Percutaneous radiofrequency ablation of lung neoplasms: initial therapeutic response

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.

Update on Image-Guided Thermal Lung Ablation: Society Guidelines, Therapeutic Alternatives, and Postablation Imaging Findings

Percutaneous image-guided thermal ablation (IGTA) has been endorsed by multiple societies as a safe and effective lung-preserving treatment for primary lung cancer and metastases involving the lung and chest wall. This article reviews the role of IGTA in the care continuum of patients with thoracic neoplasms and discusses strategies to identify the optimal local therapy considering patient and tumor characteristics. The advantages and disadvantages of percutaneous thermal ablation compared to surgical resection and stereotactic body radiotherapy are summarized. Principles of radiofrequency ablation, microwave ablation, and cryoablation, as well as the emerging use of transbronchial thermal ablation, are described. Specific considerations are presented regarding the role of thermal ablation for early-stage non-small cell lung cancer (NSCLC), multifocal primary NSCLC, pulmonary metastases, salvage of recurrent NSCLC after surgery or radiation, and pain palliation for tumors involving the chest wall. Recent changes to professional society guidelines regarding the role of thermal ablation in the lung, including for treatment of oligometastatic disease, are highlighted. Finally, recommendations are provided for imaging follow-up after thermal ablation of lung tumors, accompanied by examples of expected postoperative findings and patterns of disease recurrence.

Technical and safety performance of CT-guided percutaneous microwave ablation for lung tumors: an ablate and resect study

BACKGROUND

Percutaneous image-guided thermal ablation has an increasing role in the treatment of primary and metastatic lung tumors. Achieving acceptable clinical outcomes requires better tools for pre-procedure prediction of ablation zone size and shape.

METHODS

This was a prospective, non-randomized, single-arm, multicenter study conducted by Medtronic (ClinicalTrials.gov ID: NCT02323854). Subjects scheduled for resection of metastatic or primary lung nodules underwent preoperative percutaneous microwave ablation. Ablation zones as measured via CT imaging following ablation immediately and before resection surgically versus predicted ablation zones as prescribed by the investigational system software were compared. This CT scan occurred after the ablation was finished but the antenna still in position. Time (minutes) from antenna placement to removal was 23.7±13.1 (n=14); median: 21.0 (range, 6.0 to 48.0). The definition of the secondary endpoint of complete ablation was 100% non-viable tumor cells based on nicotinamide adenine dinucleotide hydrogen (NADH) staining. Safety endpoints were type, incidence, and severity of adverse events.

RESULTS

Fifteen patients (mean age 58.9 years; 67% male; 33% female) were enrolled in the study, 33.3% (5/15) with previous thoracic surgery, 73% (11/15) with metastasis, and 27% (4/15) with primary lung tumors. All underwent percutaneous microwave ablation followed by surgical resection the same day. Complete ablation was detected in 54.4% (6/11), incomplete ablation in 36.4% (4/11), and delayed necrosis in 9.1% (1/11). There were no device-related adverse events. Ablation zone volume was overestimated in all patients.

CONCLUSIONS

Histological complete ablation was observed in 55% of subjects. CT scanning less than an hour after ablation and tissue shrinkage may account for the smaller zone of ablation observed compared to predicted by the investigational system software.

Imaging following thermal ablation of early lung cancers: expected post-treatment findings and tumour recurrence

Thermal ablation is a minimally invasive technique that is growing in acceptance and popularity in the management of early lung cancers. Although curative resection remains the optimal treatment strategy for stage I pulmonary malignancies, percutaneous ablative treatments may also be considered for selected patients. These techniques can additionally be used in the treatment of oligometastatic disease. Thermal ablation of early lung tumours can be achieved using several different techniques. For example, microwave ablation (MWA) and radiofrequency ablation (RFA) utilise extreme heat, whereas cryoablation uses extremely cold temperatures to cause necrosis and ultimately cell death. Typically, post-ablation imaging studies are performed within the first 1-3 months with subsequent imaging performed at regular intervals to ensure treatment response and to evaluate for signs of recurrent disease. Surveillance imaging is usually undertaken with computed tomography (CT) and integrated positron-emission tomography (PET)/CT. Typical imaging findings are usually seen on CT and PET/CT following thermal ablation of lung tumours, and it is vital that radiologists are familiar with these appearances. In addition, radiologists should be aware of the imaging findings that indicate local recurrence following ablation. The objective of this review is to provide an overview of the expected post-treatment findings on CT and PET/CT following thermal ablation of early primary lung malignancies, as well as describing the imaging appearances of local recurrence.

Society of Interventional Radiology Quality Improvement Standards on Percutaneous Ablation of Non-Small Cell Lung Cancer and Metastatic Disease to the Lungs

PURPOSE

To provide guidance on quality improvement thresholds for outcomes and complications of image-guided thermal ablation for the treatment of early stage non-small cell lung cancer, recurrent lung cancer, and metastatic disease.

MATERIALS AND METHODS

A multidisciplinary writing group conducted a comprehensive literature search to identify studies on the topic of interest. Data were extracted from relevant studies and thresholds were derived from a calculation of 2 standard deviations from the weighted mean of each outcome. A modified Delphi technique was used to achieve consensus agreement on the thresholds.

RESULTS

Data from 29 studies, including systematic reviews and meta-analyses, retrospective cohort studies, and single-arm trials were extracted for calculation of the thresholds. The expert writing group agreed on thresholds for local control, overall survival and adverse events associated with image-guided thermal ablation.

CONCLUSION

SIR recommends utilizing the indicator thresholds to review and assess the efficacy of ongoing quality improvement programs. When performance falls above or below specific thresholds, consideration of a review of policies and procedures to assess for potential causes, and to implement changes in practices, may be warranted.

Non-surgical Treatments for Lung Metastases in Patients with Soft Tissue Sarcoma: Stereotactic Body Radiation Therapy (SBRT) and Radiofrequency Ablation (RFA)

BACKGROUND

Radio-frequency ablation (RFA) and Stereotactic Body Radiation Therapy (SBRT) are two emerging therapies for lung metastases.

INTRODUCTION

Aliterature review was performed to evaluate the outcomes and complications of these procedures in patients with lung metastases from soft tissue sarcoma (STS).

METHODS

After selection, seven studies were included for each treatment encompassing a total of 424 patients: 218 in the SBRT group and 206 in the RFA group.

RESULTS

The mean age ranged from 47.9 to 64 years in the SBRT group and from 48 to 62.7 years in the RFA group. The most common histologic subtype was, in both groups, leiomyosarcoma. In the SBRT group, median overall survival ranged from 25.2 to 69 months and median disease- free interval was from 8.4 to 45 months. Two out of seven studies reported G3 and one G3 toxicity, respectively. In RFA patients, overall survival ranged from 15 to 50 months. The most frequent complication was pneumothorax. Local control showed a high percentage for both procedures.

CONCLUSION

SBRT is recommended in patients unsuitable to surgery, in synchronous bilateral pulmonary metastases, in case of deep lesions and patients receiving high-risk systemic therapies. RFA is indicated in case of a long disease-free interval, in oligometastatic disease, when only the lung is involved, in small size lesions far from large vessels. Further large randomized studies are necessary to establish whether these treatments may also represent a reliable alternative to surgery.

18F-FDG PET/CT performed immediately after percutaneous ablation to evaluate outcomes of the procedure: preliminary results

Objective

To determine whether ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography performed immediately after percutaneous ablation (_iPA¹⁸F-FDG PET/CT) is useful in evaluating the outcomes of the procedure.

Materials and Methods

This was a retrospective study of 20 patients (13 males, 7 females; mean age, 65.8 ± 12.1 years) submitted to percutaneous ablation of metastases. All of the lesions treated had shown focal uptake on a ¹⁸F-FDG PET/CT scan obtained at baseline. The primary tumors were mainly colorectal cancer (in 45%) or lung cancer (in 40%). _iPA¹⁸F-FDG PET/CT was performed to identify any residual viable tumor cells. The treatment was considered a success (no viable tumor cells present) if no uptake of ¹⁸F-FDG was noted on the _iPA¹⁸F-FDG PET/CT scan.

Results

Twenty-six lesions were submitted to percutaneous ablation with either cryoablation (n = 7) or radiofrequency ablation (n = 19). The mean lesion diameter was 2.52 ± 1.49 cm. For the detection of viable tumor cells, _iPA¹⁸F-FDG PET/CT had a sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 66.7%, 95%, 88.5%, 80%, and 90.5%, respectively. There was a significant correlation between the _iPA¹⁸F-FDG PET/CT findings and the results of the follow-up studies (kappa = 0.66; p < 0.01).

Conclusion

_iPA¹⁸F-FDG PET/CT studies appear to constitute a useful means of evaluating the outcomes of percutaneous ablation. By detecting residual viable tumor cells, this strategy might allow early re-intervention, thus reducing morbidity. Studies involving larger numbers of patients are needed in order to confirm our findings.

Microwave Ablation in the Management of Colorectal Cancer Pulmonary Metastases

PURPOSE

To review outcomes following microwave ablation (MWA) of colorectal cancer pulmonary metastases and assess predictors of oncologic outcomes.

METHODS

Technical success, primary and secondary technique efficacy rates were evaluated for 50 patients with 90 colorectal cancer pulmonary metastases at immediate, 4-8 weeks post-MWA and subsequent follow-up CT and/or ¹⁸F-FDG PET/CT. Local tumor progression (LTP) rate, LTP-free survival (LTPFS), cancer-specific and overall survivals were assessed. Complications were recorded according to SIR classification.

RESULTS

Median follow-up was 25.6 months. Median tumor size was 1 cm (0.3-3.2 cm). Technical success, primary and secondary technique efficacy rates were 99, 90 and 92%, respectively. LTP rate was 10%. One-, 2- and 3-year LTPFS were: 93, 86 and 86%, respectively, with median LTPFS not reached. Median overall survival was 58.6 months, and median cancer-specific survival (CSS) was not reached. One-, 2- and 3-year overall and CSS were 94% and 98, 82 and 90%, 61 and 70%, respectively. On univariate analysis, minimal ablation margin (p < 0.001) and tumor size (p = 0.001) predicted LTPFS, with no LTP for minimal margin ≥ 5 mm and/or tumor size < 1 cm. Pleural-based metastases were associated with increased LTP risk (p = 0.002, SHR = 7.7). Pre-MWA CEA level > 10 ng/ml (p = 0.046) and ≥ 3 prior chemotherapy lines predicted decreased CSS (p = 0.02). There was no 90-day death. Major complications rate was 13%.

CONCLUSIONS

MWA with minimal ablation margin ≥ 5 mm is essential for local control of colorectal cancer pulmonary metastases. Pleural-based metastases and larger tumor size were associated with higher risk of LTP. CEA level and pre-MWA chemotherapy impacted CSS.

Oncological outcome after lung metastasis in patients presenting with localized chondrosarcoma at extremities: Tokai Musculoskeletal Oncology Consortium study

The oncological outcome after lung metastasis in patients with chondrosarcoma of the extremities has not been reported. Between June 2000 and June 2013, 179 patients with chondrosarcoma in the extremities were treated at eleven hospitals. Twenty consecutive patients (11.2%) developed lung metastases after initial treatment of primary chondrosarcoma in the extremities. We investigated the oncological outcome of 20 chondrosarcoma patients with lung metastasis. There were 14 males and six females with a mean age of 49 years. The mean duration between primary surgery and appearance of lung metastases was 34 months. The mean follow-up period was 48 months. We excluded patients with lung metastasis at the time of presentation from this study. At the final follow-up, four of 20 patients had no evidence of disease, four were alive with disease, and twelve had died of disease. The 3- and 5-year survival rates after lung metastasis were 51.5% and 45.7%, respectively. Tumor grade, extrapulmonary metastasis, and treatment for lung metastases including metastasectomy and radiofrequency ablation were identified by univariate analysis to be significant prognostic factors for oncological analysis. In conclusion, this study evaluated the oncological outcome in patients with chondrosarcoma of the extremities with lung metastasis. Although a large-scale study might be required to confirm the results of this study, we suggest that metastasectomy and/or radiofrequency ablation should be considered to improve postmetastatic survival.

Clinical experiences with microwave thermal ablation of lung malignancies

Approximately 30% of early stage lung cancer patients are not surgical candidates due to medical co-morbidities, poor cardiopulmonary function and advanced age. These patients are traditionally offered chemotherapy and radiation, which have shown relatively modest improvements in mortality. For over a decade, percutaneous image-guided ablation has emerged as a safe, cost-effective, minimally invasive treatment alternative for patients who would otherwise not qualify for surgery. Although radiofrequency ablation (RFA) is currently the most extensively studied and widely utilised technique in the treatment of lung malignancies, there is a growing body of evidence that microwave ablation (MWA) has several unique benefits over RFA and cryoablation in the lung. This article reviews our institution's clinical experiences in the treatment of lung malignancies with MWA including patient selection, procedural technique, imaging follow-up, treatment outcomes and comparison of ablation techniques.

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.

Diagnostic Ability of Percutaneous Needle Biopsy Immediately After Radiofrequency Ablation for Malignant Lung Tumors: An Initial Experience

PURPOSE

To evaluate the safety and diagnostic ability of percutaneous needle biopsy performed immediately after lung radiofrequency ablation (RFA).

MATERIALS AND METHODS

From May 2013 to April 2014, percutaneous needle biopsy was performed immediately after RFA for 3 patients (2 men and 1 woman, aged 57-76 years) who had lung tumors measuring 1.3-2.6 cm in diameter. All patients had prior history of malignancy, and all tumors were radiologically diagnosed as malignant. Obtained specimens were pathologically classified using standard hematoxylin and eosin staining.

RESULTS

We completed three planned sessions of RFA followed by percutaneous needle biopsy, all of which obtained tumor tissue that could be pathologically diagnosed. Two tumors were metastatic from renal clear cell carcinoma and rectal adenocarcinoma, respectively; one tumor was primary lung adenocarcinoma. There was no death or major complication related to the procedures. Although pneumothorax occurred in two patients, these resolved without the need for aspiration or chest tube placement. Tumor seeding was not observed, but 21 months after the procedure, one case developed local tumor progression that was treated by additional RFA.

CONCLUSION

Pathologic diagnosis was possible by needle biopsy immediately after RFA for lung tumors. This technique may reduce the risks and efforts of performing biopsy and RFA on separate occasions.

Cone beam computed tomography images fusion in predicting lung ablation volumes: a feasibility study

BACKGROUND

Recently different software with the ability to plan ablation volumes have been developed in order to minimize the number of attempts of positioning electrodes and to improve a safe overall tumor coverage.

PURPOSE

To assess the feasibility of three-dimensional cone beam computed tomography (3D CBCT) fusion imaging with "virtual probe" positioning, to predict ablation volume in lung tumors treated percutaneously.

MATERIAL AND METHODS

Pre-procedural computed tomography contrast-enhanced scans (CECT) were merged with a CBCT volume obtained to plan the ablation. An offline tumor segmentation was performed to determine the number of antennae and their positioning within the tumor. The volume of ablation obtained, evaluated on CECT performed after 1 month, was compared with the pre-procedural predicted one. Feasibility was assessed on the basis of accuracy evaluation (visual evaluation [VE] and quantitative evaluation [QE]), technical success (TS), and technical effectiveness (TE).

RESULTS

Seven of the patients with lung tumor treated by percutaneous thermal ablation were selected and treated on the basis of the 3D CBCT fusion imaging. In all cases the volume of ablation predicted was in accordance with that obtained. The difference in volume between predicted ablation volumes and obtained ones on CECT at 1 month was 1.8 cm(3) (SD ± 2, min. 0.4, max. 0.9) for MW and 0.9 cm(3) (SD ± 1.1, min. 0.1, max. 0.7) for RF.

CONCLUSION

Use of pre-procedural 3D CBCT fusion imaging could be useful to define expected ablation volumes. However, more patients are needed to ensure stronger evidence.

Surgical management and minimally invasive approaches for the treatment of metastatic sarcoma

Soft tissue sarcomas describe a very heterogeneous group of soft tissue tumors mainly arising in the lower extremities. If diagnosed at an early stage and a complete resection of the primary tumor is achieved, the patients' prognosis is excellent. However, metastatic tumor spread is common with only limited treatment possibilities. Despite an improved insight into tumor biology of sarcomas, no notable improvement has been gained in the last 20 years regarding prognosis of patients. Metastatic lung disease has long been the preserve of systemic treatments, local treatments being considered in a purely palliative intention. Several studies have objectified benefit to the local treatment of metastases, especially in an oligometastatic state. The development of techniques for stereotactic radiotherapy on the one hand and the refusal or contraindication for surgery on the other hand inaugurated studies in this direction. Besides surgery and radiotherapy, other local modalities have been investigated in the last few years such as thermal therapy (radiofrequency and laser ablation) or combined modalities (isolated limb perfusion and deep-wave hyperthermia plus chemotherapy) to help patients with metastatic soft tissue sarcoma. Minimally invasive, image-guided therapies such as thermal ablation should be considered particularly in patients who are not suitable surgical candidates or may have exhausted all other viable surgical options. Some of these techniques will be reviewed in this article, and their value for the patients will be evaluated in the light of indication from tumor biology and technical feasibility. These highly selected and specific procedures should only be performed after decision making in an interdisciplinary sarcoma-board.

Comparative Effects of Dexmedetomidine and Propofol on US-Guided Radiofrequency Ablation of Hepatic Neoplasm Under Monitored Anesthesia Care: A Randomized Controlled Study

Percutaneous radiofrequency ablation (RFA) is a useful and safe procedure for treating hepatic neoplasm. However, liver RFA causes severe pain, which thereby increases the demand for monitored anesthesia care (MAC). Here, we compared the efficacy and safety of propofol and dexmedetomidine, which are commonly administered during MAC when performing RFA to assess hepatic neoplasm.In this randomized controlled trial, 40 patients were randomly allocated to 2 groups for elective RFA. Patients received either dexmedetomidine (group D) or propofol (group P). Both groups received the continuous infusion of remifentanil for pain control. The primary outcomes were opioid consumption and differences in partial pressure of arterial carbon dioxide (PaCO2) between pre- and postprocedure RFA. In addition, hemodynamic parameters, patient satisfaction, and interventional radiologist satisfaction were determined.There were significant differences in opioid consumption (50.1 ± 16.8 ng/kg/min [group D] vs 71.2 ± 18.7 ng/kg/min [group P]; P = 0.001) and delta PaCO2 (10.4 ± 6.4 mm Hg vs 17.2 ± 9.2 mm Hg, respectively; P = 0.016). Moreover, respiratory rates were significantly different between groups during RFA (P < 0.001). However, blood pressure and heart rate did not significantly change during RFA. Neither patient nor interventional radiologist satisfaction was significantly different between groups.Dexmedetomidine provides better respiratory stability and reduces opioid consumption in comparison with propofol when administered under MAC when performing RFA for hepatic neoplasm.

Utilization of laser interstitial thermotherapy guided by real-time thermal MRI as an alternative to separation surgery in the management of spinal metastasis

OBJECT

High-grade malignant spinal cord compression is commonly managed with a combination of surgery aimed at removing the epidural tumor, followed by spinal stereotactic radiosurgery (SSRS) aimed at local tumor control. The authors here introduce the use of spinal laser interstitial thermotherapy (SLITT) as an alternative to surgery prior to SSRS.

METHODS

Patients with a high degree of epidural malignant compression due to radioresistant tumors were selected for study. Visual analog scale (VAS) scores for pain and quality of life were obtained before and within 30 and 60 days after treatment. A laser probe was percutaneously placed in the epidural space. Real-time thermal MRI was used to monitor tissue damage in the region of interest. All patients received postoperative SSRS. The maximum thickness of the epidural tumor was measured, and the degree of epidural spinal cord compression (ESCC) was scored in pre- and postprocedure MRI.

RESULTS

In the 11 patients eligible for study, the mean VAS score for pain decreased from 6.18 in the preoperative period to 4.27 within 30 days and 2.8 within 60 days after the procedure. A similar VAS interrogating the percentage of quality of life demonstrated improvement from 60% preoperatively to 70% within both 30 and 60 days after treatment. Imaging follow-up 2 months after the procedure demonstrated a significant reduction in the mean thickness of the epidural tumor from 8.82 mm (95% CI 7.38-10.25) before treatment to 6.36 mm (95% CI 4.65-8.07) after SLITT and SSRS (p = 0.0001). The median preoperative ESCC Grade 2 was scored as 4, which was significantly higher than the score of 2 for Grade 1b (p = 0.04) on imaging follow-up 2 months after the procedure.

CONCLUTIONS

The authors present the first report on an innovative minimally invasive alternative to surgery in the management of spinal metastasis. In their early experience, SLITT has provided local control with low morbidity and improvement in both pain and the quality of life of patients.

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.

A phase II study of radiofrequency ablation therapy for thoracic malignancies with evaluation by FDG-PET

PURPOSE

Computed tomography (CT)-guided radiofrequency ablation (RFA) is safe and effective for patients with unresectable primary, recurrent, or metastatic thoracic malignancies. Several studies have shown the benefit of employing 18-fluoro-deoxyglucose positron-emission tomography (FDG-PET) to follow thoracic malignancies treated with RFA. In this prospective study, we show the safety and therapeutic efficacy of RFA and the utility of FDG-PET as tool for early detection of local recurrence.

METHODS

Twenty patients were enrolled in this study, and 24 lesions were ablated. Seven lesions were primary lung cancer, and 17 lesions were recurrent tumors or metastases from extrathoracic sites. Tumor size was in the range of 0.4-3.3 cm in diameter (mean: 1.5 cm). CT and FDG-PET scans were scheduled 7-14 days and 3-6 months after RFA treatment.

RESULTS

There were 17 adverse events (70.8 %) in 24 ablations included 13 pneumothoraces, two cases of chest pain, and two episodes of fever. With a median follow-up of 35.9 months (range 1-62 months), the overall 2-year survival rate was 84.2 %. Local recurrence occurred at four sites (2-year local control rate was 74.3 %). The FDG-PET results 7-14 days after RFA did not predict recurrence, whereas positive findings 3-6 months after RFA significantly correlated with local recurrence (p = 0.0016).

CONCLUSIONS

We confirmed the effectiveness of RFA for unresectable primary and secondary thoracic malignancies. FDG-PET analysis 3-6 months after ablation is a useful tool to assess local control.

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.

The Role of PET Imaging Before, During, and After Percutaneous Hepatic and Pulmonary Tumor Ablation

The combination of anatomic and metabolic information provided by positron emission tomography (PET)/computed tomography makes it an important imaging modality to be obtained in conjunction with percutaneous ablation of primary and secondary malignancies of the lungs and liver. Advantages include more accurate preprocedural staging to determine appropriate treatment options, intraprocedural guidance to target difficult-to-see lesions, and postprocedural detection of residual or recurrent disease. Future applications of PET include strategies for intraprocedural guidance with real-time determination of incompletely ablated tumor, and combined PET/magnetic resonance imaging before, during, and after ablation for greater sensitivity to detect disease.

Bipolar radiofrequency ablation of spinal tumors: predictability, safety and outcome

BACKGROUND

Bone metastases are often the cause of tumor-associated pain and reduction of quality of life. For patients that cannot be treated by surgery, a local minimally invasive therapy such as radiofrequency ablation can be a useful option. In cases in which tumorous masses are adjacent to vulnerable structures, the monopolar radiofrequency can cause severe neuronal damage because of the unpredictability of current flow.

PURPOSE

The aim of this study is to show that the bipolar radiofrequency ablation provides an opportunity to safely treat such spinal lesions because of precise predictability of the emerging ablation zone.

STUDY DESIGN

Prospective cohort study of 36 patients undergoing treatment at a single institution.

PATIENT SAMPLE

Thirty-six patients in advanced tumor stage with primary or secondary tumor involvement of spine undergoing radiofrequency ablation.

OUTCOME MEASURES

Prediction of emerging ablation zone. Clinical outcome of treated patients.

METHODS

X-ray-controlled treatment of 39 lesions by bipolar radiofrequency ablation. Magnetic resonance imaging was performed pre- and postinterventionally. Patients were observed clinically during their postinterventional stay.

RESULTS

The extent of the ablation zones was predictable to the millimeter because it did not cross the peri-interventional planned dorsal and ventral boundaries in any case. No complications were observed.

CONCLUSIONS

Ablation of tumorous masses adjacent to vulnerable structures is feasible and predictable by using the bipolar radiofrequency ablation. Damage of neuronal structures can be avoided through precise prediction of the ablation area.

Real-time monitoring of radiofrequency ablation and postablation assessment: accuracy of contrast-enhanced US in experimental rat liver model

PURPOSE

To examine the accuracy of the unenhanced zone at contrast material-enhanced ultrasonography (US) in predicting coagulative necrosis during and 21 days after radiofrequency (RF) ablation by using radiologic-pathologic comparison.

MATERIALS AND METHODS

Animal studies were approved by the Institutional Animal Care and Use Committee. The livers of 28 rats underwent US-guided RF ablation. In four animals, contrast-enhanced US was performed during ablation and 2 hours and 2, 7, 14, and 21 days after ablation. The unenhanced zone area on US images was measured. DiI-labeled microbubbles were administered during ablation at 2, 4, and 6 minutes or at 2 hours and 2, 7, 14, and 21 days after ablation in the remaining 24 animals (n = 3 at each time point). One minute later, the animal was euthanized, and the ablated liver was harvested. Tissue samples were imaged to quantify total fluorescence, and NADH staining was performed on the same slice. Hematoxylin-eosin staining was also performed. The findings on fluorescence images, NADH-stained images, and hematoxylin-eosin-stained images were compared. The areas of DiI bubble-negative zones, NADH-negative zones, and lightly NADH-staining zones were measured. Data were analyzed by using one-way analysis of variance.

RESULTS

The area of the unenhanced zone on contrast-enhanced US images increased during RF ablation and reached a maximum within 2 days after ablation. At histopathologic examination, a transition zone manifested adjacent to the coagulation zone until 2 days after ablation. The DiI-bubble negative zone on fluorescence images and the damaged zone (transition zone plus coagulation zone) on NADH-stained images increased rapidly within 2 hours after ablation, then slowly reached the maximum on day 2. The ratios of the mean areas of these two zones at hour 2 to those at day 2 were 94.6% and 95.6%, respectively. High uniformity between the damaged zone on NADH-stained images and the DiI bubble-negative zone on fluorescence images was noted at all time points.

CONCLUSION

The temporary transition zone in NADH staining is partially damaged and should transition to nonviability 2 days after ablation. These results demonstrate that contrast-enhanced US can help delineate the maximum area of cell damage (to within 5% of the maximum) as early as 2 hours after ablation. Contrast-enhanced US may be a simple and accurate tool for monitoring the effects of RF ablation and quantifying the size of thermal damage after treatment.

Outcomes after pulmonary metastasectomy for colorectal cancer

BACKGROUND

Surgical resection offers the greatest likelihood of cure for appropriately selected patients with pulmonary colorectal carcinoma metastases. We hereby report our experience over the last 19 years at the Austin Hospital, Thoracic Surgery Unit.

METHODS

This is a retrospective study of a consecutive series of patients with pulmonary colorectal cancer metastases. From 1994 to 2012, 66 patients underwent 83 pulmonary metastasectomies for colorectal cancer at the Austin Hospital.

RESULTS

Seventy per cent of patients were operated on for single pulmonary metastases. The most common procedure performed was a video-assisted thoracoscopic surgery wedge resection. Median follow-up duration was 25 months. Three-, five-, seven- and ten-year survival was 53.4, 39.6, 34.6 and 23.1%, respectively.

CONCLUSION

Pulmonary metastasectomy for metastatic colorectal carcinoma continues to offer the greatest survival advantage for appropriately selected patients.

Ki 67 is an independent predictive biomarker of cancer specific and local recurrence-free survival after lung tumor ablation

BACKGROUND

The objective of this work was to evaluate the feasibility of histopathological analysis of tissue extracted on multitined electrodes and assess whether tissue characteristics can be used as biomarkers of oncologic outcomes after lung tumor radiofrequency (RF) ablation.

METHODS

Treatment-related data regarding RF ablation of lung malignancies at our institution was collected using a Health Insurance Portability and Accountability Act-compliant ablation database. Institutional review board waiver was obtained for this study. Immunohistochemical analysis of tissue extracted from the electrodes after lung tumor RF ablation was performed for proliferation (Ki-67) and apoptosis (caspase-3). Patient, tumor demographics, and ablation parameters were recorded. Local tumor progression-free survival (LPFS), disease-specific survival (DSS), and overall survival (OS) were assessed using Kaplan-Meier methodology. Multivariate analysis determined factors affecting these oncological outcomes.

RESULTS

A total of 47 lung tumors in 42 patients were ablated; 30 specimens were classified as coagulation necrosis (CN) and 17 as Ki-67-positive (+) tumor cells (viable). Tumor sizes were similar in the CN and Ki-67+ groups (P = 0.32). Median LPFS was 10 versus 16 months for Ki-67+ and CN groups, and 1-year LPFS was 34 and 75 %, respectively (P = 0.003). Median OS was 20 and 46 months (P = 0.12), and median DSS was 20 and 68 months (P = 0.01) for the Ki-67 + and CN groups, respectively. Identification of Ki-67+ tumor cells more than tripled the risk of death from cancer [hazard ratio (HR) = 3.65; 95 % confidence interval (95 % CI), 1.34-9.95; P = 0.01] and tripled the risk of local tumor progression (LTP) (HR = 3.01; 95 % CI, 1.39-6.49; P = 0.005).

CONCLUSIONS

Ki-67+ tumor cells on the electrode after pulmonary tumor RF ablation is an independent predictor of LTP, shorter LPFS, and DSS.

Review of the mathematical functions used to model the temperature dependence of electrical and thermal conductivities of biological tissue in radiofrequency ablation

PURPOSE

Although theoretical modelling is widely used to study different aspects of radiofrequency ablation (RFA), its utility is directly related to its realism. An important factor in this realism is the use of mathematical functions to model the temperature dependence of thermal (k) and electrical (σ) conductivities of tissue. Our aim was to review the piecewise mathematical functions most commonly used for modelling the temperature dependence of k and σ in RFA computational modelling.

MATERIALS AND METHODS

We built a hepatic RFA theoretical model of a cooled electrode and compared lesion dimensions and impedance evolution with combinations of mathematical functions proposed in previous studies. We employed the thermal damage contour D63 to compute the lesion dimension contour, which corresponds to Ω = 1, Ω being local thermal damage assessed by the Arrhenius damage model.

RESULTS

The results were very similar in all cases in terms of impedance evolution and lesion size after 6 min of ablation. Although the relative differences between cases in terms of time to first roll-off (abrupt increase in impedance) were as much as 12%, the maximum relative differences in terms of the short lesion (transverse) diameter were below 3.5%.

CONCLUSIONS

The findings suggest that the different methods of modelling temperature dependence of k and σ reported in the literature do not significantly affect the computed lesion diameter.

Microsimulation model predicts survival benefit of radiofrequency ablation and stereotactic body radiotherapy versus radiotherapy for treating inoperable stage I non-small cell lung cancer

OBJECTIVE

A subset of patients with stage IA and IB non-small cell lung cancer (NSCLC) is ineligible for surgical resection and undergoes radiation therapy. Radiofrequency ablation (RFA) and stereotactic body radiotherapy are newer potentially attractive alternative therapies.

MATERIALS AND METHODS

We added RFA and stereotactic body radiotherapy treatment modules to a microsimulation model that simulates lung cancer's natural history, detection, and treatment. Natural history parameters were previously estimated via calibration against tumor registry data and cohort studies; the model was validated with screening study and cohort data. RFA model parameters were calibrated against 2-year survival from the Radiofrequency Ablation of Pulmonary Tumor Response Evaluation (RAPTURE) study, and stereotactic body radiotherapy model parameters were calibrated against 3-year survival from a phase 2 prospective trial. We simulated lifetime histories of identical patients with early-stage NSCLC who were ineligible for resection, who were treated with radiation therapy, RFA, or stereotactic body radiotherapy under a range of scenarios. From 5,000,000 simulated individuals, we selected a cohort of patients with stage I medically inoperable cancer for analysis (n = 2056 per treatment scenario). Main outcomes were life expectancy gains.

RESULTS

RFA or stereotactic body radiotherapy treatment in patients with peripheral stage IA or IB NSCLC who were nonoperative candidates resulted in life expectancy gains of 1.71 and 1.46 life-years, respectively, compared with universal radiation therapy. A strategy where patients with central tumors underwent stereotactic body radiotherapy and those with peripheral tumors underwent RFA resulted in a gain of 2.02 life-years compared with universal radiation therapy. Findings were robust with respect to changes in model parameters.

CONCLUSION

Microsimulation modeling results suggest that RFA and stereotactic body radiotherapy could provide life expectancy gains to patients with stage IA or IB NSCLC who are ineligible for resection.

Microwave ablation of pulmonary malignancies using a novel high-energy antenna system

PURPOSE

To evaluate the technical success, safety, and imaging follow-up of malignant pulmonary nodules treated with a novel high-energy percutaneous microwave ablation (MWA) system.

METHODS

Between July 2010 and September 2011, a total of 23 patients, 12 men, mean age 68 (range 30-87) years with 29 pulmonary malignancies of median diameter 19 (range 8-57) mm, underwent computed tomography (CT)-guided MWA with a 16G microwave needle antenna enabling power up to 180 W. Technical success was defined as needle placement in the intended lesion without death or serious injury. Adequacy of ablation was assessed at 24 h on contrast-enhanced CT. Circumferential solid or ground glass opacification >5 mm was used to define an ideal ablation. Local tumor recurrence was assessed at 1, 3, and 6 months after ablation on contrast-enhanced CT.

RESULTS

MWA was technically successful in 93 % (n = 27). Mean ablation duration was 3.6 (range 1-9) min. Ten patients (43 %) developed a pneumothorax as a result of the MWA; only 3 (13 %) required placement of a chest drain. Thirty-day mortality rate was 0 %. The mean hospital stay was 1.5 (range 1-7) days. A total of 22 lesions (75 %) were surrounded by ≥5 mm ground glass or solid opacification after the procedure. At a median follow-up of 6 months, local recurrence was identified in 3 out of 26 lesions, giving a local control rate of 88 %.

CONCLUSION

MWA using a high-power antenna of pulmonary malignancies is safe, technically achievable, and enables fast ablation times.

Thermal ablation in the treatment of lung cancer: present and future

Surgery is considered the best choice for stage I non-small cell lung cancer and also in treatment of selected patients with lung metastasis. However, surgery is often a high-risk procedure because of severe medical comorbidities affecting this cohort of patients. Thermal ablation (TA) has recently been proposed to achieve destruction of lung tumours whilst avoiding the use of general anaesthesia, thereby limiting the invasiveness of the procedure. For pulmonary malignancies, there are two methods of TA based on tissue heating: radio frequency ablation (RFA) and microwave ablation (MWA). Both are mini-invasive procedures, delivering energy to the tumour through single or multiple percutaneous needles introduced under guidance of computed tomography. The procedure may be performed under conscious sedation or general anaesthesia to avoid pain caused by needle insertion and tissue heating. Local efficacy is directly correlated to tumour target size: for RFA, tumours smaller than 2 cm can be completed ablated in 78-96% of cases; for MWA-according to the largest available study-95% of initial ablations are reported to be successful for tumours smaller than 5 cm. Very few series provide survival data beyond 3 years. For nodules smaller than 3 cm, the registered survival rate is higher: 50% at five years. The data collected in the last 10 years allow us to conclude that TA is an established alternative treatment for patients who cannot undergo surgery because of their compromised general condition. In the case of pulmonary metastasis, most authors agree to offer TA only if lesions are smaller than 5 cm.

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.

Recurrent non-small cell lung cancer: evaluation of CT-guided radiofrequency ablation as salvage therapy

BACKGROUND

Radiofrequency ablation (RFA) is a potential application as a salvage tool after failure of surgery, chemotherapy, or radiotherapy of non-small cell lung cancer (NSCLC). Although several studies have evaluated the use of RFA in primary NSCLC, there is little literature on its potential application as a salvage tool.

PURPOSE

To evaluate CT-guided RFA employed as a salvage therapy for pulmonary recurrences of NSCLC after prior treatment with chemotherapy, radiation therapy, and/or surgery.

MATERIAL AND METHODS

A retrospective computer database search yielded 33 patients with biopsy proven primary NSCLC who underwent CT-guided RFA of 39 recurrent tumors following surgery, chemotherapy, and/or radiotherapy. Follow-up imaging was performed with CT and PET-CT. The endpoints of interest were progression-free survival (PFS) and time to local progression (TTLP). PFS and TTLP were compared by lesion size (<3 cm, ≥3 cm).

RESULTS

The median PFS was 8 months. For patients with a tumor size <3 cm median PFS was 11 months, whereas the median PFS of patients with a tumor size ≥3 cm was 5 months. The difference did not reach statistical significance (P = 0.09). The median TTLP of all tumors was 14 months. TTLP of ablated tumors <3 cm in size was 24 months, compared to 8 months for ablated tumors ≥3 cm in size. The difference did not reach statistical significance (P = 0.07).

CONCLUSION

RFA of recurrent NSCLC may be a valuable salvage tool to achieve local tumor control, especially in tumors measuring <3 cm in size.

Treatment of pulmonary colorectal metastases by radiofrequency ablation

We evaluated the local tumor control and the survival benefit achieved with radiofrequency ablation (RFA) for nonoperable lung metastases in 45 patients with colorectal cancer. Median survival from the time of RFA was 46 months. One-, 2- and 3-year local tumor progression (LTP)-free survival rates were 92%, 77%, and 77%, respectively. RFA offers very good local control in patients with pulmonary metastases from colorectal cancer.

BACKGROUND

Radiofrequency ablation has emerged as a potential, lung function-preserving treatment of colorectal lung metastases.

PATIENTS AND METHODS

Forty-five patients with colorectal pulmonary metastases underwent computed tomography-guided RFA from December 2004 to June 2010. A baseline posttreatment scan was obtained 4-6 weeks after RFA and follow-up imaging studies every 3 months thereafter were obtained and compared to evaluate the tumor progression at site of ablation or elsewhere. The primary end points were LTP-free survival and overall survival from RFA procedure. The Kaplan-Meier method was used to analyze the end points. A Cox proportional hazard model with robust inference was used to estimate the associations between baseline factors and survival end points.

RESULTS

Sixty-nine metastases were ablated in 45 patients. Tumor size ranged from 0.4 to 3.5 cm. The median number of metastases ablated per patient was 1 (range, 1-3). Median follow-up after RFA was 18 months. Median survival from the time of RFA was 46 months (95% confidence interval [CI], 27.8-47.3). One-, 2- and 3-year overall survival rates from the time of RFA were 95% (95% CI, 82%-99%), 72% (95% CI, 52%-85%), and 50% (95% CI, 26%-71%), respectively. Nine of 69 lesions (13%) progressed and 4 were retreated with no progression after second RFA. Median time to progression was not reached. LTP-free survival from RFA was 92% (95% CI, 82%-97%) at 1 year, 77% (95% CI, 58%-88%) at 2 years, and 77% (95% CI, 58%-88%) at 3 years.

CONCLUSION

Radiofrequency ablation of lung metastases is an effective minimally invasive, parenchymal-sparing technique that has very good local control rates in patients with pulmonary metastases from colorectal cancer, with LTP-free survival of 77% at 3 years.

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.

Current status of thermal ablation treatments for lung malignancies

About 75% of lung cancer patients are not surgical candidates, either due to advanced disease or medical comorbidities. Furthermore, conventional treatments that can be offered to these patients are beneficial only to a small percentage of them. Thermal ablation is a minimally invasive treatment that is commonly used in this group of patients, and which has shown promising results. Currently, the most widely used ablation techniques in the treatment of lung malignancies are radiofrequency ablation (RFA), microwave ablation, and cryoablation. Although the most studied technique is RFA, recent studies with microwave ablation and cryoablation have shown some advantages over RFA. This article reviews the application of thermal ablation in the thorax, including patient selection, basic aspects of procedure technique, imaging follow-up, treatment outcomes, and comparison of ablation techniques.

Radiofrequency ablation of pulmonary neoplasm complicated by pulmonary hemorrhage

Pulmonary hemorrhage is a potentially serious complication of radiofrequency ablation of pulmonary neoplasms that may occur with or without hemoptysis. Several factors influence the development of parenchymal hemorrhage, including tumor size, tumor location, and procedural technique. As radiofrequency ablation has become more common, the prompt diagnosis and appropriate treatment of hemorrhage is vital. The authors report a case of radiofrequency ablation of a solitary pulmonary metastasis complicated by pulmonary hemorrhage and hemoptysis.

In vivo evaluation of lung microwave ablation in a porcine tumor mimic model

PURPOSE

To evaluate the microwave ablation of created tumor mimics in the lung of a large animal model (pigs), with examination of the ablative synergy of multiple antennas.

METHODS

Fifty-six tumor-mimic models of various sizes were created in 15 pigs by using barium-enriched minced collected thigh muscle injected into the lung of the same animal. Tumors were ablated under fluoroscopic guidance by single-antenna and multiple-antenna microwaves.

RESULTS

Thirty-five tumor models were treated in 11 pigs with a single antenna at 75 W for 15 min, with 15 measuring 20 mm in diameter, 10 measuring 30 mm, and 10 measuring 40 mm. Mean circularity of the single-antenna ablation zones measured 0.64 ± 0.12, with a diameter of 35.7 ± 8.7 mm along the axis of the antenna and 32.7 ± 12.8 mm perpendicular to the feeding point. Multiple-antenna delivery of 75 W for 15 min caused intraprocedural death of 2 animals; modified protocol to 60 W for 10 min resulted in an ablation zone with a diameter of 43.0 ± 7.7 along the axis of the antenna and 54.8 ± 8.5 mm perpendicular to the feeding point; circularity was 0.70 ± 0.10

CONCLUSIONS

A single microwave antenna can create ablation zones large enough to cover lung tumor mimic models of ≤4 cm with no heat sink effect from vessels of ≤6 mm. Synergic use of 3 antennas allows ablation of larger volumes than single-antenna or radiofrequency ablation, but great caution must be taken when 3 antennas are used simultaneously in the lung in clinical practice.

[Radiofrequency ablation for the treatment of lung neoplasms: a retrospective study of 329 cases]

背景与目的

射频消融（radiofrequency ablation, RFA）是近年来用于无法手术的肺部恶性肿瘤及肺转移瘤治疗的替代方案。本研究旨在评估肺射频消融术的安全性和临床疗效。

方法

本研究回顾性分析1999年10月-2006年7月在第四军医大学唐都医院胸腔外科进行肺部恶性肿瘤射频消融术的患者329例（其中肺部原发肿瘤237例，转移瘤92例），对其进行射频治疗后的并发症、局部进展以及1年、2年和5年总生存期的临床资料进行了研究及评价分析。

结果

行射频手术的患者术后出现的并发症包括：气胸63例（19.1%），咯血14例（死亡1例，4.2%），血胸10例（3.0%），肺炎15例（4.5%）和心包填塞3例（死亡1例，0.9%），术后30天内的死亡率为0.6%，针道肿瘤种植的患者6例（1.8%）。中位无进展时间为21.6个月。1年、2年和5年总生存率分别为68.2%、35.3%和20.1%。共有78例（23.7%）患者出现后期肿瘤局部进展。肺部肿瘤原位局部进展的患者的肿瘤包块直径大多 > 4 cm; 在肿瘤局部进展方面，肿瘤 < 3 cm的患者与直径介于3 cm-4 cm的肿瘤患者相比没有明显差异，这两组患者与直径 > 4 cm的肿瘤患者间存在明显差异。

结论

对于肺部恶性肿瘤来说，射频治疗是一种耐受性良好、疗效可靠安全的治疗方法。

Image-guided thermal ablation of lung malignancies

Primary and secondary lung malignancies are often treated with surgery. Many patients are poor surgical candidates owing to advanced age or medical comorbidities. Alternatives to surgery for localized disease include radiation therapy and the newer treatments known as image-guided thermal ablation. Image-guided thermal ablation involves the use of needlelike applicators that are placed directly into tumors by using imaging guidance. Tumors are destroyed by the application of either intense heat or cold. The specific ablative modalities of radiofrequency ablation, microwave ablation, laser ablation, and cryoablation are reviewed with respect to the various clinical indications for treatment of both primary and secondary lung malignancies.

Bipolar radio frequency ablation of spinal neoplasms in late stage cancer disease: a report of three cases

STUDY DESIGN

Case report.

OBJECTIVE

To avoid neuronal damage by using the bipolar radio frequency ablation of spinal tumors.

SUMMARY OF BACKGROUND DATA

Radio frequency ablation of tumorous masses is an established procedure and is increasingly used as pain therapy of unresectable spine tumors. Ablation of lesions adjacent to vulnerable structures remains a challenging task because flow of current is insufficiently controlled by monopolar probes. Using this technique, a prediction of the induced necrosis accurate to the millimeter is not feasible.

METHODS

Three patients with metastases of the spine were treated using the bipolar radio frequency ablation.

RESULTS

In all 3 cases collateral damage of neuronal structures could be avoided even though tumorous masses touched the cauda equina or were very close to vulnerable structures, respectively. The induction of necrosis was predictable to the millimeter.

CONCLUSION

Ablation of tumorous masses adjacent to neural structures by bipolar technique, is feasible and predictable. Spinal cord damage can be avoided by exact planning of the induced necrosis.

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.

[Serious complications after pulmonary radiofrequency ablation: report of 2 cases]

Radiofrequency ablation can be used to treat primary or metastatic pulmonary tumors when surgery is not indicated or involves high risk. Although this technique is less invasive than surgical resection, it is not free of risk for complications and adverse events, especially when it is used in patients with serious respiratory disease in whom comorbidity is common. We report 2 cases of serious complications. One was an intractable air leak that led to death. The other was a large hemothorax that was brought under control in the radiology procedure room. We review the literature on this technique as well as recommendations that contribute to making it as safe as possible.