Radiologic appearance and complications of percutaneous computed tomography-guided radiofrequency-ablated pulmonary metastases from colorectal carcinoma

Device safety assessment of bronchoscopic microwave ablation of normal swine peripheral lung using robotic-assisted bronchoscopy

INTRODUCTION

The aim of this study was to assess the safety of bronchoscopic microwave ablation (MWA) of peripheral lung parenchyma using the NEUWAVE™ FLEX Microwave Ablation System, and robotic-assisted bronchoscopy (RAB) using the MONARCH™ Platform in a swine model.

METHODS

Computed tomography (CT)-guided RAB MWA was performed in the peripheral lung parenchyma of 17 Yorkshire swine (40-50 kg) and procedural adverse events (AEs) documented. The acute group (day 0, n = 5) received 4 MWAs at 100 W for 1, 3, 5, and 10 min in 4 different lung lobes. Subacute and chronic groups (days 3 and 30, n = 6 each) received one MWA (100 W, 10 min) per animal.

RESULTS

The study was completed without major procedural complications. No postprocedural AEs including death, pneumothorax, bronchopleural fistula, hemothorax, or pleural effusions were observed. No gross or histological findings suggestive of thromboembolism were found in any organ. One 3-Day and one 30-Day swine exhibited coughing that required no medication (minor AEs), and one 30-Day animal required antibiotic medication (major AE) for a suspected lower respiratory tract infection that subsided after two weeks. CT-based volumetric estimates of ablation zones in the acute group increased in an ablation time-dependent (1-10 min) manner, whereas macroscopy-based estimates showed an increasing trend in ablation zone size.

CONCLUSION

The NEUWAVE FLEX and MONARCH devices were safely used to perform single or multiple RAB MWAs. The preclinical procedural safety profile of RAB MWA supports clinical research of both devices to investigate efficacy in select patients with oligometastatic disease or primary NSCLC.

Long term survival after multiple microwave ablations for colorectal cancer lung metastases: A case report

Colorectal cancer is one of the leading causes of cancer-associated morbidity and mortality in the world, with lower survival rates when metastases are present. We present a case of a 69-year-old man, diagnosed with metastatic rectal cancer to the lungs in 2015. Over the course of 5 years, he was treated with 4 microwave ablation procedures to both his lungs. Despite this, he does not have any local recurrence or any symptoms since he was first diagnosed 7 years ago. This case highlights the potential for microwave ablation to be used for curative intent in pulmonary metastases in colorectal cancer as an alternative to more invasive and complex procedures such as metastasectomies or lung resection, as well as the benefit of using microwave ablation for disease control to improve patients’ quality of life.

Feasibility of diffusion-weighted magnetic resonance imaging in evaluation of early therapeutic response after CT-guided microwave ablation of inoperable lung neoplasms

Objective

To determine the early treatment response after microwave ablation (MWA) of inoperable lung neoplasms using the apparent diffusion coefficient (ADC) value calculated 24 h after the ablation.

Materials and methods

This retrospective study included 47 patients with 68 lung lesions, who underwent percutaneous MWA from January 2008 to December 2017. Evaluation of the lesions was done using MRI including DWI sequence with ADC value calculation pre-ablation and 24 h post-ablation. DWI-MR was performed with b values (50, 400, 800 mm²/s). The post-ablation follow-up was performed using chest CT and/or MRI within 24 h following the procedure; after 3, 6, 9, and 12 months; and every 6 months onwards to determine the local tumor response. The post-ablation ADC value changes were compared to the end response of the lesions.

Results

Forty-seven patients (mean age: 63.8 ± 14.2 years, 25 women) with 68 lesions having a mean tumor size of 1.5 ± 0.9 cm (range: 0.7–5 cm) were evaluated. Sixty-one lesions (89.7%) showed a complete treatment response, and the remaining 7 lesions (10.3%) showed a local progression (residual activity). There was a statistically significant difference regarding the ADC value measured 24 h after the ablation between the responding (1.7 ± 0.3 × 10⁻³ mm²/s) and non-responding groups (1.4 ± 0.3 × 10⁻³ mm²/s) with significantly higher values in the responding group (p = 0.001). A suggested ADC cut-off value of 1.42 could be used as a reference point for the post-ablation response prediction (sensitivity: 66.67%, specificity: 84.21%, PPV: 66.7%, and NPV: 84.2%). No significant difference was reported regarding the ADC value performed before the ablation as a factor for the prognosis of treatment response (p = 0.86).

Conclusion

ADC value assessment following ablation may allow the early prediction of treatment efficacy after MWA of inoperable lung neoplasms.

Key Points

• ADC value calculated 24 h post-treatment may allow the early prediction of MWA efficacy as a treatment of pulmonary tumors and can be used in the early immediate post-ablation imaging follow-up.

• The pre-treatment ADC value of lung neoplasms is not different between the responding and non-responding tumors.

Imaging of the thorax after percutaneous thermal ablation of lung malignancies

Image-guided thermal ablation is a minimally invasive treatment option for patients with early stage non-small cell lung cancer or metastatic disease to the lungs. Percutaneous ablation treats malignant tumours in situ, which precludes histopathological evaluation of the ablated tumours. Imaging studies are used as surrogates to assess technical and clinical success. Although it is not universally accepted, a common protocol for surveillance imaging includes contrast-enhanced computed tomography (CT) at 1, 3, 6, 9, 12, 18, 24 months, and yearly thereafter. Integrated 2-[¹⁸F]-fluoro-2-deoxy-d-glucose positron-emission tomography (PET)/CT imaging is recommended at 3 and 12 months and when recurrent disease is suspected. There is a complex evolution of the ablation zone on CT and PET imaging studies. The zone of ablation, initially larger than the ablated tumour, undergoes gradual involution. In the process, it may cavitate and resemble a lung abscess. Different contrast-enhancement and radionuclide uptake patterns in and around the ablation zone may indicate a wide range of diagnostic possibilities from a normal physiological response to local progression. Ultimately, the zone of ablation may be replaced by a variety of findings including linear bands of density, pleural thickening, or residual necrotic tumour. Diagnostic and interventional radiologists interpreting post-ablation imaging studies must have a clear understanding of the ablation process and imaging findings on surveillance studies. Accurate and timely recognition of complications and/or local recurrence is necessary to guide further therapy. The purpose of this article is to review imaging protocols and salient imaging findings after thermal ablation of lung malignancies.

Clinical outcomes of percutaneous thermal ablation for pulmonary metastases from hepatocellular carcinoma: a retrospective study

Purpose: To determine the effectiveness of ablation for pulmonary metastases (PM) from hepatocellular carcinoma (HCC).Methods: Between 2010 and 2017, the study analyzed 39 patients who had a median age of 59 years. Primary HCC was under control and the number of PM was less than 5 (median: 2), with a maximum diameter of ≤60 mm (median: 15 mm). The primary endpoints were overall survival (OS) and local tumor progression-free survival (LTPFS). Secondary endpoints included technique success (TS), complication and tumor response. TS referred to PM treated using the treatment protocol. Multivariate analysis using the Cox proportional hazard model was conducted on the potential risk factors (univariate: p < 0.5) to determine the independent factors (multivariate: p < 0.05).Results: The TS rate was 100%. Major complications included pneumothorax (n = 3) requiring chest tube placement and pleural effusion requiring drainage (n = 2). Complete ablation was achieved in 32/38 patients (valid percent: 84.2%) at 1 month after ablation. The 1-, 3- and 5-year OS rates were 79.8, 58 and 30.9%, respectively. The 1-, 3- and 5-year LTPFS rates were 60.7, 34.2 and 22.8%, respectively. The extent (unilateral vs. bilateral) of PM (hazard ratio (HR): 0.197, 95% confidence interval (CI): 0.043-0.890, p = 0.035) and the number (≤2 vs. >2) of PM (HR: 0.555, 95% CI: 0.311-0.991, p = 0.047) were found to be the independent risk factors for predicting OS.Conclusion: Percutaneous thermal ablation is a safe and effective treatment for PM from HCC.

Magnetic resonance imaging-guided microwave ablation for lung tumor: a case report

Thoracoscopic surgery is considered to be the best treatment option for pulmonary lesions. However, for patients with clinical stage IIIA, surgery is not always feasible, due to a lack of sufficient lung function. Microwave ablation (MWA) is an appropriate, minimally invasive treatment option for these patients. In this case study, we present our initial experience with MWA guided by magnetic resonance imaging (MRI), in a patient with a lesion located in the right lower lobe. The patient was successfully ablated and achieved a long progression-free period.

Efficacy and safety of radiofrequency ablation for lung cancers: A systematic review and meta-analysis

OBJECTIVE

To evaluate the efficacy and safety of radiofrequency ablation(RFA) for patients with lung cancers using meta-analysis.

METHODS AND MATERIALS

A literature search (PubMed, Embase, Web of science and China National Knowledge Infrastructure) was undertaken until August 2017 to identify sufficient studies evaluating the efficacy and safety of RFA. Pooled proportions of estimates were calculated by performing the random effect model, including technical success rate, recurrence rate, local tumor progression rate and complications.

RESULTS

A total of 25 eligible studies were collected, giving a sample size of 1989 patients with 3025 lung tumors. In the present series, the pooled technical success rate was 96%(95%CIs: 93%-100%). Further, we observed pooled recurrence rate of 35%(95%CIs: 12%-59%) following RFA. Additionally, the pooled rate of local tumor progression was 26%(95%CIs: 20%-32%). One hundred and ninety major complications of RFA were reported in 20 studies, giving a pooled proportion of 6% (95%CIs: 3%-8%) for major RFA complications. Pooled rate of minor complications was 27% (95%CIs:14%-41%).

CONCLUSION

In this meta-analysis, RFA was found to be a safe and efficient treatment for the patients with lung cancers. The efficacy and safety of RFA for lung cancer deserve future investigation in further well-designed randomized controlled trials.

Aspergillosis complicating a microwave ablation cavity

We present a case of a patient who following chemotherapy developed semi-invasive pulmonary aspergillosis and an aspergilloma in a lung cavity previously formed by microwave ablation (MWA). A 55-year-old woman presented with cough and shortness of breath after finishing three cycles of chemotherapy for a metastatic nerve sheath tumour. She had been treated by MWA for pulmonary metastases 2 years previously which resulted in a residual right apical lung cavity. Postchemotherapy imaging showed that this cavity had enlarged, developed a thicker wall and contained lobulated soft tissue with a crescent sign on coronal reformats. In addition, the patient's Aspergillus-specific IgG was markedly raised. Treatment with itraconazole improved the symptoms and reduced the cavity size and wall thickness. This case shows that persisting lung cavities after MWA are a potential site for semi-invasive aspergillosis and has implications for the timing of chemotherapy in patient with metastatic lung disease.

Pulmonary radiofrequency ablation in a district general hospital: is it a safe and effective treatment?

AIM

To analyse the technical success of ablation therapy and the incidence of complications in patients treated with pulmonary ablation and to assess factors affecting local disease control and patient survival in a subgroup with metastatic colorectal cancer.

MATERIALS AND METHODS

Technical success and complications in all patients undergoing lung ablation between June 2009 and July 2015 were recorded. Overall survival and local disease control in a subgroup with metastases from a colorectal primary were calculated. Factors influencing outcome were explored.

RESULTS

Two hundred and seven pulmonary ablations were performed in 86 patients at 156 attendances. Technical success was achieved in 207/207 (100%). Thirty and 90-day mortality was 0%. The major complication rate was 13/86 (15%). One hundred and one metastases were treated in 46 patients with a colorectal primary. This group had a mean ± standard error survival time of 53.58±3.47 months with a 1, 2, 3, 4, and 5-year survival rate of 97.4%, 91.3%, 81.5%, 59.8%, and 48%. There was no statistically significant difference in survival regarding time to development of metastatic disease, the total number of lesions ablated, the initial number of lesions ablated, the maximum size of lesion treated, or unilateral versus bilateral disease. Patients with extrapulmonary disease were found to have a shorter survival from the primary diagnosis. Seventy-eight (77.2%) of the 101 lesions were stable after first RFA. Local relapse was more likely when a metastasis was close to a large (>3 mm) vessel.

CONCLUSION

RFA is a safe and effective procedure that can be performed without on-site cardiothoracic support. Good outcomes depend upon careful patient selection. This study supports its use in oligometastatic disease.

Radiofrequency ablation in primary non-small cell lung cancer: What a radiologist needs to know

Lung cancer continues to be one of the leading causes of death worldwide. In advanced cases of lung cancer, a multimodality approach is often applied, however with poor local control rates. In early non-small cell lung cancer (NSCLC), surgery is the standard of care. Only 15-30% of patients are eligible for surgical resection. Improvements in imaging and treatment delivery systems have provided new tools to better target these tumors. Stereotactic body radiation therapy (SBRT) has evolved as the next best option. The role of radiofrequency ablation (RFA) is also growing. Currently, it is a third-line option in stage 1 NSCLC, when SBRT cannot be performed. More recent studies have demonstrated usefulness in recurrent tumors and some authors have also suggested combination of RFA with other modalities in larger tumors. Following the National Lung Screening Trial (NLST), screening by low-dose computed tomography (CT) has demonstrated high rates of early-stage lung cancer detection in high-risk populations. Hence, even considering the current role of RFA as a third-line option, in view of increasing numbers of occurrences detected, the number of potential RFA candidates may see a steep uptrend. In view of all this, it is imperative that interventional radiologists be familiar with the techniques of lung ablation. The aim of this article is to discuss the procedural technique of RFA in the lung and review the current evidence regarding RFA for NSCLC.

Microwave ablation of liver tumors: degree of tissue contraction as compared to RF ablation

PURPOSE

To compare the amount of tissue contraction after microwave (MW) versus radiofrequency (RF) ablation of liver tumors.

MATERIALS AND METHODS

Seventy-five hepatic tumors in 65 patients who underwent percutaneous MW or RF ablations were included in this retrospective study. All patients underwent MRI within 6 months before the ablation and 24 h after the procedure. Two blinded radiologists, by consensus, performed measurements on the corresponding series of pre and post-ablation MRI. Absolute and relative contraction of liver, tumor, and control were calculated and compared.

RESULTS

Thirty-one patients underwent MW ablations, and 44 patients underwent RF ablations. The absolute and relative contraction of the ablation zone were significantly greater with MW than RF ablation (p = 0.003 to <0.001). Thirty-two lesions were visible on both pre- and post-ablation MRI. MW ablation had significantly more tumor contraction as compared to RF ablation (p = 0.003 to 0.009). The control measurements demonstrated no significant difference in normal tissue variation between MW and RF groups.

CONCLUSIONS

MW ablation of hepatic tumors produced significantly more contraction of tumor and ablated hepatic tissue compared to RF ablation. Tissue contraction should be taken into account during pre-procedural planning and assessing treatment response by comparing pre- and post-ablation images.

Chinese expert consensus workshop report: Guidelines for thermal ablation of primary and metastatic lung tumors

Although surgical resection is the primary means of curing both primary and metastatic lung cancers, about 80% of lung cancers cannot be removed by surgery. As most patients with unresectable lung cancer receive only limited benefits from traditional radiotherapy and chemotherapy, many new local treatment methods have emerged, including local ablation therapy. The Minimally Invasive and Comprehensive Treatment of Lung Cancer Branch, Professional Committee of Minimally Invasive Treatment of Cancer of the Chinese Anti-Cancer Association has organized multidisciplinary experts to develop guidelines for this treatment modality. These guidelines aim at standardizing thermal ablation procedures and criteria for selecting treatment candidates and assessing outcomes; and for preventing and managing post-ablation complications.

Lung radiofrequency and microwave ablation: a review of indications, techniques and post-procedural imaging appearances

Lung ablation can be used to treat both primary and secondary thoracic malignancies. Evidence to support its use, particularly for metastases from colonic primary tumours, is now strong, with survival data in selected cases approaching that seen after surgery. Because of this, the use of ablative techniques (particularly thermal ablation) is growing and the Royal College of Radiologists predict that the number of patients who could benefit from such treatment may reach in excess of 5000 per year in the UK. Treatment is often limited to larger regional centres, and general radiologists often have limited awareness of the current indications and the techniques involved. Furthermore, radiologists without any prior experience are frequently expected to interpret post-treatment imaging, often performed in the context of acute complications, which have occurred after discharge. This review aims to provide an overview of the current indications for pulmonary ablation, together with the techniques involved and the range of post-procedural appearances.

CT volumetric assessment of pulmonary neoplasms after radiofrequency ablation: when to consider a second intervention?

PURPOSE

To determine the minimal follow-up time point to predict therapeutic response to radiofrequency (RF) ablation of lung tumors.

MATERIALS AND METHODS

A retrospective study design was approved by the institutional review board. From January 2008 to January 2010, 78 patients (46 men and 32 women; mean age, 58.9 y) underwent computed tomography (CT)-guided percutaneous RF ablation of pulmonary malignancies. A single RF multitined electrode was used to treat 100 index tumors, 6 primary lesions, and 94 metastatic lesions. CT volumetric measurements of ablated tumors were made before ablation and 24 hours, 3-6 weeks, 3 months, 6 months, 9 months, and 12 months after ablation. An unpaired t test and Spearman rank correlation coefficient were used to analyze the volumetric changes.

RESULTS

Complete successful ablation was achieved in 80% of index tumors. The mean time to detection of tumor residue or recurrence tumor residue or recurrence was 6.7 months after ablation. In successfully ablated lesions, the mean volume before ablation was 1.81 cm(3) (standard deviation [SD], 1.71); in failed ablation lesions, the mean volume before ablation was 2.58 cm(3) (SD, 2.8) (P = .42). The earliest statistically significant follow-up time point that showed a difference in the volumetric measurements of failed and successful ablations as well as the earliest significant correlation with the 12-month point was 3 months (P = .025, Spearman R = 0.72). Secondary tumor control after repeat ablation was statistically significant for lesions ablated at a 3-month interval (four out of five lesions) (P = .04).

CONCLUSIONS

CT volumetric assessment of ablated tumors revealed that 3 months was the earliest time point that may determine the response of a pulmonary ablation or repeat intervention.

Percutaneous strategies for the management of pulmonary parenchymal, chest wall, and pleural metastases

OBJECTIVE

The purposes of this article are to review the indications for and technical aspects of various percutaneous strategies available for the treatment of intrathoracic metastases involving the parenchyma, pleura, and chest wall and to describe the relative merits of one of these strategies over another to determine the best approach to use.

CONCLUSION

The thorax is a common site of metastatic disease with frequent involvement of the lungs, pleura, and osseous structures. A variety of interventional procedures and techniques are available for treatment and for palliative care of patients with this disease. Imaging-guided interventions include thermal ablation of metastatic disease of the lungs and pleura, catheter placement and sclerosis of malignant pleural effusions, and palliative pain management for osseous and soft-tissue metastases.

Imaging Features following Thermal Ablation of Lung Malignancies

Percutaneous image-guided thermal ablation is gaining attraction as an effective alternative to surgical resection for patients with primary and secondary malignancies of the lung. Currently, no standard follow-up imaging protocol has been established or uniformly accepted. The early identification of residual or recurrent tumor would in theory enable the practitioner to offer expeditious retreatment or alternative treatment. This review elaborates on the imaging findings following thermal ablation, both heat- and cold-based, of nonresectable pulmonary malignancies.

Lung cancer ablation: technologies and techniques

The incidence of lung cancers in 2012 is estimated to reach 226,160 new cases, with only a third of patients suitable surgical candidates. Tumor ablation has emerged as an important and efficacious treatment option for nonsurgical lung cancer patients. This localized minimally invasive therapy is best suited for small oligonodular lesions or favorably located metastatic tumors. Radiofrequency ablation has been in use for over a decade, and newer modalities including microwave ablation, cryoablation, and irreversible electroporation have emerged as additional treatment options for patients. Ablation therapies can offer patients and clinicians a repeatable and effective therapy for palliation and, in some cases, cure of thoracic malignancies. This article discusses the available technologies and techniques available for tumor ablation of thoracic malignancies including patient selection, basic aspects of procedure technique, imaging follow-up, treatment outcomes, and comparisons between various therapies.

Radiofrequency ablation as treatment for pulmonary metastasis of colorectal cancer

Radiofrequency ablation (RFA) causes focal coagulation necrosis in tissue. Its first clinical application was reported in 2000, and RFA has since been commonly used in both primary and metastatic lung cancer. The procedure is typically performed using computed tomography guidance, and the techniques for introducing the electrode to the tumor are simple and resemble those used in percutaneous lung biopsy. The most common complication is pneumothorax, which occurs in up to 50% of procedures; chest tube placement for pneumothorax is required in up to 25% of procedures. Other severe complications, such as pleural effusion requiring chest tube placement, infection, and nerve injury, are rare. The local efficacy depends on tumor size, and local progression after RFA is not rare, occurring in 10% or more of patients. The local progression rate is particularly high for tumors > 3 cm. Repeat RFA may be used to treat local progression. Short- to mid-term survival after RFA appears promising and is approximately 85%-95% at 1 year and 45%-55% at 3 years. Long-term survival data are sparse. Better survival may be expected for patients with small metastasis, low carcinoembryonic antigen levels, and/or no extrapulmonary metastasis. The notable advantages of RFA are that it is simple and minimally invasive; preserves pulmonary function; can be repeated; and is applicable regardless of previous treatments. Its most substantial limitation is limited local efficacy. Although surgery is still the method of choice for treatment with curative intent, the ultimate application of RFA may be to replace metastasectomy for small metastases. Randomized trials comparing RFA with surgery are needed.

Alternative to surgery in early stage NSCLC-interventional radiologic approaches

Interventional radiologists have a variety of techniques in their armamentarium to treat pulmonary tumors. While most therapies are targeted to metastasis or palliation, percutaneous thermal ablation represents a potential therapy for not only palliation, but to treat inoperable early stage disease. Although radiofrequency ablation (RFA) is the most studied of these ablative techniques, newer technologies of thermal ablation, such as microwave and cryoablation have emerged as additional options. In this article, we will review the three different thermal ablative modalities, including patient selection, technique, outcomes, complications, and imaging follow-up. A brief discussion of state of the art techniques such as irreversible electroporation (IRE) and catheter directed therapies will also be included.

Radiofrequency ablation of lung tumors: imaging features of the postablation zone

Radiofrequency ablation (RFA) is used to treat pulmonary malignancies. Although preliminary results are suggestive of a survival benefit, local progression rates are appreciable. Because a patient can undergo repeat treatment if recurrence is detected early, reliable post-RFA imaging follow-up is critical. The purpose of this article is to describe (a) an algorithm for post-RFA imaging surveillance; (b) the computed tomographic (CT) appearance, size, enhancement, and positron emission tomographic (PET) metabolic activity of the ablation zone; and (c) CT, PET, and dual-modality imaging with PET and CT (PET/CT) features suggestive of partial ablation or tumor recurrence and progression. CT is routinely used for post-RFA follow-up. PET and PET/CT have emerged as auxiliary follow-up techniques. CT with nodule densitometry may be used to supplement standard CT. Post-RFA follow-up was divided into three phases: early (immediately after to 1 week after RFA), intermediate (>1 week to 2 months), and late (>2 months). CT and PET imaging features suggestive of residual or recurrent disease include (a) increasing contrast material uptake in the ablation zone (>180 seconds on dynamic images), nodular enhancement measuring more than 10 mm, any central enhancement greater than 15 HU, and enhancement greater than baseline anytime after ablation; (b) growth of the RFA zone after 3 months (compared with baseline) and definitely after 6 months, peripheral nodular growth and change from ground-glass opacity to solid opacity, regional or distant lymph node enlargement, and new intrathoracic or extrathoracic disease; and (c) increased metabolic activity beyond 2 months, residual activity centrally or at the ablated tumor, and development of nodular activity.

Irreversible electroporation of lung neoplasm: a case series

Background

Percutaneous irreversible electroporation (IRE) of lung tumors is a new minimally invasive technique which has recently been used in the treatment of soft tissue tumors.

Case Reports

The case histories are presented of two patients with unresectable malignancies in the lung, who underwent irreversible electroporation as a treatment attempt. The procedure was performed under CT guidance and was uneventful.

Conclusions

At follow up 6 months later, the tumors both appeared to have recurred. To our knowledge, no similar cases have previously been reported in the literature.

Complications of radiofrequency ablation of hepatic, pulmonary, and renal neoplasms

Percutaneous thermal ablation has emerged as a viable technique for treatment of numerous solid organ malignancies. As the number of these procedures increases, so do the complications that are seen. Most common complications are generally related to bleeding from the target organ during or after the procedure and from thermal injury to adjacent structures. The nature of these injuries depends on the particular organ being treated, therefore it it best to categorize them this way. We will review the more common complications seen following the ablation of tumors in the liver, kidney, and lung, discuss the clinical presentation associated with each, and suggest precautions to help avoid them in the future. Understanding the potential risks associated with this procedure is critical for treatment planning and fundamental for performing these procedures safely.

Imaging follow-up of RF ablation of lung tumours

Imaging is important in the decision-making process of how to treat a lung tumour, which ideally should be a multi-disciplinary team decision. Imaging is important during radiofrequency ablation (RFA) treatment with regard to optimal placement of the electrode, the immediate post-treatment criteria and very early detection of complications of the procedure. Imaging is very important in the treatment follow-up. In lung RFA, as in many other interventional procedures, the traditional morphological imaging techniques to evaluate treatment response have difficulties and functional imaging techniques may potentially be more useful. However, larger studies showing this impact have not yet been performed.

Radiofrequency ablation of concomitant and recurrent pulmonary metastases after surgery for colorectal liver metastases

BACKGROUND

To evaluate our experience of radiofrequency ablation (RFA) of pulmonary metastases in patients with resected colorectal liver metastases who had concomitant or recurrent pulmonary metastases.

METHODS

Clinical and treatment variables of patients undergoing RFA were collected, and their association with survival was examined. Survival analysis was performed by the Kaplan-Meier method.

RESULTS

RFA was performed as concomitant sequential treatment of extrahepatic pulmonary metastases after hepatectomy in 19 patients (30%) and as salvage treatment for pulmonary recurrences after hepatectomy in 45 patients (70%). Patients undergoing sequential treatment had a median survival of 31 (95% confidence interval [CI] 21.8-40.6) months compared to 59 (95% CI 35.0-82.0) months in the salvage treatment group (P = 0.142). The disease-free survival (DFS) was 9 (95% CI 1.0-18.8) months in the sequential treatment group and 16 (95% CI 8.1-23.1) months in the salvage treatment group (P = 0.023). Liver metastases occurring within 12 months of the primary tumor negatively influenced overall survival (OS) and DFS in the sequential treatment group (P = 0.003 and P = 0.091). Poorly differentiated tumor (P = 0.001) was associated with a poorer OS, and prehepatectomy carcinoembryonic antigen > 200 ng/ml (P = 0.017) and bilateral pulmonary metastases (P = 0.030) were associated with a shorter DFS in the salvage treatment group.

CONCLUSIONS

The DFS and OS of patients undergoing sequential RFA of extrahepatic pulmonary metastases after hepatectomy appeared shorter when compared to patients who underwent RFA as salvage treatment for pulmonary recurrences after hepatectomy. It nonetheless remains better than the historical results of chemotherapy alone and thus supports the use of RFA as an ablative technology to achieve tumor control.

Therapeutic response to radiofrequency ablation of neoplastic lesions: FDG PET/CT findings

Ablation of neoplastic lesions by using radiofrequency energy is gaining popularity in clinical practice because of the minimally invasive nature of radiofrequency ablation (RFA). Primary and secondary tumors of the liver and lung are treated with RFA when surgery is precluded because of comorbidity. Benign bone tumors are also treated with RFA to relieve pain and prevent further tumor growth. Differentiation between postablation tissue changes and residual disease is difficult with morphologic imaging modalities such as ultrasonography, computed tomography (CT), and magnetic resonance (MR) imaging, thus limiting the use of these modalities to detection of residual disease early after RFA. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is a functional imaging modality that can be used to study the effects and efficacy of RFA. Lesions that show increased FDG uptake at PET become completely photopenic immediately after RFA, a finding that is suggestive of the completeness of ablation. Focal areas of increased FDG uptake within the ablated zone are suggestive of residual disease. Reactive tissue changes such as inflammation are depicted in the periphery of the ablated lesion and show a uniform low-grade FDG uptake, which can be differentiated from the focal, nodular intense uptake in areas of residual disease. Use of combined FDG PET/CT to detect residual disease early after RFA allows ablation to be repeated, if necessary, to obtain the maximum therapeutic benefit. Note that FDG uptake in the complications sometimes associated with RFA can be a cause of potential false-positive PET results.

Evaluation of treatment response after nonoperative therapy for early-stage non-small cell lung carcinoma

Nonsurgical management of early primary lung cancer has grown tremendously in recent years, and today, available options extend far beyond that of conventional radiation therapy (CRT) to include minimally invasive image-guided delivery of thermal energies, specifically radiofrequency ablation, microwave ablation, and cryoablation, and more conformal stereotactic body radiation therapy. Because the tumor is never resected with these nonoperative interventions, histopathological evaluation of tumor margins for the presence of residual tumor is impossible, and as such, tumor response after each of these therapies is largely based on imaging. To date, computerized tomography and computerized tomography-positron emission tomography remain the most readily available modalities for assessment of therapeutic efficacy, and to this end as detailed within this article, strict imaging survey and familiarity with the expected imaging characteristics of the treated tumor will aid in recognition of unexpected findings, specifically those of incomplete therapy and/or tumor recurrence.

Imaging in interventional oncology

Medical imaging in interventional oncology is used differently than in diagnostic radiology and prioritizes different imaging features. Whereas diagnostic imaging prioritizes the highest-quality imaging, interventional imaging prioritizes real-time imaging with lower radiation dose in addition to high-quality imaging. In general, medical imaging plays five key roles in image-guided therapy, and interventional oncology, in particular. These roles are (a) preprocedure planning, (b) intraprocedural targeting, (c) intraprocedural monitoring, (d) intraprocedural control, and (e) postprocedure assessment. Although many of these roles are still relatively basic in interventional oncology, as research and development in medical imaging focuses on interventional needs, it is likely that the role of medical imaging in intervention will become even more integral and more widely applied. In this review, the current status of medical imaging for intervention in oncology will be described and directions for future development will be examined.

The efficacy of bipolar and multipolar radiofrequency ablation of lung neoplasms - results of an ablate and resect study

OBJECTIVE

Radiofrequency ablation (RFA) has obtained increasing attention as an interventional approach for the local treatment of primary and secondary lung neoplasms. The local effect of the procedure is usually controlled by radiologic means. The objectives of this 'ablate and resect' study were to investigate the efficacy of bipolar and multipolar RFA by histologic evaluation and to compare the two techniques.

METHODS

In a total of 32 subjects with histologically proven non-small-cell lung cancer or pulmonary metastases from an extrathoracic primary tumor, bipolar, or multipolar RFA was performed during open thoracotomy. Curative resection (lobectomy or wedge resection including mediastinal lymph node dissection) was performed subsequently. The extent of cell death and early histologic findings following RFA were determined by histology and immunohistochemistry (nicotinamide adenine dinucleotide (NADH) and monoclonal anti-mitochondrial antibodies MAB 1273).

RESULTS

Intra-operative bipolar and multipolar RFA is a safe procedure, and there was no bleeding or thermal damage of the lung tissue. Routine histologic staining could not identify tumor cell death. However, immunohistochemistry was able to verify cell death in the ablated tumor tissue. Complete tumor cell necrosis was determined in 12 tumors (37.5%); and scattered vital tumor tissue was detected in 16 tumors (50%). Incomplete ablation with a ratio of >20% vital tumor tissue was found in four tumors (12.5%), particularly surrounding vascular structures within the tumor tissue or in marginal zones of the tumor tissue. The local efficacy of bipolar and multipolar RFA was comparable, and incomplete ablations were found only in adenocarcinoma.

CONCLUSIONS

Bipolar and multipolar RFA in an open thoracotomy setting is a technically feasible and safe procedure. Early immunohistochemical findings after RFA showed complete tumor cell necrosis in 38% of cases. The high rate of viable tumor cells remaining after ablation casts doubt on RFA as a curative concept. This approach should be reserved for palliative indications. Patients fulfilling the criteria for curative resection should not be denied surgery.

Tissue contraction caused by radiofrequency and microwave ablation: a laboratory study in liver and lung

PURPOSE

To determine the amount of tissue contraction during radiofrequency (RF) and microwave ablation.

MATERIALS AND METHODS

Markers were inserted into explanted bovine liver and lung 10 mm (inner), 20 mm (middle; not used in lung), and 30 mm (peripheral) diametrically around an ablation applicator. Aside from unablated controls, RF and microwave ablations 25-30 mm in diameter were then created and sectioned to measure the distance between markers (n = 12, liver RF; n = 8, other). Total contraction was calculated by subtracting postablation measurements from controls at each position. Relative contraction was calculated by subtracting the nearest more central measurement. Sample water content was measured to determine the relationship between dehydration and relative contraction. A mixed-effects model tested for differences in diameters, total and relative contraction, and water content with energy, tissue, and marker position as independent variables.

RESULTS

Total contractions at the inner, middle, and peripheral positions in liver were 2.9 mm (31%), 4.8 mm (24%), and 4.5 mm (15%) for RF and 3.6 mm (38%), 6.6 mm (33%), and 9.0 mm (30%) for microwave, respectively. Significantly more contraction was noted in lung (P < .001): 5.1 mm (55%) and 14.2 mm (49%) for RF and 4.8 mm (52%) and 13.7 mm (47%) for microwave at the inner and peripheral positions, respectively. Microwaves produced more contraction than RF in liver (P < .05) but not in lung. A positive correlation between dehydration and relative contraction was observed in all cases.

CONCLUSIONS

Ablation-induced tissue contraction is substantial and influenced by dehydration. Contraction should be considered when testing devices and computer models or comparing pre- and postablation images.