Which patients will benefit from percutaneous radiofrequency ablation of colorectal liver metastases? Critically appraised topic

Practical utility of liver segmentation methods in clinical surgeries and interventions

Clinical imaging (e.g., magnetic resonance imaging and computed tomography) is a crucial adjunct for clinicians, aiding in the diagnosis of diseases and planning of appropriate interventions. This is especially true in malignant conditions such as hepatocellular carcinoma (HCC), where image segmentation (such as accurate delineation of liver and tumor) is the preliminary step taken by the clinicians to optimize diagnosis, staging, and treatment planning and intervention (e.g., transplantation, surgical resection, radiotherapy, PVE, embolization, etc). Thus, segmentation methods could potentially impact the diagnosis and treatment outcomes. This paper comprehensively reviews the literature (during the year 2012-2021) for relevant segmentation methods and proposes a broad categorization based on their clinical utility (i.e., surgical and radiological interventions) in HCC. The categorization is based on the parameters such as precision, accuracy, and automation.

Percutaneous Cholecystostomy and Hydrodissection in Radiofrequency Ablation of Liver Subcapsular Leiomyosarcoma Metastasis Adjacent to the Gallbladder: Protective Effect

Uterine leiomyosarcoma is an uncommon pathology, predominantly found in aged population. Patients with metastatic disease have poor survival and therapy mainly consists of palliative systemic chemotherapy. However, more aggressive strategies such as radiofrequency ablation (RFA) may benefit patients with limited secondary disease. RFA is considered a simple and safe modality for treatment of hepatic lesions. The benefits related to RFA include low morbidity, short hospital stay and the possibility to repeat the procedure when necessary due to recurrences. However, minor and major complications related to mechanical and thermal damage may occur, especially in cases of tumors adjacent to extrahepatic organs and those at subcapsular position. This case report shows a successful RFA of two hepatic subcapsular leiomyosarcoma metastases neighbouring the gallbladder, without a safe cleavage plane from it. Combined hydrodissection, percutaneous cholecystostomy and continuous irrigation were performed as effective techniques to prevent thermal injury. Clinical and radiological follow up demonstrates no local complication.

Risk Factors for Bile Duct Injury After Percutaneous Thermal Ablation of Malignant Liver Tumors: A Retrospective Case-Control Study

BACKGROUND

Bile duct injury after ablation of malignant liver tumors (MLTs) was not unusual and should be avoided. However, few studies have focused on evaluating the risk factors for intrahepatic bile duct injury.

AIM

To evaluate the risk factors for intrahepatic bile duct injury after ablation of MLTs and to evaluate the minimum safe distance for ablating tumors abutting bile ducts.

METHODS

Sixty-five patients with intrahepatic bile duct injury after ablation of MLTs, and 65 controls were recruited. Risk factors for intrahepatic bile duct injury were analyzed. Tumor location was recorded as ≤5 mm (group A), 5-10 mm (group B), and >10 mm (group C) from the right/left main duct or segmental bile duct.

RESULTS

Ascites history (P < 0.001), TACE treatment history (P = 0.025), intrahepatic bile duct dilatation before ablation (P < 0.001), and tumor location (P = 0.000) were identified as significant risk factors for intrahepatic bile duct injury. Significant differences in the risk of intrahepatic bile duct injury were found between groups B and C (P = 0.000), but not between groups A and B (P = 0.751). Ascites history (P = 0.002) and tumor location (P < 0.001) were independent predictors with the OR (95 % confidence interval) of 39.31(3.95-391.69) and 16.56 (5.87-46.71), respectively.

CONCLUSIONS

Bile duct injury after ablation of MLTs was the result of local treatment-related factors combined with the patients' general condition. The minimum safe distance for ablation of tumor abutting a bile duct was 10 mm.

[The six steps necessary in elaborating critically appraised topics]

Different types of critically appraised topics (CATs) can be elaborated in diagnostic imaging: comparison of diagnostic tests, evaluation of techniques for early detection (screening), economical analyses, or therapeutic aspects, among others. Their design will vary in function of the question they aim to answer. For example, for treatment evaluation, clinical trials are the best, but if there are secondary studies (systematic reviews or meta-analyses) that synthesize information from several studies, the results will be more important and the scientific conclusions will be more relevant. Regardless of the study design used, the elaboration of a CAT will involve six steps: 1) question; 2) systematic and efficient bibliographic search; 3) levels of evidence (choosing the articles that have the best level); 4) critical reading of the articles chosen; 5) applying conclusions to the context, and 6) recommendations. In this article, we will describe these steps and the nuances for different types of studies in each step.

MAFR. Complications of radiofrequency ablation of hepatic tumors: Frequency and risk factors

Radiofrequency ablation (RFA) has become an important option in the therapy of primary and secondary hepatic tumors. Surgical resection is still the best treatment option, but only a few of these patients are candidates for surgery: multilobar disease, insufficient liver reserve that will lead to liver failure after resection, extra-hepatic disease, proximity to major bile ducts and vessels, and co-morbidities. RFA has a low mortality and morbidity rate and is considered to be safe. Thus, complications occur and vary widely in the literature. Complications are caused by thermal damage, direct needle injury, infection and the patient’s co-morbidities. Tumor type, type of approach, number of lesions, tumor localization, underlying hepatic disease, the physician’s experience, associated hepatic resection and lesion size have been described as factors significantly associated with complications. The physician in charge should promptly recognize high-risk patients more susceptible to complications, perform a close post procedure follow-up and manage them early and adequately if they occur. We aim to describe complications from RFA of hepatic tumors and their risk factors, as well as a few techniques to avoid them. This way, others can decrease their morbidity rates with better outcomes.

Diaphragmatic hernia after lung percutaneous radiofrequency ablation: incidence and risk factors

PURPOSE

To evaluate diaphragmatic hernias (DH) after percutaneous radiofrequency ablation (PRFA) for basal lung nodules and to detect risk factors.

MATERIALS AND METHODS

Between January 2009 and December 2012, the presence of DH was retrospectively recorded in all of the patients who underwent PRFA with multitine expandable electrodes for ablation of nodules in the lower lobe. All nodules were classified into three groups according to the location of the tines after deployment relative to the diaphragm: In group 1, the tines were at a distance of >1 cm from the diaphragm; in group 2, at least one tine was in contact with the diaphragm without perforation; and in group 3, at least one tine was perforating the diaphragm.

RESULTS

We recorded 4 cases of DH (3 on the left side, 1 on the right side) in 156 patients (2.3% of procedures). The delay of onset was 7.8 months. DH occurred in groups 2 (n = 1) and 3 (n = 3). Only the 3 cases that occurred on the left side were symptomatic (2 intussusceptions and 1 gastroesophageal reflux) and were surgically repaired. The electrode was positioned in the center of the diaphragm in all cases.

CONCLUSION

The central position of the electrode and the contact of at least one tine with the diaphragm after deployment seem to be a risk factor to develop DH.

[Critically appraised topics (CATs): a new publishing opportunity in Radiología]

Physicians need fast access to quality information about the best diagnostic tests and treatments in each case. To meet this need, a new publishing format has emerged. Critically appraised topics (CATs) are elaborated following the five steps of evidence-based medicine. CATs are structured summaries of research articles that deal with a specific clinical query, presenting a critical evaluation of the best evidence available to support the validity of the available options. CATs have proven useful in teaching evidence-based radiology and this publishing format is becoming more common. Radiology CATs can be found on medical websites and in journals, including those dedicated to general medicine as well as those specifically dedicated to radiology. Radiología encourages the publication of CATs because we consider that they can be useful for daily decision making.

How to write a critically appraised topic (CAT)

Medical knowledge and the volume of scientific articles published have expanded rapidly over the past 50 years. Evidence-based practice (EBP) has developed to help health practitioners get more benefit from the increasing volume of information to solve complex health problems. A format for sharing information in EBP is the critically appraised topic (CAT). A CAT is a standardized summary of research evidence organized around a clinical question, aimed at providing both a critique of the research and a statement of the clinical relevance of results. In this review, we explain the five steps involved in writing a CAT for a clinical purpose ("Ask," "Search," "Appraise," "Apply," and "Evaluate") and introduce some of the useful electronic resources available to help in creating CATs.

Bimodal electric tissue ablation (BETA)--effect of reversing the polarity of the direct current on the size of ablation

BACKGROUND

Bimodal electric tissue ablation (BETA) is a new technique that uses the direct current in electrolysis to improve the efficacy of radio frequency (RF) ablation. It was hypothesized that attaching the cathode of the electrolytic circuit to the RF electrode will increase the tissue hydration, therefore delaying tissue desiccation during ablation. Consequently, the ablation process can continue for a longer period of time and produce larger ablations. This hypothesis was tested by reversing the polarity of the electrolytic circuit, which theoretically would cause tissue desiccation and therefore produce smaller ablations. This new setup is called reversed polarity bimodal electric ablation (RP-BEA).

MATERIALS AND METHODS

Three types of ablations standard radiofrequency ablation (RFA), BETA, and RP-BEA) were tested in a pig liver model. In BETA and RP-BEA, 9 V of direct current were provided for 10 min, after which the rf generator were switched on and both electrical circuits allowed to run concurrently. In all three setups, ablations were continued until "roll-off." The size of ablation was measured and compared with each other.

RESULTS

The duration of ablation was significantly shorted in RP-BEA compared with standard RFA and BETA (48 s verus 148 s and 84 s, respectively, P = 0.004). The sizes of ablations in RP-BEA were also significantly smaller compared with standard RFA and BETA-skin.

CONCLUSION

RP-BEA caused tissue desiccation resulting in a shorter duration of ablation and smaller ablations. Therefore, the theory that BETA increases ablation size due to the effects of increased tissue hydration around the rf electrode is correct.

Lack of Anatomical Concordance between Preablation and Postablation CT Images: A Risk Factor Related to Ablation Site Recurrence

Objective. Variation in the position of the liver between preablation and postablation CT images hampers assessment of treatment of colorectal liver metastasis (CRLM). The aim of this study was to test the hypothesis that discordant preablation and postablation imaging is associated with more ablation site recurrences (ASRs). Methods. Patients with CRLM were included. Index-tumor size, location, number, RFA approachs and ablative margins were obtained on CT scans. Preablation and postablation CT images were assigned a "Similarity of Positioning Score" (SiPS). A suitable cutoff was determined. Images were classified as identical (SiPS-id) or nonidentical (SiPS-diff). ASR was identified prospectively on follow-up imaging. Results. Forty-seven patients with 97 tumors underwent 64 RFA procedures (39 patients/63 tumors open RFA, 25 patients/34 tumours CT-targeted RFA, 12 patients underwent >1 RFA). Images of 52 (54%) ablation sites were classified as SiPS-id, 45 (46%) as SiPS-diff. Index-tumor size, tumor location and number, concomitant partial hepatectomy, and RFA approach did not influence the SiPS. ASR developed in 11/47 (23%) patients and 20/97 (21%) tumours. ASR occurred less frequently after open RFA than after CT targeted RFA (P < 0.001). ASR was associated with larger index-tumour size (18.9 versus 12.8 mm, P = 0.011). Cox proportional hazard model confirmed SiPS-diff, index-tumour size >20 mm and CT-targeted RFA as independent risk factors for ASR. Conclusion. Variation in anatomical concordance between preablation and postablation images, index-tumor size, and a CT-targeted approach are risk factors for ASR in CRLM.

Value-based insurance design: barriers to implementation in radiology

Expensive and steadily rising health care costs without a concomitant increase in quality have generated a search for solutions to fund health care in the United States. Recent health care reforms and proposals on the agenda have spurred debate about alternative payment plans for health care. Much of the talk centers on imaging, which is a fast-growing and expensive component of health care. Value-based insurance design (VBID), a "clinically sensitive" means of sharing the cost of health care, has been proposed as a means to control the runaway costs of health care management including diagnostic testing. A corollary of pay-for-performance initiatives in which physician incentives are aligned with evidence-based medical practices, VBID seeks to increase patient incentives to comply with evidence-based health care consumption. We previously reviewed the principles of VBID and provided examples of VBID in practice using diabetes management as a model, as well as suggested some areas in diagnostic testing that lend themselves to VBID benefit design. In this article, we summarize the barriers to implementation and outline potential solutions, with particular regard to radiology.

Radiofrequency ablation of liver tumors: Actual limitations and potential solutions in the future

Over the past decade, radiofrequency ablation (RFA) has evolved into an important therapeutical tool for the treatment of non resectable primary and secondary liver tumors. The clinical benefit of RFA is represented in several clinical studies. They underline the safety and feasibility of this new and modern concept in treating liver tumors. RFA has proven its clinical impact not only in hepatocellular carcinoma (HCC) but also in metastatic disease such as colorectal cancer (CRC). Due to the increasing number of HCC and CRC, RFA might play an even more important role in the future. Therefore, the refinement of RFA technology is as important as the evaluation of data of prospective randomized trials that will help define guidelines for good clinical practice in RFA application in the future. The combination of hepatic resection and RFA extends the feasibility of open surgical procedures in patients with extensive tumors. Adverse effects of RFA such as biliary tract damage, liver failure and local recurrence remain an important task today but overall the long term results of RFA application in treating liver tumors are promising. Incomplete ablation of liver tumors due to insufficient technology of ablation needles, tissue cooling by the neighbouring blood vessels, large tumor masses and ablation of tumors in close vicinity to heat sensitive organs remain difficult tasks for RFA. Future solutions to overcome these limitations of RFA will include refinement of ultrasonographic guidance (accuracy of probe placement), improvements in needle technology (e.g. needles preventing charring) and intraductal cooling techniques.

Lung tumors treated with percutaneous radiofrequency ablation: computed tomography imaging follow-up

PURPOSE

To describe the morphologic evolution of lung tumors treated with radiofrequency ablation (RFA) by way of computed tomography (CT) images and to investigate patterns of incomplete RFA at the site of ablation.

MATERIALS AND METHODS

One hundred eighty-nine patients with 350 lung tumors treated with RFA underwent CT imaging at 2, 4, 6, and 12 months. CT findings were interpreted separately by two reviewers with consensus. Five different radiologic patterns were predefined: fibrosis, cavitation, nodule, atelectasis, and disappearance. The appearance of the treated area was evaluated at each follow-up CT using the predefined patterns.

RESULTS

At 1 year after treatment, the most common evolutions were fibrosis (50.5%) or nodules (44.8%). Differences were noted depending on the initial size of the tumor, with fibrosis occurring more frequently for tumors <2 cm (58.6% vs. 22.9%, P = 1 × 10(-5)). Cavitation and atelectasis were less frequent patterns (2.4% and 1.4%, respectively, at 1 year). Tumor location (intraparenchymatous, with pleural contact <50% or >50%) was not significantly correlated with follow-up image pattern. Local tumor progressions were observed with each type of evolution. At 1 year, 12 local recurrences were noted: 2 cavitations, which represented 40% of the cavitations noted at 1 year; 2 fibroses (1.9%); 7 nodules (7.4%); and 1 atelectasis (33.3%).

CONCLUSION

After RFA of lung tumors, follow-up CT scans show that the shape of the treatment zone can evolve in five different patterns. None of these patterns, however, can confirm the absence of further local tumor progression at subsequent follow-up.

A systematic review on the clinical benefit and role of radiofrequency ablation as treatment of colorectal liver metastases

AIM

To evaluate the role of radiofrequency ablation (RFA) as treatment of colorectal cancer liver metastases (CLMs).

METHOD

A PubMed literature search for original articles published until August 2008 was performed. Studies with 40 patients, 18 month median follow-up and reported 3 year overall survival (OS) rates after RFA of CLM were selected for analysis.

RESULTS

Thirteen clinical series and 8 non-randomised comparative studies were analysed. Median progression free survival after RFA ranged between 6 and 13 months. Median and 5-year OS after RFA (RFA plus resection) ranged between 24-59 months and 18-40% (36-46 months and 27-30%). Comparative studies indicated significantly improved OS after RFA versus chemotherapy alone, RFA plus chemotherapy versus RFA alone and up-front RFA versus RFA following second-line chemotherapy.

CONCLUSION

Our findings support that RFA prolongs time without toxicity and survival as an adjunct to hepatectomy and/or chemotherapy in well-selected patients, but not as an alternative to resection.

Intra-arterial hepatic chemotherapy for unresectable colorectal liver metastases: a review of medical devices complications in 3172 patients

Background

Hepatic artery infusion (HAI) is indicated to treat unresectable colorectal hepatic metastases, with recent applications as a neoadjuvant or adjuvant treatment. Traditionally performed with the infusion of fluoropyrimidine-based chemotherapy, it has been now tested with oxaliplatin or irinotecan and associated with systemic chemotherapy.

Methods

To evaluate the impact of medical devices complications we carried out a search of the published studies on HAI in unresectable colorectal liver metastases. Complications were pooled according to the applied medical system: 1) surgical catheter, 2) radiological catheter, and 3) fully implantable pump. The surgical catheter is inserted into the hepatic artery from the gastro-duodenal artery. The radiological catheter is inserted into the hepatic artery through a percutaneous transfemoral or transaxillar access. The fully implantable pump is a totally internal medical device connected to the arterial hepatic catheter during laparotomy.

Results

The selection criteria were met in 47/319 studies. The complications of surgical and radiological medical devices connected to a port were found in 16 and 14 studies respectively. Meanwhile, complications with a fully implantable pump were reported in 17 studies. The total number of complications reported in studies evaluating patients with surgical or radiological catheter were 322 (322/948, 34%) and 261 (261/722, 36.1%) respectively. In studies evaluating patients with a fully implantable pump, the total number of complications was 237 (237/1502, 15.8%). In 18/319 studies the number of cycles was reported. The median number of cycles with surgically and radiologically implanted catheters was 8 and 6 respectively. The fully implantable pump allows a median number of 12 cycles.

Conclusions

The fully implantable pump, maintaining a continuous infusion through the system, allows the lowest risk for thrombosis and infection and the best median number of cycles of loco-regional chemotherapy in HAI.