analyzed. To assess the therapeutic response of the tumor to radiofrequency ablation, we performed contrast-enhanced CT after the procedure and during follow-up.

RESULTS

Complete necrosis without marginal recurrence at the 6-month follow-up was attained in 23 lesions (88.5%). During follow-up (mean, 13.3 months), one patient experienced a remote tumor recurrence in the liver. The median survival time was 12.0 +/- 1.7 months. Two patients died of liver failure--one at 2 months and one at 4 months after treatment. The other patients were followed for at least 6 months (range, 6-28 months; mean, 12 months). The first and second weeks after therapy, the serum aminotransferase and bilirubin levels were significantly higher than were pretreatment levels (p < 0.05). However, 3 weeks after therapy, those figures were nearly restored to the pretreatment levels. The mean Child scores 3 weeks after radiofrequency ablation (10.8) were similar to those before treatment (10.7).

CONCLUSION

Radiofrequency ablation can be used selectively for treatment of HCC in patients with decompensated cirrhosis but has the potential to aggravate the preexisting hepatic dysfunction.

Transcatheter and ablative therapeutic approaches for solid malignancies

The purpose of this article is to present in a concise manner an overview of the most widely used locoregional transcatheter and ablative therapies for solid malignancies. An extensive MEDLINE search was performed for this review. Therapies used for liver cancer were emphasized because these therapies are used most commonly in the liver. Applications in pulmonary, renal, and bone tumors were also discussed. These approaches were divided into catheter-based therapies (such as transcatheter arterial chemoembolization, bland embolization, and the most recent transcatheter arterial approach with drug-eluting microspheres), ablative therapies (such as chemical [ethanol or acetic acid injection]), and thermal ablative therapies (such as radiofrequency ablation, laser induced thermotherapy, microwave ablation, cryoablation, and extracorporeal high-intensity focused ultrasound ablation). A brief description of each technique and analysis of available data was reported for all therapies. Locoregional transcatheter and ablative therapies continue to be used mostly for palliation, but have also been used with curative intent. A growing body of evidence suggests clear survival benefit, excellent results regarding local tumor control, and improved quality of life. Clinical trials are underway to validate these results. Image-guided transcatheter and ablative approaches currently play an important role in the management of patients with various types of cancer-a role that is likely to grow even more given the technological advances in imaging, image-guidance systems, catheters, ablative tools, and drug delivery systems. As a result, the outcomes of patients with cancer undoubtedly will improve.

Usefulness of contrast-enhanced ultrasonography with abdominal virtual ultrasonography in assessing therapeutic response in hepatocellular carcinoma treated with radiofrequency ablation

OBJECTIVE

Contrast-enhanced computed tomography (CECT) is regarded as the gold standard for assessing the efficacy of radiofrequency ablation (RFA) against hepatocellular carcinoma (HCC). We evaluated the efficacy of virtual ultrasonography (VUS) with contrast-enhanced ultrasonography (CEUS) vs. CECT for assessing the response to RFA.

MATERIALS AND METHODS

Study 1: The therapeutic responses in 22 patients with 26 HCC nodules were assessed by CEUS with VUS as well as by CECT. The efficacy of treatment was based on whether the safety margin was greater than 5 mm after RFA. Study 2: In seven patients with seven HCC nodules, the nodules were treated by RFA and the therapeutic efficacy was assessed by CEUS with VUS. The number of RFA sessions was assessed.

RESULTS

Compared with CECT, CEUS with VUS had a specificity of 77%, a sensitivity of 91.6%, and an accuracy of 84%. When the therapeutic response to RFA was analyzed by CECT only, 1.86 +/- 0.69 assessments (mean) were required, while when response was assessed by CEUS with VUS, 1.14 +/- 0.38 CECT assessments were required (P = 0.03).

CONCLUSION

CEUS with VUS is effective in assessing the therapeutic response to RFA of HCC. Moreover, the number of CECT scans required is reduced by this approach.

Technology insight: Image-guided therapies for hepatocellular carcinoma--intra-arterial and ablative techniques

Locoregional techniques have become the mainstay of therapy for patients with unresectable hepatocellular carcinoma (HCC). Such image-guided interventions include catheter-based approaches (transarterial chemoembolization and yttrium-90 radiotherapy) and locoregional ablative techniques, either chemical (percutaneous ethanol injection), or thermal (radiofrequency ablation, laser ablation, microwave ablation and cryoablation). These therapies are mainly utilized for palliation, but have also been used with curative intent. In selected cases, percutaneous interventional treatments have shown good results (5-year survival 40-50%), but, even when chosen as first-line treatment, have not been able to achieve the response rates and outcomes achieved by surgical options (resection or transplantation). New promising image-guided therapies are continuously emerging, as we attempt to improve tumor targeting, minimize hepatic toxicity and ultimately improve quality of life and survival of patients with HCC. With new technologies in imaging and drug delivery becoming available, it is likely that, in the future, patients with HCC will be best treated by a multidisciplinary team approach, utilizing a combination of techniques to improve patient survival. This review outlines the current status of the most commonly used image-guided locoregional interventions in the treatment of patients with HCC, and describes recent research and advances related to image-guided interventions for liver cancer.

Therapeutic response assessment of percutaneous radiofrequency ablation for hepatocellular carcinoma: utility of contrast-enhanced agent detection imaging

PURPOSE

To assess the utility of contrast-enhanced agent detection imaging (ADI) in the assessment of the therapeutic response to percutaneous radiofrequency (RF) ablation in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Ninety patients with a total of 97 nodular HCCs (mean, 2.1+/-1.3 cm; range, 1.0-5.0 cm) treated with percutaneous RF ablation under the ultrasound guidance were evaluated with contrast-enhanced ADI after receiving an intravenous bolus injection of a microbubble contrast agent (SH U 508A). We obtained serial contrast-enhanced ADI images during the time period from 15 to 90 s after the initiation of the bolus contrast injection. All of the patients underwent a follow-up four-phase helical CT at 1 month after RF ablation, which was then repeated at 2-4 month intervals during a period of at least 12 months. The results of the contrast-enhanced ADI were compared with those of the follow-up CT in terms of the presence or absence of residual unablated tumor and local tumor progression in the treated lesions.

RESULTS

On contrast-enhanced ADI, technical success was obtained in 94 (97%) of the 97 HCCs, while residual unablated tumors were found in three HCCs (3%). Two of the three tumors that were suspicious (was not proven) for incomplete ablation were subjected to additional RF ablation. The remaining one enhancing lesion that was suspicious of a residual tumor on contrast-enhanced ADI was revealed to be reactive hyperemia at the 1-month follow-up CT. Therefore; the diagnostic concordance between the contrast-enhanced ADI and 1-month follow-up CT was 99%. Of the 94 ablated HCCs without residual tumors on both the contrast-enhanced ADI and 1-month follow-up CT after the initial RF ablation, five (5%) had CT findings of local tumor progression at a subsequent follow-up CT.

CONCLUSION

Despite its limitations in predicting local tumor progression in the treated tumors, contrast-enhanced ADI is potentially useful for evaluating the early therapeutic effect of percutaneous RF ablation for HCCs.

Seeding from hepatocellular carcinoma after percutaneous ablation: color Doppler ultrasound findings

BACKGROUND

We describe the clinical and color Doppler ultrasound findings in a series of cases of seeding from hepatocellular carcinoma (HCC) observed in patients treated with percutaneous ablation therapy (PAT) over a 15-year period.

METHODS

We reviewed the clinical and imaging records of 12 patients with cirrhosis (nine men and three women, age range 51-82 years, mean age 63 years) that showed neoplastic seeding from HCC occurring after one or more PAT procedures. Five of 12 cases of seeding were observed as a complication of 1080 PAT procedures (0.46%) performed in 545 patients (0.96%) by two of the authors (L.T., G.F.) over a long period (15 years) at different institutions. The other seven patients had been treated with PAT procedures at other institutions and had come to our attention during post-treatment follow-up.

RESULTS

The 12 patients who had seeding nodules had undergone the following PAT procedures: multisession conventional percutaneous ethanol injection (PEI) without anesthesia (four patients), single-session PEI with general anesthesia (three patients), single-session PEI with general anesthesia plus multisession conventional PEI (four patients), and single-session PEI plus radiofrequency ablation (one patient). Seeding nodules ranged from 0.9 to 6.0 cm (mean 1.7 cm). Eleven of 12 seeding nodules appeared as hypervascular hypoechoic nodules with smooth and regular margins and multiple intralesional vascular signals.

CONCLUSIONS

Clinical and imaging findings of seeding from HCC should be recognized by physicians who perform follow-up ultrasound examinations of patients who are treated with PAT. Early diagnosis of seeding can be reliably made by scanning the abdominal wall with small probes in the area where the previous PAT has been performed. Hypoechoic hypervascular pattern of the seeding nodule allows definitive diagnosis.

Liver abscess after percutaneous radiofrequency ablation for hepatocellular carcinomas: frequency and risk factors

OBJECTIVE

The purpose of this study was to clarify the frequency and risk factors of liver abscess formation after percutaneous radiofrequency ablation in patients with hepatocellular carcinoma.

MATERIALS AND METHODS

Over a 4-year period, 603 patients with 831 hepatocellular carcinomas measuring 5 cm or less in maximum diameter who underwent a total of 751 percutaneous radiofrequency ablation procedures were enrolled in this study. We retrospectively reviewed the medical records and analyzed the overall frequency of liver abscess, risk factors for abscess, and clinical features of the patients. The relationships between liver abscess and potential risk factors were analyzed using either generalized estimating equations or multiple logistic regression analysis.

RESULTS

Liver abscess developed in 14 tumors of 13 patients after 13 (13/751 [1.7%]) ablation procedures. Generalized estimating equations and multiple logistic regression analysis of various potential risk factors revealed that preexisting biliary abnormality prone to ascending biliary infection (p = 0.0088), tumor with retention of iodized oil from previous transcatheter arterial chemoembolization (p = 0.040), and treatment with an internally cooled electrode system (p = 0.016) were associated with a significant risk of liver abscess formation. No patient died of liver abscess, and all successfully recovered from liver abscess with parenteral antibiotics and percutaneous clearance of pus.

CONCLUSION

Although liver abscess formation was infrequent in patients who underwent percutaneous radiofrequency ablation for hepatocellular carcinoma, the patients with significant risk factors-preexisting biliary abnormality prone to ascending biliary infection, tumor with retention of iodized oil, and treatment with an internally cooled electrode system-for liver abscess formation should be closely monitored after treatment.