Stefaan Mulier

Local recurrence after hepatic radiofrequency coagulation: multivariate meta-analysis and review of contributing factors.

Objective:The purpose of this study was to analyze the factors that influence local recurrence after radiofrequency coagulation of liver tumors. Summary Background Data:Local recurrence rate varies widely between 2% and 60%. Apart from tumor size as an important risk factor for local recurrence, little is known about the impact of other factors. Methods:An exhaustive literature search was carried out for the period from January 1, 1990 to January 1, 2004. Only series with a minimal follow-up of 6 months and/or mean follow-up of 12 months were included. Univariate and multivariate meta-analyses were carried out. Results:Ninety-five independent series were included, allowing the analysis of the local recurrence rate of 5224 treated liver tumors. In a univariate analysis, tumor-dependent factors with significantly less local recurrences were: smaller size, neuroendocrine metastases, nonsubcapsular location, and location away from large vessels. Physician-dependent favorable factors were: surgical (open or laparoscopic) approach, vascular occlusion, general anesthesia, a 1-cm intentional margin, and a greater physician experience. In a multivariate analysis, significantly less local recurrences were observed for small size (P < 0.001) and a surgical (versus percutaneous) approach (P < 0.001). Conclusions:Radiofrequency coagulation by laparoscopy or laparotomy results in superior local control, independent of tumor size. The percutaneous route should mainly be reserved for patients who cannot tolerate a laparoscopy or laparotomy. The short-term benefits of less invasiveness for the percutaneous route do not outweigh the longer-term higher risk of local recurrence.

Radiofrequency Ablation Versus Resection for Resectable Colorectal Liver Metastases: Time for a Randomized Trial?

BackgroundSurgical resection is the gold standard in the treatment of resectable colorectal liver metastases (CRLM). In several centers, resection is being replaced by radiofrequency ablation (RFA), even though there is no evidence yet from randomized trials to support this. The aim of this study was to critically review the oncological evidence for and against the use of RFA for resectable CRLM.MethodsAn exhaustive review of RFA of colorectal metastases was carried out.ResultsFive-year survival data after RFA for resectable CRLM are not available. Percutaneous RFA is associated with worse local control, worse staging, and a small risk of electrode track seeding when compared with resection (level V evidence). For tumors ≤3 cm, local control after surgical RFA is equivalent to resection, especially if applied by experienced physicians to nonperivascular tumors (level V evidence). There is indirect evidence for profoundly different biological effects of RFA and resection.ConclusionsA subgroup of patients has been identified for whom local control after RFA might be equivalent to resection. Whether this is true, and whether this translates into equivalent survival, remains to be proven. The time has come for a randomized trial.

Factors affecting mortality in generalized postoperative peritonitis: multivariate analysis in 96 patients.

Mortality of generalized postoperative peritonitis remains high at 22% to 55%. The aim of the present study was to identify prognostic factors by means of univariate and multivariate analysis in a consecutive series of 96 patients. Mortality was 30%. Inability to clear the abdominal infection or to control the septic source, older age, and unconsciousness were significant factors related to mortality in the multivariate analysis. Failure to control the peritoneal infection (15%) was always fatal and correlated with failed septic source control, high Acute Physiology and Chronic Health Evaluation (APACHE) II score, and male gender. Failure to control the septic source (8%) also was always fatal and correlated with high APACHE II score and therapeutic delay. In patients with immediate source control, residual peritonitis occurred in 9% after purulent or biliary peritonitis and in 41% after fecal peritonitis (p = 0.002). In patients without immediate control of the septic source, delayed control was still achieved in 100% after a planned relaparotomy (PR) strategy versus 43% after an on-demand relaparotomy (ODR) strategy (p = 0.018). In the same patients, mortality was 0% in the PR group versus 64% in the ODR group (p = 0.007). Early relaparotomy is related to improved septic source control. After relaparotomy for generalized postoperative peritonitis, a PR strategy is indicated whenever source control is uncertain. It also might decrease mortality in fecal peritonitis. An ODR approach is adequate for purulent and biliary peritonitis with safe septic source control.

A review of the general aspects of radiofrequency ablation

As an alternative to standard surgical resection for the treatment of malignant tumors, radiofrequency ablation (RFA) has rapidly evolved into the most popular minimally invasive therapy. To help readers gain the relevant background knowledge and to better understand the other reviews in this Feature Section on the clinical applications of RFA in different abdominal organs, the present report covers the general aspects of RFA. After an introduction, we present a simple definition of the energy applied during RFA, a brief historical review of its technical evolution, and an explanation of the mechanism of action of RFA. These basic discussions are substantiated with descriptions of RFA equipment including those commercially available and those under preclinical development. The size and geometry of induced lesions in relation to RFA efficacy and side effects are discussed. The unique pathophysiologic process of thermal tissue damage and the corresponding histomorphologic manifestations after RFA are detailed and cross-referenced with the findings in the current literature. The crucial role of imaging technology during and after RFA is also addressed, including some promising new developments. This report finishes with a summary of the key messages and a perspective on further technologic refinements and identifies some specific priorities.

Radiofrequency Ablation versus Resection for Resectable Colorectal Liver Metastases: Time for a Randomized Trial?

Background: A recent proposal of a randomized trial comparing resection and radiofrequency ablation (RFA) in a selected subgroup of patients with small resectable colorectal liver metastases (CRLM) has initiated a debate on this issue. Meanwhile, new data have been published. The aim of the study was to update and critically review the oncological evidence in favor of and against the use of RFA for resectable CRLM in general and in favor of and against conducting a randomized trial in a selected subgroup of patients. Methods: An exhaustive review was carried out of papers and abstracts on RFA of colorectal metastases published before July 15, 2008. Results: Local recurrence rate after resection of CRLM is 1.2–10.4%. Local recurrence rate after RFA of CRLM is between 1.7 and 66.7%. For tumors <3 cm, local control after open RFA is equivalent to resection. Local recurrence rates, however, are higher for larger tumors and for the percutaneous and laparoscopic route. Accumulating evidence suggests that RFA and resection induce profoundly different biological effects, which may influence survival. Conclusions: Local recurrence rate after open RFA for CRLM <3 cm seems to be equivalent to resection. A randomized trial under strict conditions would be justified in this subgroup of patients. A randomized trial is currently not justified for larger tumors or for percutaneous or laparoscopic RFA, since local recurrence rates in these groups are too high to be acceptable for resectable tumors.

Treatment of VX2 liver tumor in rabbits with "wet" electrode mediated radio-frequency ablation.

Abstract. Radio-frequency ablation (RFA) has been considered as an alternative therapy for liver tumors. A “wet” electrode with interstitial infusion of hypertonic saline was tested for the RFA of liver tumor in rabbits. Seventy-eight liver tumors (? 1.5 to 3.0 cm) were induced in 41 rabbits by VX2 carcinoma implantation. Fifty-one tumors in 27 rabbits were treated with RFA. Under laparotomy, the RF energy was delivered while 5 % saline was infused through the electrode into the tumor at 1 ml/min. Six rabbits with 12 tumors were treated with only intratumoral 5 % saline infusion without RFA. Another 8 rabbits with 15 tumors received sham operation as untreated controls. The efficacy of the therapy was evaluated with survival rate, MRI, microangiography, and histopathology. In the RFA group, 6 rabbits survived longer than 6 months (absolute eradication rate 22.2 %); 12 rabbits were found free of viable tumor at the moment when they were sacrificed (relative eradication rate 44.4 %); 9 rabbits showed local tumor relapse and/or lung metastasis 2–10 weeks after ablation (recurrent rate 33.3 %). In control groups of saline infusion and sham operation, all 14 rabbits died within 3 months (mortality rate 100 %). Three-month survival rates between RFA group and control groups were significantly different (p < 0.05). Findings of MRI, microangiography, and histology supported these outcomes. Radical treatment of liver malignancy in rabbits is possible with the present modified RFA technique. Its clinical usefulness has to be further proven.

Electrodes and multiple electrode systems for radiofrequency ablation: a proposal for updated terminology.

Research on technology for soft tissue radiofrequency (RF) ablation is ever advancing. A recent proposal to standardise terminology of RF electrodes only deals with the most frequently used commercial electrodes. The aim of this study was to develop a logical, versatile and unequivocal terminology to describe present and future RF electrodes and multiple electrode systems. We have carried out a PubMed search for the period from January 1 1990 to July 1 2004 in seven languages and contacted the six major companies that produce commercial RF electrodes for use in clinic. In a first step, names have been defined for the five existing basic designs of single-shaft electrode. These names had to be unequivocal, descriptive of the electrode’s main working principle and as short as possible. In a second step, these basic names have been used as building blocks to describe the single-shaft electrodes in combination designs. In a third step, using the same principles, a logical terminology has been developed for multiple electrode systems, defined as the combined use of more than one single-shaft RF electrode. Five basic electrode designs were identified and defined: plain, cooled, expandable, wet and bipolar electrodes. Combination designs included cooled–wet, expandable–wet, bipolar–wet, bipolar–cooled, bipolar–expandable and bipolar–cooled–wet electrodes. Multiple electrode systems could be characterised by describing several features: the number of electrodes that were used (dual, triple, ...), the electric mode (monopolar or bipolar), the activation mode (consecutive, simultaneous or switching), the site of the inserted electrodes (monofocal or multifocal), and the type of single shaft electrodes that were used. In this terminology, the naming of the basic electrode designs has been based on objective criteria. The short and unequivocal names of the basic designs can easily be combined to describe current and future combination electrodes. This terminology provides an exact and complete description of the versatile novel multiple electrode systems.

Experimental and clinical radiofrequency ablation: Proposal for standardized description of coagulation size and geometry

BackgroundRadiofrequency (RF) ablation is used to obtain local control of unresectable tumors in liver, kidney, prostate, and other organs. Accurate data on expected size and geometry of coagulation zones are essential for physicians to prevent collateral damage and local tumor recurrence. The aim of this study was to develop a standardized terminology to describe the size and geometry of these zones for experimental and clinical RF.MethodsIn a first step, the essential geometric parameters to accurately describe the coagulation zones and the spatial relationship between the coagulation zones and the electrodes were defined. In a second step, standard terms were assigned to each parameter.ResultsThe proposed terms for single-electrode RF ablation include axial diameter, front margin, coagulation center, maximal and minimal radius, maximal and minimal transverse diameter, ellipticity index, and regularity index. In addition a subjective description of the general shape and regularity is recommended.ConclusionsAdoption of the proposed standardized description method may help to fill in the many gaps in our current knowledge of the size and geometry of RF coagulation zones.

A novel "cooled-wet" electrode for radiofrequency ablation.

Abstract. In the light of growing demands for improved applicability of radiofrequency ablation (RFA), recently we have developed a novel “cooled-wet” electrode by taking the advantages of both internally cooled and saline-enhanced electrodes. The efficacy of the electrode was evaluated in both ex vivo and in vivo liver RFA under both low and high power output levels. The ablation volume created with the “cooled-wet” electrode appeared to be much larger than that reported up to now with the use of other monopolar electrodes. The mechanisms on how this device optimizes the RF energy delivery are also discussed.

Proliferative myositis in a child

Abstract A case of proliferative myositis in the lumbar paraspinal muscles in a 14-year-old boy is presented. Imaging investigations including plain radiograph, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), bone scan and positron emission tomography (PET) were suggestive of an inflammatory process such as myositis ossificans. The diagnosis was made by incisional biopsy. More pronounced edema, more muscle fiber necrosis and a higher cellularity were found compared to adult cases. The karyotype of the lesion was normal. Clinically, the mass disappeared spontaneously. After 24 months, asymptomatic bridging ossification between the third and fourth lumbar vertebrae was noted.