Interstitial ablative techniques for hepatic tumours

Salvage 125I brachytherapy for liver metastases of colorectal cancer in anatomically challenging locations after failure of systemic chemotherapy-A retrospective study

PURPSOE

Colorectal cancer liver metastasis (CCLM) in anatomically challenging locations is difficult to treat. This retrospective study aimed to evaluate the effectiveness and safety of permanent ¹²⁵I seeds implantation (ISI) for treatment of CCLM in anatomically challenging locations after failure of systemic chemotherapy.

METHODS AND MATERIALS

A total of 31 liver metastases (in 25 patients) were treated by ISI under computerized tomography guidance from January 2011 to December 2017. Post-treatment follow-up was for 40 months. Adverse events were classified using the National Cancer Institute's Common Terminology Criteria for Adverse Events. Tumor response was evaluated by the mRECIST criteria. Objective response rate, overall survival rate, and complications were retrospectively analyzed.

RESULTS

All ISI procedures were performed successfully. Most patients only complained of fatigue and mild pain after ISI. Only one patient had liver rupture during the procedure. Serum alanine aminotransferase and aspartate aminotransferase levels at 1 month after ISI were not significantly different from pre-procedure levels (p > 0.05). Computed tomography at 6 months after ISI treatment showed completed response in 11 (11/31, 35.5%) lesions, partial response in 14 (14/31, 45.2%) lesions, stable disease in 4 (4/31, 12.9%) lesions, and disease progression in 2 (2/31, 6.5%) lesions; thus, the objective response rate was 80.6%. Median survival was for 12 months. The 1 and 2 year overall survival rates were 52.0% and 20.0%, respectively.

CONCLUSIONS

¹²⁵I seeds implantation for CCLM in anatomically challenging locations is safe and effective. Survival benefit is limited in the salvage setting where patients have high intrahepatic tumor load after failed systemic chemotherapy.

A prospective randomized trial comparing microwave and radiofrequency ablation for the treatment of liver metastases using a dual ablation system ─ The Mira study

Purpose

The aim of this study was to prospectively compare the therapy response and safety of microwave (MWA) and radiofrequency ablation (RFA) for the treatment of liver metastases using a dual ablation system.

Methods

Fifty patients with liver metastases (23 men, mean age: 62.8 ± 11.8 years) were randomly assigned to MWA or RFA for thermal ablation using a one generator dual ablation system. Magnetic resonance imaging (MRI) was acquired before treatment and 24 h post ablation. The morphologic responses to treatment regarding size, volume, necrotic areas, and diffusion characteristics were evaluated by MRI. Imaging follow-up was obtained for one year in three months intervals, whereas clinical follow-up was obtained for two years in all patients.

Results

Twenty-six patients received MWA and 24 patients received RFA (mean diameter: 1.6 cm, MWA: 1.7 cm, RFA: 1.5 cm). The mean volume 24 h after ablation was 37.0 cm³ (MWA: 50.5 cm³, RFA: 22.9 cm³, P < 0.01). The local recurrence rate was 0% (0/26) in the MWA-group and 8.3% (2/24) in the RFA-group (P = 0.09). The rate of newly developed malignant formations was 38.0% (19/50) for both groups (MWA: 38.4%, RFA: 37.5%, P = 0.07). The overall survival rate was 70.0% (35/50) after two years (MWA: 76.9%, RFA: 62.5%, P = 0.60). No major complications were reported.

Conclusion

In conclusion, MWA and RFA are both safe and effective methods for the treatment of liver metastases with MWA generating greater volumes of ablation. No significant differences were found for overall survival, rate of neoplasm, or major complications between both groups.

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A dual ablation system allows for MWA and RFA treatment using the same hardware.

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Both methods are safe and effective for the treatment of liver metastases.

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MWA generates greater volumes of ablation and larger ablative margins compared to RFA.

Missing colorectal liver metastases: the surgical challenge

BACKGROUND

New chemotherapy schemes have allowed for a better radiological response of unresectable colorectal liver metastases, leading to an interesting scenario known as a complete radiological response. The aim of this study was to review the current management of missing liver metastases (MLM) from the liver surgeon's point of view.

METHODS

A systematic search was conducted on all publications of PubMed and Embase between 2003 and 2018. Meta-analysis was performed on MLM resected/unresected. Residual tumor or regrowth and relapse-free survival were used as evaluation indices.

RESULTS

After literature search, 18 original articles were included for analysis. The predictive factors for MLM are type and duration of chemotherapy and size and number of lesions. Magnetic resonance is the most sensitive preoperative technique. Regarding clinical management, liver surgery is deemed the fundamental pillar in the therapeutic strategy of these patients. Meta-analysis due to data heterogeneity was inconclusive.

CONCLUSIONS

Depending on the clinical context, MLM monitoring appears to be a valid therapeutic alternative. Nevertheless, prospective randomized clinical studies are needed.

High-intensity focused ultrasound alone or combined with transcatheter arterial chemoembolization for the treatment of hepatocellular carcinoma with unsuitable indications for hepatectomy and radiofrequency ablation: a phase II clinical trial

OBJECTIVES

This study aims to evaluate the efficacy and safety of high-intensity focused ultrasound (HIFU) alone or combined with transcatheter arterial chemoembolization (TACE) for patients with hepatocellular carcinoma (HCC) but were contraindicated for hepatectomy and radiofrequency ablation (RFA).

METHODS

Patients between 20 and 80 years of age with 1-3 foci of HCC were selected. Included patients have had primary or recurrent liver lesions with no evidence of extra-hepatic metastasis prior to the study. Patients were treated with ultrasound-guided HIFU alone or HIFU combined with TACE (treated with TACE once within 4 weeks prior to receiving HIFU).

RESULTS

Thirty-seven patients were enrolled, for a total of 45 lesions. The 2-year local control (LC) rate was 73.0% and the median LC time was 22 months. The 2-year progression-free survival (PFS) was 29.7% and the median PFS time was 9 months. Finally, the 2-year overall survival (OS) was 70.3%, and the median OS time was 24 months. The most common adverse events (AEs) were elevated liver enzymes, followed by fatigue, and pain, no grade 4 AEs or death occurred. Multivariate analysis showed that age, Child-Pugh class, and the number of tumors were independent prognostic factors for PFS and that the AFP levels and the number of tumors were significantly correlated with the OS.

CONCLUSIONS

This study indicates that the HIFU/HIFU combined with TACE treatment is safe, and is capable of achieving both a good LC rate and a considerably good prognosis. The procedure should be considered for patients who were deemed unsuitable for other local treatments.

HIFU for the treatment of difficult colorectal liver metastases with unsuitable indications for resection and radiofrequency ablation: a phase I clinical trial

BACKGROUND

The goal of this study is to evaluate the safety and efficacy of high intensity focused ultrasound (HIFU) for patients with colorectal liver metastases (CRLM) but were contraindicated for resection and radiofrequency ablation.

METHODS

Patients between 20 and 80 years of age with 1-3 liver metastases from colorectal cancer were selected. Included patients have had their primary lesions removed with no evidence of extrahepatic metastasis prior to the study. Ultrasound-guided HIFU was employed and target regions' ablation was achieved with repeated sonications from the deep to shallow regions of the tumors section by section.

RESULTS

Thirteen patients were enrolled. The most common adverse events (AEs) were pain (n = 8), followed by fatigue (n = 7), increased aspartate aminotransferase (AST) (n = 7), increased alanine aminotransferase (ALT) (n = 5), and skin edema (n = 4). No grade ≥ 3 AEs occurred and while most patients (76.9%) achieved a complete response, three patients achieved a partial response. The objective response rate was 100% after the first HIFU treatment. Nine patients relapsed but the tumors were mostly isolated to the liver (8/9). The median follow-up period was 25 months. The 2-year progression-free survival (PFS) was 16.7%, and the median PFS was 9 months. Notably, the 2-year overall survival (OS) was 77.8%, and the median OS was 25 months.

CONCLUSION

This study indicates that the HIFU treatment is safe, is able to achieve a good tumor response rate and long-term prognosis even when the foci were in high-risk locations, and should be considered for patients who were considered unsuitable for other local treatments.

Intravesical device-assisted therapies for non-muscle-invasive bladder cancer

Non-muscle-invasive bladder cancer (NMIBC), the most prevalent type of bladder cancer, accounts for ~75% of bladder cancer diagnoses. This disease has a 50% risk of recurrence and 20% risk of progression within 5 years, despite the use of intravesical adjuvant treatments (such as BCG or mitomycin C) that are recommended by clinical guidelines. Intravesical device-assisted therapies, such as radiofrequency-induced thermochemotherapeutic effect (RITE), conductive hyperthermic chemotherapy, and electromotive drug administration (EMDA), have shown promising efficacy. These device-assisted treatments are an attractive alternative to BCG, as issues with supply have been a problem in some countries. RITE might be an effective treatment option for some patients who have experienced BCG failure and are not candidates for radical cystectomy. Data from trials using EMDA suggest that it is effective in high-risk disease but requires further validation, and results of randomized trials are eagerly awaited for conductive hyperthermic chemotherapy. Considerable heterogeneity in patient cohorts, treatment sessions, use of maintenance regimens, and single-arm study design makes it difficult to draw solid conclusions, although randomized controlled trials have been reported for RITE and EMDA.

Histotripsy for Non-Invasive Ablation of Hepatocellular Carcinoma (HCC) Tumor in a Subcutaneous Xenograft Murine Model

Histotripsy fractionates tissue through a mechanical, non-invasive ultrasonic ablation process that precisely controls acoustic cavitation while utilizing real-time ultrasound (US) imaging guidance. This study investigates the potential, feasibility and tumor volume reduction effects of histotripsy for liver cancer ablation in a subcutaneous in vivo murine Hepatocellular Carcinoma (HCC) model. Hep3B tumors were generated in the right flanks of 14 NSG and 7 NOD-SCID mice. The mice were grouped as follows: A (acute, NSG with n=9 treatment and n=1 control), B (chronic, NSG with n=2 treatment and n=2 control) and C (chronic NODSCID, with n=6 treatment and n=1 control). Treatment was performed when the tumor diameters reached >5 mm. 1-2 cycle histotripsy pulses at 100 Hz PRF (p- >30 MPa) were delivered using a custom built 1 MHz therapy transducer attached to a motorized positioner, which scanned the transducer focus to traverse the targeted tumor volume, guided by real-time US imaging. Tumor ablation effectiveness was assessed by obtaining T1, T2 and T2* weighted MR images. Post euthanasia, treated tumor, brain, and lung tissue samples were harvested for histology. Histology of acute group A showed fractionation of targeted region with a sharp boundary separating it from untreated tissue. Groups B and C demonstrated effective tumor volume reduction post treatment on MRI as the homogenate and edema were resorbed within 23 weeks. However, as the tumor was subcutaneous, it was not possible to set adequate treatment margin and since the mice were immune-compromised, residual viable tumor cells eventually developed into tumor regrowth at 3-9 weeks after histotripsy. Groups B and C showed no signs of metastasis in the lung and brain. Our study successfully demonstrated the potential of histotripsy for non-invasive HCC ablation in a subcutaneous murine model. Additional work is ongoing to study the response of histotripsy in immune-competent orthotopic liver tumor models.

Non-Invasive Liver Ablation Using Histotripsy: Preclinical Safety Study in an In Vivo Porcine Model

This study investigates the safety profile for use of histotripsy, a non-invasive ultrasonic ablation method currently being developed for the treatment of liver cancer, for liver ablation in an in vivo porcine model. Histotripsy treatments were applied to the liver and hepatic veins of 22 porcine subjects, with half of the subjects receiving systemic heparinization. Vital signs (heart rate, blood pressure, temperature, electrocardiogram and SpO₂) were monitored throughout the procedure and for 1 h post-treatment. Blood was drawn at six points during the experiment to analyze blood gases, liver function and free hemoglobin levels. All treatments were guided and monitored by real-time ultrasound imaging. After treatment, the tissue was harvested for histological analysis. Results indicated that histotripsy generated well-defined lesions inside the liver and around the treated hepatic veins of all subjects in both treatment groups. Vital signs and blood analysis revealed that animals responded well to histotripsy, with all animals surviving the treatment. One animal in the non-heparinized group had a transient increase in pH and decreases in blood pressure, heart rate and PCO₂ during the 15-min vessel treatment, with these changes returning to baseline levels soon after the treatment. Overall, the results indicate that histotripsy can safely be performed on the liver without the need for systemic heparinization, even in regions containing large hepatic vessels, supporting its future use for the treatment of liver cancer.

Non-Invasive Ultrasound Liver Ablation Using Histotripsy: Chronic Study in an In Vivo Rodent Model

Hepatocellular carcinoma, or liver cancer, has the fastest growing incidence among cancers in the United States. Current liver ablation methods are thermal-based and share limitations due to the heat sink effect from the blood flow through the highly vascular liver. Recently, our group has investigated histotripsy as a non-invasive liver cancer ablation method. Histotripsy is a non-thermal ultrasonic ablation method that fractionates tissue through the control of acoustic cavitation. Previous experiments in an in vivo porcine model show that histotripsy can create well-confined lesions in the liver through ribcage obstruction without damaging the overlying ribs and other tissues. Histotripsy can also completely fractionate liver tissue surrounding major vessels while preserving the vessels. In this study, we investigate the long-term effects of histotripsy liver ablation in a rodent model. We hypothesize that the fractionated histotripsy lesion will be resorbed by the liver, resulting in effective tissue healing. To test this hypothesis, the livers of 20 healthy rats were treated with histotripsy using an 8-element 1-MHz histotripsy transducer. Rats were euthanized after 0, 3, 7, 14 and 28 days (n = 4). In vivo and post mortem results showed histotripsy lesions were successfully generated through the intact abdomen in all 20 rats. Magnetic resonance imaging found primarily negative contrast on day 0, positive contrast on day 3 and rapid normalization of signal intensity thereafter (i.e., signal amplitude returned to baseline levels seen in healthy liver tissue). Histologically, lesions were completely fractionated into an acellular homogenate. The lesions had a maximum cross-sectional area of 17.2 ± 1.9 mm(2) and sharp boundaries between the lesion and the healthy surrounding tissue after treatment. As the animals recovered after treatment, the histotripsy tissue homogenate was almost completely replaced by regenerated liver parenchyma, resulting in a small fibrous lesion (<1 mm(2) maximum cross-section) remaining after 28 d. The results of this study suggest that histotripsy has potential as a non-invasive liver ablation method for effective tissue removal.

Surgery for colorectal liver metastases

Half of all patients with colorectal cancer develop metastatic disease. The liver is the principal site for metastases, and surgical resection is the only modality that offers the potential for long-term cure. Appropriate patient selection for surgery and improvements in perioperative care have resulted in low morbidity and mortality rates, resulting in this being the therapy of choice for suitable patients. Modern management of colorectal liver metastases is multimodal incorporating open and laparoscopic surgery, ablative therapies such as radiofrequency ablation or microwave ablation and (neo)adjuvant chemotherapy. The majority of patients with hepatic metastases should be considered for resectional surgery, if all disease can be resected, as this offers the only opportunity for prolonged survival.

Fatal arterial hemorrhage after microwave ablation of multiple liver metastases: The lessons learned

We report the case of a 71-year-old female patient with previous history of rectal cancer. The primary cancer was resected and three cycles of chemotherapy were completed. Excision of metastatic lesions was also performed from the left liver lobe. Due to the presence of new liver lesions on the right lobe, intra-operative microwave ablation was decided. Three hours post ablation the patient bled massively and angiography revealed extravasation from a peripheral branch of the right hepatic artery. Successful embolization was performed; however, the patient died 5 days later on liver failure. We would like to present the case and discuss the technical options and the key points to help avoiding similar complications in the future.

Image-guided non-invasive ultrasound liver ablation using histotripsy: feasibility study in an in vivo porcine model

Hepatocellular carcinoma (HCC), or liver cancer, is one of the fastest growing cancers in the United States. Current liver ablation methods are thermal based and share limitations resulting from the heat sink effect of blood flow through the highly vascular liver. In this study, we explore the feasibility of using histotripsy for non-invasive liver ablation in the treatment of liver cancer. Histotripsy is a non-thermal ablation method that fractionates soft tissue through the control of acoustic cavitation. Twelve histotripsy lesions ∼1 cm(3) were created in the livers of six pigs through an intact abdomen and chest in vivo. Histotripsy pulses of 10 cycles, 500-Hz pulse repetition frequency (PRF), and 14- to 17-MPa estimated in situ peak negative pressure were applied to the liver using a 1-MHz therapy transducer. Treatments were performed through 4-6 cm of overlying tissue, with 30%-50% of the ultrasound pathway covered by the rib cage. Complete fractionation of liver parenchyma was observed, with sharp boundaries after 16.7-min treatments. In addition, two larger volumes of 18 and 60 cm(3) were generated within 60 min in two additional pigs. As major vessels and gallbladder have higher mechanical strength and are more resistant to histotripsy, these remained intact while the liver surrounding these structures was completely fractionated. This work shows that histotripsy is capable of non-invasively fractionating liver tissue while preserving critical anatomic structures within the liver. Results suggest histotripsy has potential for the non-invasive ablation of liver tumors.

Radiofrequency ablation in the treatment of liver metastases from colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the most common malignant tumour and the third leading cause of cancer deaths in USA. For advanced CRC, the liver is the first site of metastatic disease; approximately 50 % of patients with CRC will develop liver metastases either synchronously or metachronously within 2 years after primary diagnosis. Hepatic resection (HR) is the only curative option, but only 15-20% of patients with liver metastases from CRC (CRLMs) are suitable for surgical standard treatment. In patients with unresectable CRLMs downsizing chemotherapy can improve resectability (16%). Modern systemic chemotherapy represents the only significant treatment for unresectable CRLMs. However several loco-regional treatments have been developed: hepatic arterial infusion (HAI), cryosurgical ablation (CSA), radiofrequency ablation (RFA), microwave ablation and selective internal radion treatment (SIRT). During the past decade RFA has superseded other ablative therapies, due to its low morbidity, mortality, safety and patient acceptability.

OBJECTIVES

The objective of this study was to systematically review the role of radiofrequency ablation (RFA) in the treatment of CRLMs.

SEARCH METHODS

We performed electronic searches in the following databases:CENTRAL, MEDLINE and EMBASE. Current trials were identified through the Internet using the Clinical-Trials.gov site (to January 2, 2012) and ASCO Proceedings. The reference lists of identified trials were reviewed for additional studies.

SELECTION CRITERIA

Randomized clinical trials (RCTs), quasi-randomised or controlled clinical trials (CCTs) comparing RFA to any other therapy for CRLMs were included. Observational study designs including comparative cohort studies comparing RFA to another intervention, single arm cohort studies or case control studies have been included if they have: prospectively collected data, ten or more patients; and have a mean or median follow-up time of 24 months. Patients with CRLMs who have no contraindications for RFA. Patients with unresectable extra-hepatic disease were also included.Trials have been considered regardless of language of origin.

DATA COLLECTION AND ANALYSIS

A total of 1144 records were identified through the above electronic searching. We included 18 studies: 10 observational studies, 7 Clinical Controlled Trials (CCTs) and an additional 1 Randomized Clinical Trial (RCT) (abstract) identified by hand searching in the 2010 ASCO Annual Meeting. The most appropriate way of summarizing time-to-event data is to use methods of survival analysis and express the intervention effect as a hazard ratio. In the included studies these outcome are mostly reported as dichotomous data so we should have asked authors research data for each participant and perform Individual Patient Data (IPD) meta-analysis. Given the study design and low quality of included studies we decided to give up and not to summarize these data.

MAIN RESULTS

Seventeen studies were not randomised and this increases the potential for selection bias. In addition, there was imbalance in the baseline characteristics of the participants included in all studies. All studies were classified as having a elevate risk of bias. The assessment of methodological quality of all non-randomized studies included in meta-analysis performed by the STROBE checklist has allowed us to identify several methodological limits in most of the analysed studies. At present, the information from the single RCT included (Ruers 2010) comes from an abstract of 2010 ASCO Annual Meeting where the allocation concealment was not reported; however in original protocol allocation concealment was adequately reported (EORTC 40004 protocol). The heterogeneity regarding interventions, comparisons and outcomes rendered the data not suitable.

AUTHORS' CONCLUSIONS

This systematic review gathers information from several controlled clinical trials and observational studies which are vulnerable to different types of bias. The imbalance between characteristics of patients in the allocated groups appears to be the main concern. Only one randomised clinical trial (published as an abstract), comparing 60 patients receiving RFA plus CT versus 59 patients receiving CT alone, was identified. This study showed that PFS was significantly higher in the group that received RFA. However, it was not able to provide information on overall survival. In conclusion, evidence from the included studies are insufficient to recommend RFA for a radical oncological treatment of CRLMs.

Thermal ablation and high-temperature thermal therapy: Overview of technology and clinical implementation

High-temperature hyperthermia or thermal therapy is being applied for destruction of cancerous tissue, eradication or reduction of benign tumours and targeted tissue modification and remodelling. Many of these high-temperature technologies provide a minimally-invasive alternative with lower morbidities compared to the traditional surgical procedures. The effects of high-temperature thermal exposure on tissues, examples of heating technology and procedures of clinical practice related to high-temperature thermal therapy are reviewed. This brief review encompasses interstitial, endocavity, intraluminal and external applications of RF, microwave, ultrasound, laser and thermal conduction energy sources. The technology is prevalent and in various levels of advancement, with the move toward more spatially-accurate and controllable heating systems combined with image-guidance and treatment verification warranted, especially for the treatment of cancer.

Changes in interleukin-1β and 6 after hepatic microwave tissue ablation compared with radiofrequency, cryotherapy and surgical resections

BACKGROUND

Cytokine changes after microwave tissue ablation (MTA) were compared with hepatic resection, cryotherapy (CRYO), and radiofrequency ablation (RFA). Cytokine production was measured at various ablation volumes for each modality and correlated with the transitional inflammatory zone produced by the ablation techniques.

METHODS

Live rats underwent MTA, surgical resection, CRYO or RFA of 15%, 33%, or 66% of the total hepatic volume. Serum samples were collected preoperatively and at 1, 3, 6, 24, and 48 hours after surgery and analyzed for pro-inflammatory cytokines interleukin (IL)-1β and IL-6.

RESULTS

Significantly higher levels of both cytokines were present after CRYO and RFA compared with MTA, hepatic resection, or controls (P < .001). All animals survived except those undergoing RFA or CRYO of 66% of the hepatic volume, which died within 6 hours. Transitional zones produced after RFA were larger than those after CRYO or MTA, but no correlation was present with the amount of cytokines.

CONCLUSIONS

Large-volume MTA is associated with a significant decreased cytokine response and is well tolerated compared with RFA and CRYO.

Comparison of gadoxetic acid-enhanced MR imaging versus four-phase multi-detector row computed tomography in assessing tumor regression after radiofrequency ablation in subjects with hepatocellular carcinomas

PURPOSE

To assess the diagnostic value of gadoxetic acid-enhanced magnetic resonance (MR) imaging in follow-up of patients with hepatocellular carcinomas (HCCs) who were treated with radiofrequency (RF) ablation and to compare it with that of four-phase multi-detector row computed tomography (CT).

MATERIALS AND METHODS

From July 2007 to May 2008, 36 patients (43 HCCs) were enrolled who were treated with RF ablation (tumor size, 20-47 mm; mean, 24.5 mm) and underwent gadoxetic acid-enhanced MR imaging and four-phase (precontrast, arterial, portal venous, and equilibrium) multidetector CT for follow-up. Two radiologists independently reviewed these images, and conspicuity of tumor margins and detection of residual or recurrent tumor were assessed on a five-point scale with receiver operating characteristic (ROC) curve analysis. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were evaluated.

RESULTS

The mean conspicuity value of tumor margins was significantly higher on MR imaging than on multidetector CT (P < .001). The degree of differentiation between residual/recurrent tumor and hyperemia was significantly greater on MR imaging (P < .001). The mean area under the ROC curve was significantly higher with MR imaging (P = .015), as were sensitivity, specificity, PPV, NPV, and accuracy of detection rate (mean, 100%, 96.2%, 82.4%, 100%, and 96.7%, respectively, vs 41.7%, 56.8%, 13.5%, 85.7%, and 54.7% for multidetector CT). The interobserver agreement rate for MR imaging was higher (0.919) than for multidetector CT (0.672; P < .05).

CONCLUSIONS

Diagnostic accuracy, conspicuity of tumor margins, and detection rate of residual or recurrent tumor were found to be better with gadoxetic acid-enhanced MR imaging than with four-phase multidetector CT.

915MHz microwave ablation with implanted internal cooled-shaft antenna: initial experimental study in in vivo porcine livers

PURPOSE

To explore a preferred power output for further clinical application based on the ablated lesions induced by the four power outputs of 915 MHz microwave in experimental study of in vivo porcine livers.

MATERIALS AND METHODS

A KY 2000-915 microwave ablation system with an implanted 915 MHz internal cooled-shaft antenna was used in this study. A total of 24 ablations were performed in eight in vivo porcine livers. The energy was applied for 10 min at microwave output powers of 50 W, 60 W, 70 W, and 80 W. Long-axis and short-axis diameters of the coagulation zone were measured on all gross specimens.

RESULTS

The shapes of the 915 MHz microwave ablation lesions were elliptical commonly. As the power increased, the long-axis and short-axis diameters of the coagulation zone had a tendency to rise. But the long-axis diameter of the ablated lesion at 50 W was not significantly smaller than that of the ablated lesion at 60 W (P>0.05) and there were no statistical differences in short-axis diameters of the ablated lesion among the three power outputs of 60 W, 70 W and 80 W (P>0.05). After 10 min irradiation of 60 W, the long-axis and short-axis diameters of the coagulation zone were 5.02±0.60 cm and 3.65±0.46 cm, respectively.

CONCLUSIONS

For decreasing the undesired damages of liver tissues along the shaft and the number of antenna in further clinically percutaneous microwave ablation treatment, the power of 60 W may be a preferred setting among the four power outputs used in present study.

A family of new instruments for laparoscopic radiofrequency ablation of malignant liver lesions

Primary and secondary liver tumors may be treated with radiofrequency ablation (RFA) to improve tumor control and to increase patient survival. Lesions are punctured percutaneously or during open surgery. However, not all of the lesions are accessible percutaneously due to their localization: Adjacent structures could be endangered and/or the treatment would cause severe pain. Open surgery is an option in these cases but significantly more invasive. Laparoscopic RFA (LRFA) is an additional possibility in those cases: It offers a better access to difficult lesions than via the percutaneous route and is also less invasive than open surgery. The precision of targeting, however, in LRFA still has to be improved. In an in-vivo feasibility study we used a tumor mimic model in pigs to examine the applicability of laparoscopic RFA in combination with laparoscopic ultrasound using a set of dedicated new instruments to handle the RFA probe. To increase the ablation volume, the liver blood flow was reduced performing a Pringle maneuver. It is demonstrated that this set of specially designed instruments is indeed applicable and facilitates the targeting of liver lesions of any localization. Accordingly, it could significantly enlarge the applicability of LRFA.

Meta-analysis of percutaneous radiofrequency ablation versus ethanol injection in hepatocellular carcinoma

BACKGROUND

Percutaneous radiofrequency ablation (RFA) has gained popularity in the treatment of hepatocellular carcinoma (HCC). However, its role versus other conventional minimally invasive therapies is still a matter of debate. The purpose of this work is to analyse the efficacy and safety of RFA versus that of ethanol injection (PEI), the percutaneous standard approach to treat nonsurgical HCC.

METHODS

Systematic review and meta-analysis of randomised or quasi-randomised controlled trials published up to August 2008 in PubMed, ISI Web of Science and The Cochrane Library. Overall survival, local recurrence rate and adverse effects were considered as primary outcomes. Studies were critically appraised and estimates of effect were calculated according to the random-effects model. Inconsistency across studies was evaluated using the I2 statistic. Sensitivity analyses were conducted to explore statistical heterogeneity.

RESULTS

Six studies were eligible. The studies reported data on 396 patients treated by RFA and 391 treated by PEI. In general, subjects were in Child-Pugh class A (74%) and had unresectable HCC (mean size 2.5 cm). Mean follow-up was 25 +/- 11 months. The survival rate showed a significant benefit for RFA over PEI at one, two, three and four years. The advantage in survival increased with time with Relative Risk values of: 1.28 (95%CI:1.12-1.45) and 1.24 (95%CI:1.05-1.48) for RFA versus PEI at 3- and 4-years respectively. Likewise, RFA achieved significantly lower rates of local recurrence (RR: 0.37, 95%CI: 0.23-0.59). The overall rate of adverse events was higher with RFA (RR:2.55, 95%CI: 1.8-3.6) yet no significant differences were found concerning major complications (RR:1.85, 95%CI: 0.68-5.01). There was not enough evidence supporting a better cost-effectiveness ratio for RFA compared to PEI.

CONCLUSION

Available evidence from adequate quality controlled studies support the superiority of RFA versus PEI, in terms of better survival and local control of the disease, for the treatment of patients with relatively preserved liver function and early-stage non-surgical HCC. However, the higher rate of adverse events displayed is something that will have to be tested with appropriate weighting of the possible benefits in each individual case. Overall cost-effectiveness of RFA needs further evaluation.

Ultrasound monitoring of in vitro radio frequency ablation by echo decorrelation imaging

OBJECTIVE

The purpose of this study was to test ultrasound echo decorrelation imaging for mapping and characterization of tissue effects caused by radio frequency ablation (RFA).

METHODS

Radio frequency ablation procedures (6-minute duration, 20-W power) were performed on fresh ex vivo bovine liver tissue (n = 9) with continuous acquisition of beam-formed ultrasound echo data from a 7-MHz linear array. Echo data were processed to form B-scan images, echo decorrelation images (related to rapid random changes in echo waveforms), and integrated backscatter images (related to local changes in received echo energy). Echo decorrelation and integrated backscatter values at the location of a low-noise thermocouple were assessed as functions of temperature. Echo decorrelation and integrated backscatter images were directly compared with ablated tissue cross sections and quantitatively evaluated as predictors of tissue ablation and overtreatment.

RESULTS

Echo decorrelation maps corresponded with local tissue temperature and ablation effects. Consistent echo decorrelation increases were observed for temperatures above 75 degrees C, whereas integrated backscatter maps showed a nonmonotonic temperature dependence complicated by acoustic shadowing, with high variance at large temperature elevations. In receiver operating characteristic curve analysis of echo decorrelation and integrated backscatter maps as predictors of local tissue ablation, echo decorrelation performed well (area under the receiver operating characteristic curve [AUROC] = 0.855 for ablation and 0.913 for overtreatment), whereas integrated backscatter performed poorly (AUROC < 0.6).

CONCLUSIONS

Echo decorrelation imaging can map tissue changes due to RFA in vitro, with local echo decorrelation corresponding strongly to local tissue temperature elevations and ablation effects. With further development and in vivo validation, echo decorrelation imaging is potentially useful for improved image guidance of clinical RFA procedures.

Radiofrequency ablation of liver tumors: a novel needle perfusion technique enhances efficiency

OBJECTIVE

We hypothesize that perfusion of an expandable radiofrequency ablation (RFA) needle with saline solution might help prevent charring and increase efficiency.

SUMMARY BACKGROUND DATA

RFA has become an important adjunct to modern liver surgery. However, ablation is time-consuming and hazardous due to charring around the radiofrequency electrodes.

METHODS

From June 2000 to November 2004, 159 liver tumors with a median diameter of 2.0 cm were treated with RFA, 54 tumors of them according to the manufacturer's standard protocol and 105 tumors according to the novel perfusion protocol. No randomization was applied. All patients were followed up with contrast enhanced computed tomography (CT) at regular intervals. Local recurrence was defined as radiologic and/or histologic evidence of viable tumor within or at the ablated liver area.

RESULTS

Both study groups were comparable with regard to tumor characteristics, procedure related complications, and median times of follow-up (27 mo in the standard group versus 23 mo in the perfusion group). The median RFA time was significantly reduced from 18.9 min in the standard group to 8.0 min in the perfusion group. The rates of incomplete ablations were comparable in both groups (3.7% versus 2.8%). The rate of local recurrences at the RFA site was 6.9% overall, 11.1% in the standard group, and 4.8% in the perfusion group. No tumor seeding along the puncture channel was observed.

CONCLUSIONS

The perfusion of an expandable RFA needle with saline solution significantly accelerates the ablation procedure of liver tumors without increase of complications and without compromising the oncosurgical result.

Cryosurgical ablation of hepatic colorectal metastases

Hepatic resection is the treatment of choice for primary and secondary hepatic tumors but only 15-25% of patients with hepatic colorectal metastases are eligible for a curative hepatic resection. Cryosurgical ablation (CSA) is employed when curative resection of metastases cannot be obtained. Sixty-four patients (35 males, 29 females, mean age 58.8 years, range 30-79 years) with hepatic colorectal metastases underwent CSA, under laparoscopic control (15 cases) or with open surgery (49 cases), with subsequent close follow-up. Intraoperative bleeding occurred in 32 out of 49 patients in the open group and only in 2 patients in the laparoscopic group. Minor morbidity that resolved with conservative treatment was 54.8% in the open group and 53.3% in the laparoscopic group. Major morbidity occurred in 11 cases (26.2%) in the open group and in 1 case (6.7%) in the laparoscopic group. Mortality occurred in two patients, both in the open group, from renal insufficiency in one case and from liver failure in the other case. Mean hospital stay was 16.7 days in the open group (range 8-72 days) and 10.6 days in the laparoscopic group (range 3-18 days). No patient was lost to follow-up. At a mean follow-up of 87.1 months (range 52.2-125.2 months), selected patients undergoing laparoscopic CSA had an overall survival rate of 66.7% (10 patients), with 30% of patients (3) who are disease-free. Median survival was 94.2 months. Recurrence was observed in seven patients. None of the intrahepatic recurrences was at the cryoablation site. In the open group, median survival was 22.9 months with a survival rate of 30.9% (13 patients) at a mean follow-up of 39.3 months (range 1.9-124.5 months); 9 patients (19.1%) are disease-free. In selected patients, laparoscopic CSA is associated with survival rates which are similar to those after hepatic resection. In patients with a larger tumor burden, CSA offers a curative treatment to patients with otherwise a dismal prognosis and it improves survival as compared to patients receiving chemotherapy alone. However, the procedure is associated with substantial morbidity, particularly bleeding, and therefore careful patient selection is recommended.

Telefones celulares: influência nos sistemas auditivo e vestibular

Os sistemas de telecomunicações emitem radiofreqüência, uma radiação eletromagnética invisível. Telefones celulares transmitem microondas (450900 MHz no sistema analógico e 1,82,2 GHz no sistema digital), muito próximo à orelha do usuário. Esta energia é absorvida pela pele, orelha interna, nervo vestibulococlear e superfície do lobo temporal. OBJETIVO: Revisar a literatura sobre influência dos telefones celulares na audição e equilíbrio. FORMA DE ESTUDO: Revisão sistemática. METODOLOGIA: Foram pesquisados artigos nas bases Lilacs e Medline sobre a influência dos telefones celulares nos sistemas auditivo e vestibular, publicados de 2000 a 2005, e também materiais veiculados na Internet. RESULTADOS: Os estudos sobre radiação do telefone celular e risco de neurinoma do acústico apresentam resultados contraditórios. Alguns autores não encontram maior probabilidade de aparecimento do tumor nos usuários de celulares, enquanto outros relatam que a utilização de telefones analógicos por 10 anos ou mais aumenta o risco para o tumor. A exposição aguda às microondas emitidas pelo celular não influencia a atividade das células ciliadas externas da cóclea, in vivo e in vitro, a condução elétrica no nervo coclear, nem a fisiologia do sistema vestibular em humanos. As próteses auditivas analógicas são mais suscetíveis à interferência eletromagnética dos telefones celulares digitais. CONCLUSÃO: Não há comprovação de lesão cocleovestibular pelos telefones celulares.

Mobile phones: influence on auditory and vestibular systems

Telecommunications systems emit radiofrequency, which is an invisible electromagnetic radiation. Mobile phones operate with microwaves (450900 MHz in the analog service, and 1,82,2 GHz in the digital service) very close to the user's ear. The skin, inner ear, cochlear nerve and the temporal lobe surface absorb the radiofrequency energy.

Aim

literature review on the influence of cellular phones on hearing and balance.

Study design

systematic review.

Methods

We reviewed papers on the influence of mobile phones on auditory and vestibular systems from Lilacs and Medline databases, published from 2000 to 2005, and also materials available in the Internet.

Results

Studies concerning mobile phone radiation and risk of developing an acoustic neuroma have controversial results. Some authors did not see evidences of a higher risk of tumor development in mobile phone users, while others report that usage of analog cellular phones for ten or more years increase the risk of developing the tumor. Acute exposure to mobile phone microwaves do not influence the cochlear outer hair cells function in vivo and in vitro, the cochlear nerve electrical properties nor the vestibular system physiology in humans. Analog hearing aids are more susceptible to the electromagnetic interference caused by digital mobile phones.

Conclusion

there is no evidence of cochleo-vestibular lesion caused by cellular phones

Serum cytokine levels in response to hepatic cryoablation

BACKGROUND AND OBJECTIVES

Cryogenic treatment sometimes stimulates the immune system by releasing intracellular antigens. We evaluated anti-tumor immune response by analyzing alterations in serum cytokine levels.

METHODS

Percutaneous cryosurgery was performed in 13 patients with unresectable tumors. Serum levels of interleukin (IL) -4, -6, and -10, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma were measured by enzyme-linked immunosorbent assay (ELISA). The Th1/Th2 ratio was estimated from the IFN-gamma/IL-4 ratio.

RESULTS

Levels of serum factors in the immune reaction (IR) group, in which tumor necrosis was identified not only in the treated area but also away from the treated area, were compared with those in the local effect (LE) group. Serum amyloid A (SAA), C-reactive protein (CRP), and IL-6 levels were increased in both groups after three treatments. The serum IL-10 level tended to increase with the number of treatments. Pretreatment IL-10 levels in the LE group were significantly greater than those in the IR group, and the maximum value in the LE group (59.5 +/- 13.2 pg/ml) was greater than that in the IR group (47.0 +/- 15.0 pg/ml). The TNF-alpha level was increased in the IR group. Pretreatment TNF-alpha levels and maximum levels in response to treatment were significantly greater in the IR group than in the LE group (P = 0.0313). The Th1/Th2 ratio was increased in the IR group, and the maximum ratio was significantly greater in the IR group than in the LE group.

CONCLUSION

It might be possible to evaluate the appearance of immune responses to cryosurgery by monitoring serum cytokine levels.

Proof of concept percutaneous treatment system to enable fast and finely controlled ablation of biological tissue

A prototype system has been developed for producing controllable ablation of spherical lesions with a diameter of up to 2 cm. The system is based on a solid-state energy source operating in the super high frequency (SHF is defined as being a frequency of between 3 and 30 GHz) region of the electromagnetic spectrum. Results obtained from preliminary tissue testing, performed on morbid tissue samples prepared in a laboratory environment, show repeatability in terms of shape and size of ablation, and demonstrate the ability to produce controlled ablation in morbid liver and kidney models.

Differences in ablation size in porcine kidney, liver, and lung after cryoablation using the same ablation protocol

OBJECTIVE

The purpose of our study was to assess the variation in size of acute necrosis and the variation in thermal map measured during cryoablation in multiple organs using the same ablation protocol for each organ.

MATERIAL AND METHODS

Eight female pigs underwent one cryoablation per organ of kidney, lung, and liver performed with open surgery with a 2.4-mm cryoprobe. A 12- and 8-minute double-freeze cycle was used. Intratissue temperatures were monitored using 16-gauge thermometers spaced at 5.0-mm increments from the cryoprobe. The comparison of results among tissues was performed using the multiple analysis of variance. The -20 degrees C thermal diameter was correlated with tissue damage. The kidneys, lungs, and liver were removed and examined histologically for a pathologic complete coagulative necrosis zone.

RESULT

A single 2.4-mm cryoprobe had a mean ice ball diameter in kidney, lung, and liver of 38.5 +/- 4.7, 35.5 +/- 3.6, and 32.5 +/- 2.7 mm, respectively. A mean -20 degrees C thermal diameter was achieved at 24.07 +/- 1.38 mm in kidney, 12.76 +/- 3.0 mm in lung, and 8.8 +/- 3.7 mm in liver by means of regression analysis. The acute pathologic complete coagulative necrosis zone size was 21.0 +/- 1.56 mm (kidney), 11.6 +/- 1.48 mm (lung), and 8.0 +/- 1.20 mm (liver).

CONCLUSION

The inherent characteristics of different organs manifest different ablation zone sizes during cryoablation despite the same ablation protocol being used. This information should be factored into planning for ablation procedures.

Measurement and analysis of tissue temperature during microwave liver ablation

We measured tissue temperature changes during ex vivo microwave ablation (MWA) procedures for bovine liver tissue. Tissue temperature increased rapidly at the beginning of the MW power application. It came to a plateau at 100 degrees C to 104 degrees C before it increased again. We split the changes of tissue temperature versus time into four phases. This suggests that tissue temperature changes may be directly related to tissue water related phenomena during MWA, including evaporation, diffusion, condensation and tissue water composition. An additional analysis indicated the lesion boundary at approximately 50 degres C to 60 degrees C temperature. We also measured the water content of ablated tissue lesions and examined the relationship of tissue water content and tissue temperature by mapping temperature to remaining tissue water after ablation. The results demonstrate significant tissue water content changes and lead to a better understanding of tissue water movement.

A Phase II safety and effect on time to tumor progression study of intratumoral light infusion technology using talaporfin sodium in patients with metastatic colorectal cancer

BACKGROUND AND OBJECTIVES

Twenty-seven patients with refractory liver metastases from colorectal cancer took part in a Phase II study of the light infusion technology (Litx) light-activated drug/device system to assess safety and evaluate time to tumor progression (TTP).

METHODS

Litx consists of the light-activated drug, talaporfin sodium (LS11), activated intratumorally by a catheter-like array of light-emitting diodes (LEDs). After placement of the array via ultrasound or computed tomography (CT) guidance, LS11 was administered intravenously, followed 15-60 min later by light infusion for 2.8 hr. Patients were assessed for adverse events and tumor response using physical examination, laboratory values, and CT scan evaluation over a period of 60 days.

RESULTS

The observed occurrence of Litx treatment-related adverse events was minimal and cumulative toxicity did not occur when combined with chemotherapy. Assessment of TTP and tumor response rate, although statistically non-robust, suggest potential improvement.

CONCLUSIONS

The Litx system was shown to be safe for treating liver metastases from colorectal cancer and there was no cumulative toxicity when combined with standard systemic therapy. Preliminary assessments of TTP and tumor response rate justify further evaluation in a Phase III follow-up study.

Radiofrequency ablation permits an effective treatment for colorectal liver metastasis

BACKGROUND

Radiofrequency ablation (RFA) has become an important adjunct to modern liver surgery. However, scant knowledge on long-term outcome of RFA for colorectal liver metastasis is available, nowadays.

METHODS

This is a prospective clinical study of patients with liver metastasis of colorectal cancer who were treated by RFA between April 1, 1998, and November 30, 2004. Forty-seven patients with 147 liver metastases were treated with RFA in a total of 70 interventions. A metastasis resection was not feasible in 80% of the interventions. All the patients were followed up at regular intervals with contrast-enhanced computed tomography (CT) and laboratory tests including carcinoembryonic antigen (CEA).

RESULTS

No RFA-related mortality occurred. The median follow-up time after the diagnosis of liver metastasis was 33 months. The RFA-related morbidity was 7%. After the RFA, the expected median overall survival rate is, to date, 39 months. Overall survival rates at 1, 2 and 3 years were 88%, 80% and 57%, respectively. Local recurrence rates reached 8.8% overall and 1.6% for metastasis smaller than 3cm in diameter. No local recurrence occurred for metastasis smaller than 3cm in diameter if treated with the newest RFA device.

CONCLUSIONS

Excellent local tumour control was achieved with radiofrequency ablation of small liver metastasis. The expected overall survival rate of patients with RFA for unresectable or non-resected colorectal liver metastasis improved in comparison with the survival rate reported following the natural course (best supportive care) or chemotherapy. The low local recurrence rate of metastases of less than 3cm challenges the results obtained by the more invasive treatment of conventional liver surgery.

Synergy between in situ cryoablation and TLR9 stimulation results in a highly effective in vivo dendritic cell vaccine

Dendritic cells (DC) are professional antigen-presenting cells that play a pivotal role in the induction of immunity. Ex vivo-generated, tumor antigen-loaded mature DC are currently exploited as cancer vaccines in clinical studies. However, antigen loading and maturation of DC directly in vivo would greatly facilitate the application of DC-based vaccines. We have previously shown that in situ tumor destruction by ablative treatments efficiently delivers antigens for the in vivo induction of antitumor immunity. In this article, we show that although 20% of the draining lymph node DCs acquire intratumorally injected model antigens after in situ cryoablation, only partial protection against a subsequent tumor rechallenge is observed. However, we also show that a combination treatment of cryoablation plus TLR9 stimulation via CpG-oligodeoxynucleotides is far more effective in the eradication of local and systemic tumors than either treatment modality alone. Analysis of the underlying mechanism revealed that in situ tumor ablation synergizes with TLR9 stimulation to induce DC maturation and efficient cross-presentation in tumor-bearing mice, leading to superior DC function in vivo. Therefore, in situ tumor destruction in combination with CpG-oligodeoxynucleotide administration creates a unique "in situ DC vaccine" that is readily applicable in the clinic.

Efficient loading of dendritic cells following cryo and radiofrequency ablation in combination with immune modulation induces anti-tumour immunity

Dendritic cells (DC) are professional antigen-presenting cells that play a pivotal role in the induction of immunity. Ex vivo-generated, tumour antigen-loaded mature DC are currently exploited as cancer vaccines in clinical studies. However, antigen loading and maturation of DC directly in vivo would greatly facilitate the application of DC-based vaccines. We formerly showed in murine models that radiofrequency-mediated tumour destruction can provide an antigen source for the in vivo induction of anti-tumour immunity, and we explored the role of DC herein. In this paper we evaluate radiofrequency and cryo ablation for their ability to provide an antigen source for DC and compare this with an ex vivo-loaded DC vaccine. The data obtained with model antigens demonstrate that upon tumour destruction by radiofrequency ablation, up to 7% of the total draining lymph node (LN) DC contained antigen, whereas only few DC from the conventional vaccine reached the LN. Interestingly, following cryo ablation the amount of antigen-loaded DC is almost doubled. Analysis of surface markers revealed that both destruction methods were able to induce DC maturation. Finally, we show that in situ tumour ablation can be efficiently combined with immune modulation by anti-CTLA-4 antibodies or regulatory T-cell depletion. These combination treatments protected mice from the outgrowth of tumour challenges, and led to in vivo enhancement of tumour-specific T-cell numbers, which produced more IFN-γ upon activation. Therefore, in situ tumour destruction in combination with immune modulation creates a unique, ‘in situ DC-vaccine’ that is readily applicable in the clinic without prior knowledge of tumour antigens.

Transpleurodiaphragmatic cryosurgical ablation for recurrent unresectable colorectal liver metastases

BACKGROUND AND OBJECTIVES

Cryosurgical ablation (CSA) allows the focal destruction of unresectable liver metastases after previous liver resection. The abdominal approach may be difficult for recurrent colorectal cancer metastases located in the upper part of the remaining liver, close to the inferior vena cava (IVC), the hepatic veins, and the diaphragm. A transpleurodiaphragmatic access was assessed for safety and efficacy.

METHODS

Between September 1999 and July 2004, 13 patients with recurrent unresectable colorectal liver metastases underwent transpleurodiaphragmatic CSA via limited right thoracotomy. Seventeen lesions were treated; median diameter was 31 mm (range 13-40 mm). One to three cryoprobes were used, depending on the size and location of metastases.

RESULTS

There was no operative death; three patients developed minor complications (23%). Median hospital stay was 10 days (8-14 days). After a median follow-up of 26 months (range 8-69 months), 9 patients were alive, and 5 were disease-free. Six patients had liver recurrences outside the cryolesion. Median disease free survival was 12 months with 60% 3-year survival after CSA and 58% 5-year survival after first liver surgery.

CONCLUSIONS

Transpleurodiaphragmatic CSA is safe and effective in selected patients with unresectable recurrent liver metastases from colorectal cancer.

Magnetic resonance imaging findings after laparoscopic renal cryoablation

OBJECTIVES

To assess the magnetic resonance imaging (MRI) appearance of renal masses after laparoscopic cryoablation.

METHODS

Between October 2000 and June 2004, 33 patients underwent laparoscopic cryoablation of 34 renal masses, 24 of whom (25 renal masses, size range 1.5 to 3.7 cm, mean 2.4) were followed up with MRI postoperatively. Postoperative MRI was done at 1, 3, and 6 months after ablation and every 6 months thereafter using a 1.5-T MRI scanner. T1-weighted dual-phase, coronal T1-weighted fat-saturated, and T2-weighted coronal and axial MRI was done before contrast administration. Postenhancement images were obtained in the coronal and axial planes during the arterial, venous, and delayed phases.

RESULTS

Patient follow-up data were available for at least 6 months and up to 48 months for 18 patients. On the first follow-up MRI study, six lesions had increased in size, five had decreased in size, and seven showed no change. Of the 18 patients, 7 had peripheral rim enhancement within 3 months of follow-up. Four resolved. One patient developed rim enhancement at 7 months postoperatively. Subsequent images revealed lesion enlargement with heterogeneous enhancement. Biopsy was positive for renal cell carcinoma. One patient developed nodular enhancement at 10 months with a decrease in lesion size. Watchful waiting was chosen because the patient had significant medical comorbidities.

CONCLUSIONS

Peripheral rim enhancement is a common finding on MRI immediately after laparoscopic renal cryoablation. Rim enhancement with an increase in lesion size or nodular enhancement is of more concern than rim enhancement alone. More data are necessary to understand the progression of renal lesions after cryoablation.

A floating sleeve antenna yields localized hepatic microwave ablation

We report a novel coaxial antenna for hepatic microwave ablation. This device uses a floating sleeve, that is, a metal conductor electrically isolated from the outer connector of the antenna coaxial body, to achieve a highly localized specific absorption rate pattern that is independent of insertion depth. This floating sleeve coaxial dipole antenna has low power reflection in the 2.4-GHz IMS band. Ex vivo experiments confirm our numerical simulation results. Index Terms-Ablation, coaxial aperture antennas, finite element methods, floating sleeve, microwave heating.

Outcome after hepatic resection versus combined resection and microwave ablation for multiple bilobar colorectal metastases to the liver

BACKGROUND

We investigated the efficacy of microwave ablation plus hepatectomy for multiple bilobar colorectal metastases to the liver. No consensus exists concerning local ablation plus hepatic resection for treating multiple bilobar colorectal liver metastases, partly because of a lack of long-term comparative survival data.

METHODS

Clinicopathologic data were analyzed retrospectively for 53 consecutive patients with 5 or more bilobar liver metastases from colorectal cancer who underwent hepatectomy with or without microwave ablation. Outcome measures were recurrence rate, recurrence pattern, and survival.

RESULTS

Combined resection/ablation was performed more frequently in patients with more liver metastases (P = .03). No significant differences were found for overall, disease-free, or hepatic recurrence-free survival between 16 patients with resection/ablation and 37 patients with resection (P = .43, .54, and .86, respectively). Multivariate analysis selected prehepatectomy carcinoembryonic antigen concentration in serum as an independent prognosticator for survival (P = .02), but not resection/ablation versus resection. In patients with combined resection/ablation, recurrence occurred near the resection or ablation line in only 2 patient (22%), whereas multiple neoplasms (>/=4) was the most common liver recurrence pattern (78%).

CONCLUSIONS

Microwave ablation plus hepatic resection expanded indications for operation to treat multiple bilobar liver metastases, with survival similar to that in less-involved hepatic resection patients.

The imprint of radiofrequency in the management of hepatocellular carcinoma

BACKGROUND

This article reviews the current results of radiofrequency application in the management of hepatocellular carcinoma (HCC) with reference to the comparison between the different surgical modalities.

METHOD

An electronic search was performed for studies on the treatment of HCC.

RESULTS

Thermoablation by means of radiofrequency (RFA), microwave coagulation therapy (MCT) and laser-induced thermotherapy (LITT) provides tumor necrosis with a low complication rate. These methods are still not predictable and it is difficult to monitor the extent of necrosis in a real-time manner. Combined transarterial embolization and RF ablation is a promising strategy for large HCCs. Radiofrequency-assisted liver resection is unique and has become very popular recently because it permits parenchymal transection with minimal blood loss.

CONCLUSION

Many alternative techniques have been applied recently for the management of HCC but their exact roles need to be defined by randomized studies. Advances in technology and refinements in technique may provide an effective and predictable way to ablate liver tumors using radiofrequency devices.

Bipolar radiofrequency ablation of liver metastases during laparotomy. First clinical experiences with a new multipolar ablation concept

BACKGROUND AND OBJECTIVE

Radiofrequency ablation (RFA) is a promising method for local treatment of liver malignancies. Currently available systems for radiofrequency ablation use monopolar current, which carries the risk of uncontrolled electrical current paths, collateral damages and limited effectiveness. To overcome this problem, we used a newly developed internally cooled bipolar application system in patients with irresectable liver metastases undergoing laparotomy. The aim of this study was to clinically evaluate the safety, feasibility and effectiveness of this new system with a novel multipolar application concept.

PATIENTS AND METHODS

Patients with a maximum of five liver metastases having a maximum diameter of 5 cm underwent laparotomy and abdominal exploration to control resectability. In cases of irresectability, RFA with the newly developed bipolar application system was performed. Treatment was carried out under ultrasound guidance. Depending on tumour size, shape and location, up to three applicators were simultaneously inserted in or closely around the tumour, never exceeding a maximum probe distance of 3 cm. In the multipolar ablation concept, the current runs alternating between all possible pairs of consecutively activated electrodes with up to 15 possible electrode combinations. Post-operative follow-up was evaluated by CT or MRI controls 24-48 h after RFA and every 3 months.

RESULTS

In a total of six patients (four male, two female; 61-68 years), ten metastases (1.0-5.5 cm) were treated with a total of 14 RF applications. In four metastases three probes were used, and in another four and two metastases, two and one probes were used, respectively. During a mean ablation time of 18.8 min (10-31), a mean energy of 48.8 kJ (12-116) for each metastases was applied. No procedure-related complications occurred. The patients were released from the hospital between 7 and 12 days post-intervention (median 9 days). The post-interventional control showed complete tumour ablation in all cases.

CONCLUSIONS

Bipolar radiofrequency using the novel multipolar ablation concept permits a safe and effective therapy for the induction of large volumes of coagulation in the local treatment of liver metastases.

In-vivo evaluation of a novel bipolar radiofrequency device for interstitial thermotherapy of liver tumors during normal and interrupted hepatic perfusion

BACKGROUND

Only monopolar systems have thus far been available for radiofrequency ablation of liver tumors, whose application is restricted because of the incalculable energy flow, reduction of electrical tissue conduction, and limited lesion size. The aim of this study was to evaluate a novel internally cooled bipolar radiofrequency application device under in vivo conditions and to compare the effect of this system on lesion size when combined with hepatic arterial microembolization or complete hepatic blood flow occlusion.

MATERIALS AND METHODS

In a porcine liver model, RFA (60 W, 12 min) was performed with either normal (n = 12), partially interrupted (arterial microembolization via a hepatic artery catheter n = 12) or completely interrupted hepatic perfusion (Pringle's maneuver, n = 12). RFA parameters (impedance, power output, temperature, applied energy) were determined continuously during therapy. RFA lesions were macroscopically assessed after liver dissection.

RESULTS

Bipolar RFA induced clinical relevant ellipsoid thermal lesions without complications. Hepatic inflow occlusion led to a 4.3-fold increase in lesion volume after arterial microembolization and a 5.8-fold increase after complete interruption (7.4 cm(3)versus 31.9 cm(3)versus 42.6 cm(3), P < 0.01).

CONCLUSIONS

The novel bipolar RFA device is a safe and effective alternative to monopolar RFA-systems. Interrupting hepatic perfusion significantly increases lesion volumes in bipolar RFA. This beneficial effect can also be achieved in the percutaneous application mode by RFA combined with arterial microembolization via a hepatic artery catheter.

Miniaturized ultrasound arrays for interstitial ablation and imaging

A potential alternative to extracorporeal, noninvasive HIFU therapy is minimally invasive intense ultrasound ablation that can be performed laparoscopically or percutaneously. An approach to minimally invasive ablation of soft tissue using miniaturized linear ultrasound arrays is presented here. Recently developed 32-element arrays with aperture 2.3 x 49 mm, therapy frequency 3.1 MHz, pulse-echo bandwidths >42% and surface acoustic energy density >80 W/cm2, are described. These arrays are integrated into a probe assembly, including a coupling balloon and piercing tip, suitable for interstitial ablation. An integrated electronic control system allows therapy planning and automated treatment guided by real-time interstitial B-scan imaging. Image quality, challenging because of limited probe dimensions and channel count, is aided by signal processing techniques that improve image definition and contrast, resulting in image quality comparable to typical transabdominal ultrasound imaging. Ablation results from ex vivo and in vivo experiments on mammalian liver tissue show that this approach is capable of ablation rates and volumes relevant to clinical applications of soft tissue ablation such as treatment of liver cancer.

Adverse effects of radiofrequency ablation of liver tumours in the Netherlands

BACKGROUND

Radiofrequency ablation (RFA) is a new treatment for liver tumours. Complications encountered after RFA in the Netherlands were evaluated in the present study.

METHODS

Between June 1999 and November 2003 patients undergoing RFA of irresectable liver tumours in eight medical centres were registered prospectively.

RESULTS

One hundred and forty-three RFA procedures were performed in 122 patients. RFA was combined with partial hepatectomy in 37 instances. Death occurred after two procedures (1.4 per cent), and was mainly due to concomitant partial hepatectomy. A total of 19 major complications occurred after ten procedures, including biliary tract damage (seven patients), liver failure (four), hepatic abscess (three), peritoneal infection (two), intrahepatic haematoma (one), hepatic artery aneurysm (one) and pulmonary embolism (one). Twenty-four minor complications were related to concomitant partial hepatectomy or laparotomy. The overall complication rate was 20.3 per cent and the rate of complications related directly to RFA was 9.8 per cent.

CONCLUSION

The procedure-specific complication rate was almost 10 per cent and it is recommended that RFA should be performed only by an experienced team comprising a hepatobiliary surgeon, gastroenterologist, hepatologist and interventional radiologist. Biliary stricture, hepatic vascular damage and hepatic abscesses were the most common major complications.

H19 expression in hepatic metastases from a range of human carcinomas

AIMS

To investigate the expression of the imprinted oncofetal H19 gene in hepatic metastases derived from a range of human carcinomas and assess its prognostic value with the view of developing a DNA based treatment for such metastases.

METHODS

Non-radioactive in situ hybridisation for H19 RNA was performed on paraffin wax embedded sections of liver biopsies or partial hepatectomy specimens, taken from 80 patients with hepatic metastases derived from carcinomas from several medical centres in Israel. The degree of expression was graded qualitatively according to the number of cells expressing H19 and the intensity of staining. The medical files were searched for demographic data and survival times before and after diagnosis of hepatic metastases.

RESULTS

H19 expression was found in the hepatic metastases of 64 of 80 patients. High expression (higher staining grades) of H19 in the metastases was found in 43 of 80 patients. However, H19 expression status in the hepatic metastases did not correlate with either the length of time to development of metastasis or overall survival.

CONCLUSIONS

H19 is highly expressed in more than half of hepatic metastases derived from a range of carcinomas. Thus, these metastases may be suitable candidates for H19 DNA based treatment. Further studies are needed to determine whether H19 expression has prognostic value in metastatic liver disease using larger numbers of specific subtypes of primary carcinomas.

The effect of hepatic blood inflow occlusion on hepatic cancer treated with diode-laser thermocoagulation

OBJECTIVE

To assess the effect of temporary occlusion of hepatic blood inflow on hepatic cancer treated with diode-laser induced thermocogation (LITT).

METHODS

The carcinoma Walker-256 was implanted in 40 SD rat livers. Twelve days later, the animals were randomly divided into 4 groups. Group A received LITT alone; group B received hepatic artery temporary occlusion during LITT; group C received portal vein temporary occlusion during LITT; group D received hepatic artery and portal vein temporary occlusion during LITT. Tumors were exposed to 810 nm diode-laser light at 0.95 watts for 10 min from a scanner tip applicator placed in the tumor. At the same time, the intrahepatic temperature distribution in rats with liver tumors was measured per 2 min during thermocoagulation. Tumor control was examined immediately 7 and 14 d after thermocoagulation.

RESULTS

There was significant difference of intrahepatic temperature distribution in rats with liver tumors among the 4 groups (P<0.05) except when group C samples were compared with group D samples at each time point, and group B samples were compared with group C samples at 120 s (P>0.05). Light microscopic examination of the histologic section samples revealed three separate zones: regular hyperthermic coagulation necrosis zone, transition zone and reference zone. Compared with the samples in group A and group B, group C and group D samples had more clear margin among the three zones.

CONCLUSION

The hepatic blood inflow occlusion, especially portal vein hepatic blood inflow occlusion, or all hepatic blood inflow occlusion considerably increased the efficacy of LITT in the treatment of liver cancer.

Radiofrequency ablation for malignant liver tumor

Radiofrequency ablation (RFA) has been widely practiced to treat unresectable malignant liver tumors. It has the merits of localized tumor ablation and preservation of maximal normal liver parenchyma. In recent years, there has been a tremendous expansion in the application of RFA for patients with malignant liver tumors. However, the therapeutic effect of this local ablation treatment needs to be balanced against its risks and possible local failure. This review focuses on the current status of RFA for malignant liver tumors, with special attention to the indication, approaches, complications, survival benefits, combination therapies, and comparison with other treatment modalities. Although the results of most clinical studies of RFA seem favorable, the associated risks and tumor recurrence should not be underestimated. Careful patient selection, meticulous RFA techniques, and prompt treatment of residual and recurrent tumors are necessary to ensure a better outcome after RFA. Until recently, there has been no strong evidence showing that RFA can replace any other treatment modalities in the management of liver tumors. Nonetheless, more convincing evidence by randomized trials is required for the establishment of a treatment protocol of RFA for patients with malignant liver tumors.