Discrepancy Between Achieved and Vendor-Predicted Ablation Zones in the Lung: Contributing Factors

PURPOSE

Several factors are known to affect lung ablation zones. Questions remain as to why there are discrepancies between achieved and vendor-predicted ablation zones and what contributing factors can be modified to balance therapeutic effects with avoidance of complications. This retrospective study of lung tumour microwave ablation analyses day 1 post-treatment CT to assess the effects of lesion-specific and operator-dependent factors on ablation zones.

METHODS AND MATERIALS

Consecutive patients treated at a tertiary centre from 2018 to 2021 were included. All ablations were performed using a single microwave ablation device under lung isolation. The lung tumours were categorised as primary or secondary, and their "resistance" to ablation was graded according to their locations. Intraprocedural pulmonary inflation was assessed as equal to or less than the contralateral non-isolated lung. Ablation energy was categorised as high, medium, or low. Ablation zone dimensions were measured on day 1 CT and compared to vendor reference charts. Ablations with multiple needle positions or indeterminate boundaries were excluded.

RESULTS

A total of 47 lesions in 31 patients were analysed. Achieved long axes are longer than predicted by 5 mm or 14% (p < 0.01) without overall short axis discrepancy. Secondary tumours (p = 0.020), low-resistance location (p < 0.01), good lung inflation (p < 0.01), low (p = 0.003) and medium (p = 0.038) total energy produce lengthened long axes by 4-6 mm or 10-19%. High total energy results in shorter than predicated short axes by 6 mm or 18% (p = 0.010).

CONCLUSION

We identified several factors affecting ablation zone dimensions which may have implications for ablation planning and the avoidance of complications.

Cone-beam computed tomography image-guided percutaneous microwave ablation for lung nodules in a hybrid operating room: an initial experience

OBJECTIVES

The experience of thermal ablation of lung lesions is limited, especially performing the procedure under localisation by cone-beam CT in the hybrid operation room (HOR). Here, we present the experience of microwave ablation (MWA) of lung nodules in the HOR.

METHODS

We reviewed patients who underwent image-guide percutaneous MWA for lung nodules in the HOR under general anaesthesia between July 2020 and July 2022. The workflow in the HOR including the pre-procedure preparation, anaesthesia consideration, operation methods, and postoperative care was clearly described.

RESULTS

Forty lesions in 33 patients who underwent MWA under general anaesthesia (GA) in the HOR were analysed. Twenty-seven patients had a single pulmonary nodule, and the remaining six patients had multiple nodules. The median procedure time was 41.0 min, and the median ablation time per lesion was 6.75 min. The median global operation room time was 115.0 min. The median total dose area product was 14881 μGym2. The median ablation volume was 111.6 cm3. All patients were discharged from the hospital with a median postoperative stay of 1 day. Four patients had pneumothorax, two patients had pleural effusion during the first month of outpatient follow-up, and one patient reported intercostal neuralgia during the 3-month follow-up.

CONCLUSIONS

Thermal ablation of pulmonary nodules under GA in the HOR can be performed safely and efficiently if we follow the workflow provided. The procedure provides an alternative to managing pulmonary nodules in patients.

CLINICAL RELEVANCE STATEMENT

Thermal ablation of pulmonary nodules under GA in the HOR can be performed safely and efficiently if the provided workflow is followed.

KEY POINTS

• We tested the feasibility of microwave ablation of lung lesions performed in a hybrid operating room. • To this end, we provide a description of microwave ablation of the lung under cone-beam CT localisation. • We describe a workflow by which ablation of the pulmonary nodule can be performed safely under general anaesthesia.

Enhancing precision in lung tumor ablation through innovations in CT-guided technique and angle control

BACKGROUND

This retrospective study aimed to evaluate the precision and safety outcomes of image-guided lung percutaneous thermal ablation (LPTA) methods, focusing on radiofrequency ablation (RFA) and microwave ablation (MWA). The study utilized an innovative angle reference guide to facilitate these techniques in the treatment of lung tumors.

METHODS

This study included individuals undergoing LPTA with the assistance of laser angle guide assembly (LAGA) at our hospital between April 2011 and March 2021. We analyzed patient demographics, tumor characteristics, procedure details, and complications. Logistic regressions were employed to assess risk factors associated with complications.

RESULTS

A total of 202 patients underwent ablation for 375 lung tumors across 275 sessions involving 495 ablations. Most procedures used RFA, especially in the right upper lobe, and the majority of ablations were performed in the prone position (49.7%). Target lesions were at a median depth of 39.3 mm from the pleura surface, and remarkably, 91.9% required only a single puncture. Complications occurred in 31.0% of ablations, with pneumothorax being the most prevalent (18.3%), followed by pain (12.5%), sweating (6.5%), fever (5.0%), cough (4.8%), hemothorax (1.6%), hemoptysis (1.2%), pleural effusion (2.0%), skin burn (0.6%), and air emboli (0.2%). The median procedure time was 21 min. Notably, smoking/chronic obstructive pulmonary disease emerged as a significant risk factor for complications.

CONCLUSION

The LAGA-assisted LPTA enhanced safety by improving accuracy and reducing risks. Overall, this investigation contributes to the ongoing efforts to refine and improve the clinical application of these thermal ablation techniques in the treatment of lung tumors.

Protect the recurrent laryngeal nerves in US-guided microwave ablation of thyroid nodules at Zuckerkandl tubercle: a pilot study

BACKGROUND

To evaluate the safety and efficacy of US-guided microwave ablation in patients with thyroid nodules at Zuckerkandl tubercle.

METHODS

103 consecutive patients with thyroid nodules at Zuckerkandl tubercle (ZTTN) were enrolled in this study from November 2017 to August 2021. Prior to the surgery or US-guided microwave ablation (MWA), preoperative ultrasound visualization of the recurrent laryngeal nerve (RLN) and ZTTN was performed, the size and the position relationship between them were observed. Patients were followed up at 1, 3, 6, and 12 months after MWA and the volume reduction rates (VRR) of the thyroid nodules were analyzed.

RESULTS

All patients successfully had the RLN and ZTTN detected using ultrasound before surgery or ablation with a detection rate of 100%. For the 103 patients, the majority of ZTTN grades were categorized as grade 2, with the distance from the farthest outside of ZTTN to the outer edge of thyroid ranging between 6.0 and 10.0 mm. The position relationship between ZTTN and RLN was predominantly type A in 98 cases, with type D observed in 5 cases. After MWA, the median nodule volume had significantly decreased from 4.61 (2.34, 8.70) ml to 0.42 (0.15, 1.41) ml and the VRR achieved 84.36 ± 13.87% at 12 months. No nodules regrew throughout the 12-month follow-up period. Of the 11 patients experienced hoarseness due to RLN entrapment before ablation, 7 recovered immediately after separation of the RLN and ZTTN during MWA, 2 recovered after one week, and the other 2 recovered after two months.

CONCLUSIONS

The RLN is closely related to ZTTN and mainly located at the back of ZTTN. The RLN can be separated from ZTTN by hydrodissection during MWA. US-guided MWA is a safe and effective treatment for ZTTN.

Treatment strategies for malignant pulmonary nodule: beyond lobectomy. Point-counterpoint

PURPOSE OF REVIEW

Technological advancement in low-dose computed tomography resulted in an increased incidental discovery of early-stage lung cancer and multifocal ground glass opacity. The demand for parenchyma-preserving treatment strategies is greater now than ever. Pulmonary ablative therapy is a groundbreaking technique to offer local ablative treatment in a lung-sparing manner. It has become a promising technique in lung cancer management with its diverse applicability. In this article, we will review the current development of ablative therapy in lung and look into the future of this innovative technique.

RECENT FINDINGS

Current literature suggests that ablative therapy offers comparable local disease control to other local therapies and stereotactic body radiation therapy (SBRT), with a low risk of complications. In particular, bronchoscopic microwave ablation (BMWA) has considerably fewer pleural-based complications due to the avoidance of pleural puncture. BMWA can be considered in the multidisciplinary treatment pathway as it allows re-ablation and allows SBRT after BMWA.

SUMMARY

With the benefits which ablative therapy offers and its ability to incorporate into the multidisciplinary management pathway, we foresee ablative therapy, especially BMWA gaining significance in lung cancer treatment. Future directions on developing novel automated navigation platforms and the latest form of ablative energy would further enhance clinical outcomes for our patients.

Efficacy and safety of radiofrequency ablation in the treatment of inoperable patients with pulmonary malignant nodules

BACKGROUND

Radiofrequency ablation (RFA) has been recently applied as an alternative treatment in the patients with pulmonary malignancies. The aim of our study was to assess the incidence of complications and survival rate of RFA for malignant lung nodules, and evaluate the efficacy and safety of RFA in the treatment of inoperable patients with pulmonary malignant nodules.

METHODS

The clinical data of 50 patients with primary and metastatic lung malignant nodules treated with RFA from June 2015 and July 2017 in Hebei General Hospital were considered, and the characteristics and clinical data of these patients were analysed. Complications, progression-free survival and overall survival at 1, 2 and 5 years of these patients were evaluated.

RESULTS

Following the procedure. There were no major complications and deaths during the operation. 26 (52%) patients presented mild-to-moderate chest pain that was easily controlled by analgesic drugs. 8 (16%) patients with pneumothorax, 4 (8%) haemoptysis, 6 (12%) pneumonia, 7 (14%) pleural effusion and 1 (2%) postoperative bronchopleural fistula. Needle-track implantation was observed in 2 (4%) patients. Median progression-free survival (PFS) was 24.6 months. The PFS at 1, 2, 5 years was 76%, 52% and 20%, respectively. Median overall survival (OS) was 35.5 months. The OS at 1, 2 and 5 years was 80%, 58% and 32%, respectively.

CONCLUSION

RFA is a safe and effective alternative treatment for the inoperable patients with primary or metastatic pulmonary malignant nodules. The clinical impact and long-term results of RFA need to be further confirmed in a larger series of patients, and RFA should ideally be compared with surgery.

Potential biomarkers for predicting immune response and outcomes in lung cancer patients undergoing thermal ablation

Thermal ablation is a promising alternative treatment for lung cancer. It disintegrates cancer cells and releases antigens, followed by the remodeling of local tumor immune microenvironment and the activation of anti-tumor immune responses, enhancing the overall effectiveness of the treatment. Biomarkers can offer insights into the patient's immune response and outcomes, such as local tumor control, recurrence, overall survival, and progression-free survival. Identifying and validating such biomarkers can significantly impact clinical decision-making, leading to personalized treatment strategies and improved patient outcomes. This review provides a comprehensive overview of the current state of research on potential biomarkers for predicting immune response and outcomes in lung cancer patients undergoing thermal ablation, including their potential role in lung cancer management, and the challenges and future directions.

Primary and Metastatic Lung Cancer: Rationale, Indications, and Outcomes of Thermal Ablation

The widespread use of imaging as well as the efforts conducted through screening campaigns has dramatically increased the early detection rate of lung cancer. Historically, the management of lung cancer has heavily relied on surgery. However, the increased proportion of patients with comorbidities has given significance to less invasive therapeutic options like minimally invasive surgery and image-guided thermal ablation, which could precisely target the tumor without requiring general anesthesia or a thoracotomy. Thermal ablation is considered low-risk for lung tumors smaller than 3 cm that are located in peripheral lung and do not involve major blood vessels or airways. The rationale for ablative therapies relies on the fact that focused delivery of energy induces cell death and pathologic necrosis. Image-guided percutaneous thermal ablation therapies are established techniques in the local treatment of hepatic, renal, bone, thyroid and uterine lesions. In the lung, and specifically in the setting of metastatic disease, the 3 main indications for lung ablation are to serve as (1) curative intent, (2) as a strategy to achieve a chemo-holiday in oligometastatic disease, and (3) in oligoprogressive disease. Following these premises, the current paper aims to review the rationale, indications, and outcomes of thermal ablation as a form of local therapy in the treatment of primary and metastatic lung disease.

Stage IV Colorectal Cancer Management and Treatment

(1) Background: Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related mortality worldwide. Up to 50% of patients with CRC develop metastatic CRC (mCRC). Surgical and systemic therapy advances can now offer significant survival advantages. Understanding the evolving treatment options is essential for decreasing mCRC mortality. We aim to summarize current evidence and guidelines regarding the management of mCRC to provide utility when making a treatment plan for the heterogenous spectrum of mCRC. (2) Methods: A comprehensive literature search of PubMed and current guidelines written by major cancer and surgical societies were reviewed. The references of the included studies were screened to identify additional studies that were incorporated as appropriate. (3) Results: The standard of care for mCRC primarily consists of surgical resection and systemic therapy. Complete resection of liver, lung, and peritoneal metastases is associated with better disease control and survival. Systemic therapy now includes chemotherapy, targeted therapy, and immunotherapy options that can be tailored by molecular profiling. Differences between colon and rectal metastasis management exist between major guidelines. (4) Conclusions: With the advances in surgical and systemic therapy, as well as a better understanding of tumor biology and the importance of molecular profiling, more patients can anticipate prolonged survival. We provide a summary of available evidence for the management of mCRC, highlighting the similarities and presenting the difference in available literature. Ultimately, a multidisciplinary evaluation of patients with mCRC is crucial to selecting the appropriate pathway.

Transbronchial Techniques for Lung Cancer Treatment: Where Are We Now?

The demand for parenchyma-sparing local therapies for lung cancer is rising owing to an increasing incidence of multifocal lung cancers and patients who are unfit for surgery. With the latest evidence of the efficacy of lung cancer screening, more premalignant or early-stage lung cancers are being discovered and the paradigm has shifted from treatment to prevention. Transbronchial therapy is an important armamentarium in the local treatment of lung cancers, with microwave ablation being the most promising based on early to midterm results. Adjuncts to improve transbronchial ablation efficiency and accuracy include mobile C-arm platforms, software to correct for the CT-to-body divergence, metal-containing nanoparticles, and robotic bronchoscopy. Other forms of energy including steam vapor therapy and pulse electric field are under intensive investigation.

Percutaneous image-guided thermal ablation of lung cancer: What is the evidence?

Thermal ablation techniques have now been used for more than twenty years in the treatment of primary lung tumours, predominantly non-small cell lung cancer (NSCLC). Although primarily used for the treatment of early-stage disease in non-surgical patients, thermal ablation is now also being used in selected patients with oligometastatic and oligoprogressive disease. This review discusses the techniques available for thermal ablation, the evidence for use of thermal ablation in primary lung tumours in early- and advanced-stage disease and compares thermal ablation to alternative treatment strategies.

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.

CT-guided percutaneous microwave ablation for pulmonary metastases from colorectal cancer: Prognosis analyses based on the origin of the primary tumor

BACKGROUND

Microwave ablation (MWA) is becoming an effective therapy for inoperable pulmonary metastases from colorectal cancer (CRC). However, it is unclear whether the primary tumor location affects survival after MWA.

OBJECTIVE

This study aims to investigate the survival outcomes and prognostic factors of MWA based on different primary origins between colon and rectal cancer.

METHODS

Patients who underwent MWA for pulmonary metastases from 2014 to 2021 were reviewed. Differences in survival outcomes between colon and rectal cancer were analyzed with the Kaplan-Meier method and log-rank tests. The prognostic factors between groups were then evaluated by univariable and multivariable Cox regression analyses.

RESULTS

A total of 118 patients with 154 pulmonary metastases from CRC were treated in 140 MWA sessions. Rectal cancer had a higher proportion with seventy (59.32% ) than colon cancer with forty-eight (40.68% ). The average maximum diameter of pulmonary metastases from rectal cancer (1.09 cm) was greater than that of colon cancer (0.89 cm; p = 0.026). The median follow-up was 18.53 months (range 1.10 - 60.63 months). The disease-free survival (DFS) and overall survival (OS) in colon and rectal cancer groups were 25.97 vs 11.90 months (p = 0.405), and 60.63 vs 53.87 months (p = 0.149), respectively. Multivariate analyses showed that only age was an independent prognostic factor in patients with rectal cancer (HR = 3.70, 95% CI: 1.28 - 10.72, p = 0.023), while none in colon cancer.

CONCLUSIONS

Primary CRC location has no impact on survival for patients with pulmonary metastases after MWA, while a disparate prognostic factor exists between colon and rectal cancer.

Safety and Efficacy Outcomes From a Single-Center Study of Image-Guided Percutaneous Microwave Ablation for Primary and Metastatic Lung Malignancy

Introduction

Image-guided percutaneous microwave ablation (MWA) is becoming a more common treatment option for patients with primary and metastatic lung malignancies. Nevertheless, there is limited literature on the safety and efficacy of MWA compared with standard-of-care therapy, including surgical resection and radiation. This study will report the long-term outcomes after MWA for pulmonary malignancies and investigate the factors related to efficacy, including lesion size, location, and ablation power.

Methods

Retrospective single-center study analyzing 93 patients who underwent percutaneous MWA for primary or metastatic lung malignancies. Outcomes included immediate technical success, local tumor recurrence, overall survival, disease-specific survival, and complications.

Results

At a single institution, 190 lesions (81 primary and 109 metastatic) were treated in 93 patients. Immediate technical success was achieved in all cases. Freedom from local recurrence was 87.6%, 75.3%, and 69.2% and overall survival was 87.7%, 76.2%, and 74.3% at 1 year, 2 years, and 3 years, respectively. Disease-specific survival was 92.6%, 81.8%, and 81.8%. The most common complication was pneumothorax, which occurred in 54.7% (104 of 190) of procedures, with 35.2% (67 of 190) requiring a chest tube. No life-threatening complications occurred.

Conclusions

Percutaneous MWA seems safe and effective for treatment of primary and metastatic lung malignancies and should be considered for patients with limited metastatic burden and lesions less than 3 cm in size.

Image-guided percutaneous ablation for lung malignancies

Image-guided percutaneous lung ablation has proven to be an alternative and effective strategy in the treatment of lung cancer and other lung malignancies. Radiofrequency ablation, microwave ablation, and cryoablation are widely used ablation modalities in clinical practice that can be performed along or combined with other treatment modalities. In this context, this article will review the application of different ablation strategies in lung malignancies.

MRI-guided microwave ablation and albumin-bound paclitaxel for lung tumors: Initial experience

Magnetic resonance-guided microwave ablation (MRI-guided MWA) is a new, minimally invasive ablation method for cancer. This study sought to analyze the clinical value of MRI-guided MWA in non-small cell lung cancer (NSCLC). We compared the precision, efficiency, and clinical efficacy of treatment in patients who underwent MRI-guided MWA or computed tomography (CT)-guided microwave ablation (CT-guided MWA). Propensity score matching was used on the prospective cohort (MRI-MWA group, n = 45) and the retrospective observational cohort (CT-MWA group, n = 305). To evaluate the advantages and efficacy of MRI-guided MWA, data including the accuracy of needle placement, scan duration, ablation time, total operation time, length of hospital stay, progression-free survival (PFS), and overall survival (OS) were collected and compared between the two groups. The mean number of machine scans required to adjust the needle position was 7.62 ± 1.69 (range 4–12) for the MRI-MWA group and 9.64 ± 2.14 (range 5–16) for the CT-MWA group (p < 0.001). The mean time for antenna placement was comparable between the MRI and CT groups (54.41 ± 12.32 min and 53.03 ± 11.29 min, p = 0.607). The microwave ablation time of the two groups was significantly different (7.62 ± 2.65 min and 9.41 ± 2.86 min, p = 0.017), while the overall procedure time was comparable (91.28 ± 16.69 min vs. 93.41 ± 16.03 min, p = 0.568). The overall complication rate in the MRI-MWA group was significantly lower than in the CT-MWA group (12% vs. 51%, p = 0.185). The median time to progression was longer in the MRI-MWA group than in the CT-MWA group (11 months [95% CI 10.24–11.75] vs. 9 months [95% CI 8.00–9.99], p = 0.0003; hazard ratio 0.3690 [95% CI 0.2159–0.6306]). OS was comparable in both groups (MRI group 26.0 months [95% CI 25.022–26.978] vs. CT group 23.0 months [95% CI 18.646–27.354], p = 0.18). This study provides hitherto-undocumented evidence of the clinical effects of MRI-guided MWA on patients with NSCLC and determines the relative safety and efficiency of MRI- and CT-guided MWA.

Prediction of Ablation Volume in Percutaneous Lung Microwave Ablation: A Single Centre Retrospective Study

BACKGROUND

Percutaneous Microwave Ablation (MWA) of lung malignancies is a procedure with many technical challenges, among them the risk of residual disease. Recently, dedicated software able to predict the volume of the ablated area was introduced. Cone-beam computed tomography (CBCT) is the imaging guidance of choice for pulmonary ablation in our institution. The volumetric prediction software (VPS) has been installed and used in combination with CBCT to check the correct position of the device. Our study aimed to compare the results of MWA of pulmonary tumours performed using CBCT with and without VPS.

METHODS

We retrospectively reviewed 1-month follow-up enhanced contrast-enhanced computed tomography (CECT) scans of 10 patients who underwent ablation with the assistance of VPS (group 1) and of 10 patients who were treated without the assistance of VPS (group 2). All patients were treated for curative purposes, the maximum axial diameter of lesions ranged between 5 and 22 mm in group 1 and between 5 and 25 mm in group 2. We compared the presence of residual disease between the two groups.

RESULTS

In group 1 residual disease was seen in only 1 patient (10%) in which VPS had ensured complete coverage of the tumour. In group 2 residual disease was found in 3 patients (30%).

CONCLUSIONS

Using this software during MWA of lung malignancies could improve the efficacy of the treatment compared to the conventional only CBCT guidance.

Long-term outcome following microwave ablation of lung metastases from colorectal cancer

Purpose

To retrospectively evaluate the safety and efficacy of percutaneous computed tomography (CT)-guided microwave ablation (MWA) in colorectal cancer (CRC) lung metastases, and to analyze prognostic factors.

Materials and methods

Data were collected from 31 patients with CRC lung metastases from May 2013 to September 2017. They had removed the CRC, no extrapulmonary metastases, no more than three metastases in the lung, the maximum diameter of the lesions was ≤3 cm, and all the lung metastases could be completely ablated. The ablation procedures were performed using a KY-2000 microwave multifunctional therapeutic apparatus. Efficacy is assessed two to four weeks after ablation, and follow-up are performed every three months for two years. The primary outcome was overall survival (OS). The secondary outcomes were progression-free survival (PFS), and complications. Cox regression analysis was used for the evaluation of the statistical significance of factors affecting the end result of MWA therapy. The Kaplan–Meier method was used for estimation of survival rates.

Results

A total of 45 metastatic lung lesions from CRC in 31 patients were treated with CT-guided MWA procedures. The median OS was 76 months. The one, two, three, and five-year survival rates were 93.5%, 80.6%, 61.3%, and 51.6%, respectively. Multivariate analysis showed that the primary tumor from the rectum (P = 0.009) and liver metastases at the diagnosis of lung metastases (P = 0.043) were risk factors affecting OS, while PFS was a protective factor. The median PFS was 13 months. The maximum diameter of lung metastases lesions (P = 0.004) was a risk factor. The interval between pulmonary metastases and MWA (P=0.031) was the protective factor. Pneumothorax was observed in 13 out of 36 procedures. Four patients developed pneumothorax requiring drainage tube insertion. No patient deaths occurred within 30 days of ablation. Three out of 31 patients (9.67%) were found to have local recurrence of the original lung metastatic ablation foci.

Conclusion

MWA therapy may be safely and effectively used as a therapeutic tool for the treatment of selected CRC pulmonary metastases, and the prognosis is better in patients without liver metastases at the diagnosis of lung metastases.

Development of a novel MR-conditional microwave needle for MR-guided interventional microwave ablation at 1.5T

PURPOSE

To develop an MR-conditional microwave needle that generates a spherical ablation zone and clear MRI visibility for MR-guided microwave ablation.

METHODS

An MR-conditional microwave needle consisting of zirconia tip and TA18 titanium alloy tube was investigated. The numerical model was created to optimize the needle's geometry and analyze its performance. A geometrically optimized needle was produced using non-magnetic materials based on the electromagnetics simulation results. The needle's mechanical properties were tested per the Chinese pharmaceutical industry standard YY0899-2013. The MRI visibility performance and ablation characteristics of the needle was tested both in vitro (phantom) and in vivo (rabbit) at 1.5T. The RF-induced heating was evaluated in ex vivo porcine liver.

RESULTS

The needle's mechanical properties met the specified requirements. The needle susceptibility artifact was clearly visible both in vitro and in vivo. The needle artifact diameter (A) was small in in vivo (A_shaft: 4.96 ± 0.18 mm for T1W-FLASH, 3.13 ± 0.05 mm for T2-weighted fast spin-echo (T2W-FSE); A_tip: 2.31 ± 0.09 mm for T1W-FLASH, 2.29 ± 0.08 mm for T2W-FSE; tip location error [TLE]_: -0.94 ± 0.07 mm for T1W-FLASH, -1.10 ± 0.09 mm for T2W-FSE). Ablation zones generated by the needle were nearly spherical with an elliptical aspect ratio ranging from 0.79 to 0.90 at 30 W, 50 W for 3, 5, 10 min duration ex vivo ablations and 0.86 at 30 W for 10 min duration in vivo ablations.

CONCLUSION

The designed MR-conditional microwave needle offers excellent mechanical properties, reliable MRI visibility, insignificant RF-induced heating, and a sufficiently spherical ablation zone. Further clinical development of MR-guided microwave ablation appears warranted.

Integrated Treatment Planning in Percutaneous Microwave Ablation of Lung Tumors

Microwave ablation (MWA) is a clinically widespread minimally invasive treatment method for lung tumors. Preoperative planning plays a vital role in MWA therapy. However, previous planning methods are far from satisfactory in clinical practice because they only one-sidedly consider the surgical path or energy parameters of an MWA surgery. In this paper, we propose a novel planning model with a computational model of thermal damage to integrally optimize both the surgical path and energy parameters. To ensure the model can be solved in a reasonable time, we elaborate a search space reducing strategy based on clinical constraints. Simulation and ex vivo experimental results were compared with an average mean absolute error of 0.82 K and an average root mean square error of 1.01 K. Our planning model was evaluated on clinical data, and the experimental results demonstrate the effectiveness of our model.

Highly efficient magnetic ablation and the contrast of various imaging using biocompatible liquid-metal gallium

Background

Although the powerful clinical effects of radiofrequency and microwave ablation have been established, such ablation is associated with several limitations, including a small ablation size, a long ablation time, the few treatment positioning, and biosafety risks. To overcome these limitations, biosafe and efficient magnetic ablation was achieved in this study by using biocompatible liquid gallium as an ablation medium and a contrast medium for imaging.

Results

Magnetic fields with a frequency (f) lower than 200 kHz and an amplitude (H) × f value lower than 5.0 × 10⁹ Am⁻¹ s⁻¹ were generated using the proposed method. These fields could generate an ablation size of 3 cm in rat liver lobes under a temperature of approximately 300 °C and a time of 20 s. The results of this study indicate that biomedical gallium can be used as a contrast medium for the positioning of gallium injections and the evaluation of ablated tissue around a target site. Liquid gallium can be used as an ablation medium and imaging contrast medium because of its stable retention in normal tissue for at least 3 days. Besides, the high anticancer potential of gallium ions was inferred from the self-degradation of 100 µL of liquid gallium after around 21 days of immersion in acidic solutions.

Conclusions

The rapid wireless ablation of large or multiple lesions was achieved through the simple multi-injection of liquid gallium. This approach can replace the currently favoured procedure involving the use of multiple ablation probes, which is associated with limited benefits and several side effects.

Methods

Magnetic ablation was confirmed to be highly efficient by the consistent results obtained in the simulation and in vitro tests of gallium and iron oxide as well as the electromagnetic specifics and thermotherapy performance comparison detailed in this study Ultrasound imaging, X-ray imaging, and magnetic resonance imaging were found to be compatible with the proposed magnetic ablation method. Self-degradation analysis was conducted by mixing liquid gallium in acidic solutions with a pH of approximately 5–7 (to imitate a tumour-containing microenvironment). X-ray diffraction was used to identify the gallium oxides produced by degraded gallium ions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12938-022-01003-9.

Comparison of expected imaging findings following percutaneous microwave and cryoablation of pulmonary tumors: ablation zones and thoracic lymph nodes

OBJECTIVE

To compare temporal changes of ablation zones and lymph nodes following lung microwave ablation (MWA) and cryoablation.

METHODS

This retrospective cohort study compared lung ablation zones and thoracic lymph nodes following MWA and cryoablation performed 2006-2020. In the ablation zone cohort, ablation zone volumes were measured on serial CT for 12 months. In the lymph node cohort, the sum of bidimensional products of lymph node diameters was measured before (baseline) and up to 6 months following ablation. Cumulative incidence curves estimated the time to 75% ablation zone reduction and linear mixed-effects regression models compared the temporal distribution of ablation zones and lymph node sizes between modalities.

RESULTS

Ablation zones of 59 tumors treated in 45 sessions (16 MWA, 29 cryoablation) in 36 patients were evaluated. Differences in the time to 75% volume reduction between modalities were not detected. Following MWA, half of the ablation zones required an estimated time of 340 days to achieve a 75% volume reduction compared to 214 days following cryoablation (p = .30). Thoracic lymph node sizes after 33 sessions (13 MWA, 20 cryoablation) differed between modalities (baseline-32 days, p = .01; 32-123 days, p = .001). Following MWA, lymph nodes increased on average by 38 mm² (95%CI, 5.0-70.7; p = .02) from baseline to 32 days, followed by an estimated decrease of 50 mm² (32-123 days; p = .001). Following cryoablation, changes in lymph nodes were not detected (baseline-32 days, p = .33).

CONCLUSION

The rate of ablation zone volume reduction did not differ between MWA and cryoablation. Thoracic lymph nodes enlarged transiently after MWA but not after cryoablation.

KEY POINTS

• Contrary to current belief, the rate of lung ablation zone volume reduction did not differ between microwave and cryoablation. • Transient enlargement of thoracic lymph nodes after microwave ablation was not associated with regional tumor spread and decreased within six months following ablation. • No significant thoracic lymph node enlargement was observed following cryoablation.

The Latest on Lung Ablation

Lung cancer is the second most common cancer in both men and women. Despite smoking cessation efforts and advances in lung cancer detection and treatment, long-term survival remains low. For early-stage primary lung carcinoma, surgical resection offers the best chance of long-term survival; however, only about one-third of patients are surgical candidates. For nonsurgical candidates, minimally invasive percutaneous thermal ablation therapies have become recognized as safe and effective treatment alternatives, including radiofrequency ablation, microwave ablation, and cryoablation. Lung ablation is also an acceptable treatment for limited oligometastatic and oligorecurrent diseases. This article discusses the technologies and techniques available for tumor ablation of thoracic malignancies, as well as new treatments on the horizon.

CT-guided Percutaneous Cryoablation in Patients with Lung Nodules Mainly Composed of Ground-Glass Opacities

PURPOSE

To assess the safety and efficacy of cryoablation in patients with lung nodules mainly composed of ground-glass opacities (GGOs).

MATERIALS AND METHODS

In this retrospective study, 50 patients (mean age, 65.0 ± 12.3; 28 women) diagnosed with lung GGO nodules who underwent cryoablation were included (from June 2016-June 2021). The local recurrence rate, the incidence of regional metastases to lymph nodes, the incidence of distant metastases, adverse events, and the lung function condition were analyzed.

RESULTS

Follow-up computed tomography (CT) was performed an average of 33 months (range, 3-60 months) after the cryoablation procedure. Outcomes were only evaluated in 30 patients. A total of 20 patients were excluded: 10 patients had no cancer detected at histopathological analysis and were diagnosed with CT scan or positron emission tomography-CT (PET/CT), and the other 10 patients had nodules with a diameter of less than 10 mm and a consolidation-to-tumor ratio (CTR) of more than 0.25, and thus histopathological analysis was not performed due to small nodule size and patients were diagnosed with CT or PET/CT. The local recurrence rate was 0% (0 of 30). Evidence of regional metastases of the lymph nodes was not found in any patients (0%; 0 of 30), and the incidence of distant metastases was 0% (0 of 30). No major complications were noted. Lung function recovered to normal within one month after cryoablation in all patients.

CONCLUSION

Cryoablation may serve as a safe and feasible option for the treatment of lung nodules mainly composed of GGOs.

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.

CT after Lung Microwave Ablation: Normal Findings and Evolution Patterns of Treated Lesions

Imaging-guided percutaneous ablative treatments, such as radiofrequency ablation (RFA), cryoablation and microwave ablation (MWA), have been developed for the treatment of unresectable primary and secondary lung tumors in patients with advanced-stage disease or comorbidities contraindicating surgery. Among these therapies, MWA has recently shown promising results in the treatment of pulmonary neoplasms. The potential advantages of MWA over RFA include faster ablation times, higher intra-tumoral temperatures, larger ablation zones and lower susceptibility to the heat sink effect, resulting in greater efficacy in proximity to vascular structures. Despite encouraging results supporting its efficacy, there is a relative paucity of data in the literature regarding the role of computer tomography (CT) to monitor MWA-treated lesions, and the CT appearance of their morphologic evolution and complications. For both interventional and non-interventional radiologists, it is crucial to be familiar with the CT features of such treated lesions in order to detect incomplete therapy or recurrent disease at early stage, as well as to recognize initial signs of complications. The aim of this pictorial essay is to describe the typical CT features during follow-up of lung lesions treated with percutaneous MWA and how to interpret and differentiate them from other radiological findings, such as recurrence and complications, that are commonly encountered in this setting.

Microwave ablation treatment for medically inoperable stage I non-small cell lung cancers: long-term results

OBJECTIVES

In the present study, we aim to show the results of microwave ablation (MWA) for medically inoperable stage I non-small cell lung cancers (NSCLCs) with long-term follow-up.

METHODS

From Feb 2011 to Mar 2016, patients with histologically proven clinical stage I NSCLC were treated with CT-guided MWA and retrospectively analyzed. The primary end point was overall survival (OS). Secondary end points included disease-free survival (DFS), cancer-specific survival (CSS), and complications.

RESULTS

A total of 105 patients with 105 lesions underwent MWA. The mean age was 70.7 years (range: 40-86 years), and the mean diameter of all lesions was 2.40 cm (range: 0.9-4.0 cm). Adenocarcinoma was the most common histological type (77, 73.3%), followed by squamous cell carcinomas (21, 20%) and undefined NSCLC (7, 6.7%). With a median follow-up of 54.8 months, the median DFS was 36.0 months, and 1-, 3-, and 5-year DFS rates were 89.5%, 49.4%, and 42.7%, respectively. The median CSS and OS were 89.8 and 64.2 months, respectively. The OS rate was 99% at 1 year, 75.6% at 3 years, and 54.1% at 5 years, while the CSS rates were 99%, 78.9%, and 60.9%, respectively. Patients with stage IB lesions had significant shorter DFS (22.3 months vs. undefined, HR: 11.5, 95%CI: 5.85-22.40) and OS (37.3 vs. 89.8 months, HR: 8.64, 95% CI: 4.49-16.60) than IA disease.

CONCLUSION

MWA is a safe, effective, and potentially curative therapy for medically inoperable stage I NSCLC patients.

KEY POINTS

• In this multicenter retrospective study which included 105 patients, we found the median overall survival (OS) was 64.2 months. The OS rate was 99% at 1 year, 75.6% at 3 years, and 54.1% at 5 years. • Procedures were technically successful and well tolerated in all patients. Most MWA complications were mild or moderate.

[Application and Progress of Electromagnetic Navigation Bronchoscopy in Department of Thoracic Surgery]

Lung cancer ranks the first cancer-related morbidity and mortality in China. With the development and penetration of imaging technology, increasing small pulmonary peripheral Nodules (SPPNs) have been detected. However, precise location and diagnosis of SPPNs is still a tough problem for clinical diagnosis and treatment in department of thoracic surgery. With the development of electromagnetic navigation bronchoscopy (ENB), it provides a novel minimally invasive method for the diagnosis and treatment of SPPNs. In this review, we summarized the application and progress of ENB in preoperative positioning, diagnosis, and local treatment, then, discussed the clinical application of ENB in the hybrid operating room.
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Methods of monitoring thermal ablation of soft tissue tumors - A comprehensive review

Thermal ablation is a form of hyperthermia in which oncologic control can be achieved by briefly inducing elevated temperatures, typically in the range 50-80°C, within a target tissue. Ablation modalities include high intensity focused ultrasound, radiofrequency ablation, microwave ablation, and laser interstitial thermal therapy which are all capable of generating confined zones of tissue destruction, resulting in fewer complications than conventional cancer therapies. Oncologic control is contingent upon achieving predefined coagulation zones; therefore, intraoperative assessment of treatment progress is highly desirable. Consequently, there is a growing interest in the development of ablation monitoring modalities. The first section of this review presents the mechanism of action and common applications of the primary ablation modalities. The following section outlines the state-of-the-art in thermal dosimetry which includes interstitial thermal probes and radiologic imaging. Both the physical mechanism of measurement and clinical or pre-clinical performance are discussed for each ablation modality. Thermal dosimetry must be coupled with a thermal damage model as outlined in Section 4. These models estimate cell death based on temperature-time history and are inherently tissue specific. In the absence of a reliable thermal model, the utility of thermal monitoring is greatly reduced. The final section of this review paper covers technologies that have been developed to directly assess tissue conditions. These approaches include visualization of non-perfused tissue with contrast-enhanced imaging, assessment of tissue mechanical properties using ultrasound and magnetic resonance elastography, and finally interrogation of tissue optical properties with interstitial probes. In summary, monitoring thermal ablation is critical for consistent clinical success and many promising technologies are under development but an optimal solution has yet to achieve widespread adoption.

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.

Efficacy of Lung-Tuned Monopole Antenna for Microwave Ablation: Analytical Solution and Validation in a Ventilator-Controlled ex Vivo Porcine Lung Model

The goal of this study was to optimize a lung-tuned monopole antenna to deliver microwave energy at 2.45 GHz into a novel ventilator-controlled ex vivo lung model. An analytic and parametric approach was utilized to create an optimized monopole antenna that was impedance-matched to aerated lung tissue. This lung-tuned antenna was then fabricated using a copper 0.085" semi-rigid copper coaxial cable. For validation, the lung-tuned antenna was inserted centrally into lobes of a ex vivo porcine lung that was fully inflated to physiologically appropriate volumes. Microwave ablations were then created at 50 and 100 W for 1 minute and 5 minutes. Reflected power, cross sectional ablation sizes and spherical shape of the lung-tuned antenna were compared against a liver-tuned antenna in the ventilator-controlled ex vivo lung tissue. The study showed that the lung-tuned antennas delivered energy significantly more efficiently, with less reflected power, compared to the conventionally-used liver-tuned antennas at 50 W at 1 minute (11.8±3.0 vs 16.3±3.1 W; p value=0.03) and 5 minutes (16.2±2.8 vs 19.4±2.9 W; p value=0.04), although this was only true using 100 W at the 1 minute time point (29.0±3.5 vs 38.0±5.3 W; p value=0.02). While overall ablation zone sizes were comparable between the two types of antenna, the lung-tuned antenna did create a significantly more spherical ablation zone compared to the liver-tuned antenna at the 1 minute, 50 W setting (aspect ratio: 0.43±0.07 vs 0.38±0.04; p value=0.04). In both antenna groups, there was a significant rise in the ablation zone aspect ratio between 1 and 5 minutes, indicating that higher power and time settings can increase the spherical shape of ablation zones when using tuned antennas. Adapting this combined analytic and parametric approach to antenna design can be implemented in adaptive tissue-tuning for real-time microwave ablation optimization in lung tissue.

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.

Current Management of Oligometastatic Lung Cancer and Future Perspectives: Results of Thermal Ablation as a Local Ablative Therapy

A growing body of evidence shows improved overall survival and progression-free survival after thermal ablation in non-small cell lung carcinoma (NSCLC) patients with a limited number of metastases, combined with chemotherapy or tyrosine kinase inhibitors or after local recurrence. Radiofrequency ablation and microwave ablation are the most evaluated modalities, and target tumor size <3 cm (and preferably <2 cm) is a key factor of technical success and efficacy. Although thermal ablation offers some advantages over surgery and radiotherapy in terms of repeatability, safety, and quality of life, optimal management of these patients requires a multidisciplinary approach, and further randomized controlled trials are required to help refine patient selection criteria. In this article, we present a comprehensive review of available thermal ablation modalities and recent results supporting their use in oligometastatic and oligoprogressive NSCLC disease along with their potential future implications in the emerging field of immunotherapy.

Comparison of Percutaneous Image-Guided Microwave and Cryoablation for Sarcoma Lung Metastases: 10-Year Experience

Background: Outcomes between percutaneous microwave (MWA) and cryoablation of sarcoma lung metastases have not been compared to our knowledge. Objective: To compare technical success, complications, local tumor control, and overall survival (OS) following MWA versus cryoablation of sarcoma lung metastases. Methods: This retrospective cohort study included 27 patients (16 women, 11 men; median age 64 years; Eastern Cooperative Oncology Group performance score 0-2) who underwent 39 percutaneous CT-guided ablation sessions (21 MWA, 18 cryoablation; 1-4 sessions per patient) to treat 65 sarcoma lung metastases (median 1 tumor per patient, range 1-12; median tumor diameter 11 mm, range 5-33 mm; 25% non-peripheral) from 2009 to 2021. We compared complications by ablation modality using generalized-estimating equations. We evaluated ablation modality, tumor size, and location (peripheral vs non-peripheral) in relation to local tumor progression using proportional Cox hazard models with death as competing risk. We estimated OS using the Kaplan-Meier method. Results: Primary technical success was 97% for both modalities. Median follow-up was 23 months (range: 1-102 months; interquartile range: 12, 44 months). A total of 7/61 (12%) tumors progressed. Estimated 1-year and 2-year local control rates were, for tumors >1 cm, 97% and 95% following MWA versus 99% and 98% following cryoablation, and for tumors ≤1 cm, 74% and 62% following MWA versus 86% and 79% following cryoablation. Tumor size ≤1 cm was associated with decreased cumulative incidence of local progression (p =.048); ablation modality and tumor location were not associated with progression (p =.86; p =.54). Complications (CTCAE grade ≤3) occurred in 17/39 sessions (44%), prompting chest tube placement in nine (23%). No complications with grade ≥4 occurred. OS at 1-, 2-, and 3-years was 100%, 89%, and 82%, respectively. Conclusion: High primary technical success, local control, and OS support MWA and cryoablation for treating sarcoma lung metastases. Ablation modality and tumor location did not affect local progression. Treatment failure was low, especially for small tumors. No life-threatening complications occurred. Clinical Impact: Percutaneous MWA and cryoablation are both suited for treatment of sarcoma lung metastases, especially for tumors ≤1 cm, whether peripheral or non-peripheral. Complications, if they occur, are not life-threatening.

Local progression after computed tomography-guided microwave ablation in non-small cell lung cancer patients: prediction using a nomogram model

OBJECTIVES

To develop an effective nomogram model for predicting the local progression after computed tomography-guided microwave ablation (MWA) in non-small cell lung cancer (NSCLC) patients.

METHODS

NSCLC patients treated with MWA were randomly allocated to either the training cohort or the validation cohort (4:1). The predictors of local progression identified by univariable and multivariable analyses in the training cohort were used to develop a nomogram model. The C-statistic was used to evaluate the predictive accuracy in both the training and validation cohorts.

RESULTS

A total of 304 patients (training cohort: n = 250; validation cohort: n = 54) were included in this study. The predictors selected into the nomogram for local progression included the tumor subtypes (odds ratio [OR], 2.494; 95% confidence interval [CI], 1.415-4.396, p = 0.002), vessels ≥3 mm in direct contact with tumor (OR, 2.750; 95% CI, 1.263-5.988; p = 0.011), tumor diameter (OR, 2.252; 95% CI, 1.034-4.903; p = 0.041) and location (OR, 2.442; 95% CI, 1.201-4.965; p = 0.014). The C-statistic showed good predictive performance in both cohorts, with a C-statistic of 0.777 (95% CI, 0.707-0.848) internally and 0.712 (95% CI, 0.570-0.855) externally (training cohort and validation cohort, respectively). The optimal cutoff value for the risk of local progression was 0.39.

CONCLUSIONS

Tumor subtypes, vessels ≥3 mm in direct contact with the tumor, tumor diameter and location were predictors of local progression after MWA in NSCLC patients. The nomogram model could effectively predict the risk of local progression after MWA. Patients showing a high risk (>0.39) on the nomogram should be monitored for local progression.

Lung Ablation with Irreversible Electroporation Promotes Immune Cell Infiltration by Sparing Extracellular Matrix Proteins and Vasculature: Implications for Immunotherapy

Background: This study investigated the sparing of the extracellular matrix (ECM) and blood vessels at the site of lung irreversible electroporation (IRE), and its impact on postablation T cell and macrophage populations. Materials and Methods: Normal swine (n = 8) lung was treated with either IRE or microwave ablation (MWA), followed by sacrifice at 2 and 28 days (four animals/timepoint) after treatment. En bloc samples of ablated lung were stained for blood vessels (CD31), ECM proteins (Collagen, Heparan sulfate, and Decorin), T cells (CD3), and macrophages (Iba1). Stained slides were analyzed with an image processing software (ImageJ) to count the number of positive staining cells or the percentage area of tissue staining for ECM markers, and the statistical difference was evaluated with Student's t-test. Results: Approximately 50% of the blood vessels and collagen typically seen in healthy lung were evident in IRE treated samples at Day 2, with complete destruction within MWA treated lung. These levels increased threefold by Day 28, indicative of post-IRE tissue remodeling and regeneration. Decorin and Heparan sulfate levels were reduced, and it remained so through the duration of observation. Concurrently, numbers of CD3⁺ T cells and macrophages were not different from healthy lung at Day 2 after IRE, subsequently increasing by 2.5 and 1.5-fold by Day 28. Similar findings were restricted to the peripheral inflammatory rim of MWA samples, wherein the central necrotic regions remained acellular through Day 28. Conclusion: Acute preservation of blood vessels and major ECM components was observed in IRE treated lung at acute time points, and it was associated with the increased infiltration and presence of T cells and macrophages, features that were spatially restricted in MWA treated lung.

Computed tomography-guided microwave ablation for the treatment of non-small cell lung cancer patients with and without adjacent lobe invasion: A comparative study

BACKGROUND

The aim of the study was to explore the outcomes of computed tomography-guided microwave ablation (MWA) in non-small cell lung cancer (NSCLC) patients with adjacent lobe invasion (ALI), and to compare the outcomes of ALI-NSCLC and non-ALI NSCLC patients after MWA.

METHODS

A total of 319 NSCLC patients and 366 tumors treated with MWA were included in the study, comprising 34 ALI-NSCLC patients and 285 non-ALI NSCLC patients. Complications, local recurrence rates, progression-free survival (PFS), and overall survival (OS) were compared. Logistic regression analyses were used to investigate the correlation between ALI and the occurrence of pneumothorax after MWA.

RESULTS

The mean tumor diameter of ablated tumors was 3.6 ± 2.2 cm. There were 95 (29.8%) NSCLC patients in which pneumothorax occurred after MWA, and all patients recovered. Of these, the ALI group had a significantly higher incidence rate of pneumothorax than the non-ALI group (52.9% vs. 27.0%, p = 0.002). The median PFS and OS for the ALI group were 12.0 ± 10.2 and 15.5 ± 9.5 months, respectively, and that of the non-ALI group were 13.0 ± 10.6 and 17.0 ± 11.1 months, respectively, and no significant difference was found in PFS (p = 0.329) nor OS (p = 0.394) between the two groups. Local recurrence rates for ALI and non-ALI groups were 29.4% and 20.7%, respectively, and no significant difference was found (p = 0.244). Logistic regression analyses revealed that ALI can increase the risk of pneumothorax (hazard ratio [HR], 2.867; p = 0.012).

CONCLUSIONS

MWA is an effective and safe approach for ALI-NSCLC treatment. Although ALI can increase the risk of pneumothorax, ALI-NSCLC patients reveal a comparable outcome to non-ALI NSCLC patients after MWA.

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.

Microwave ablation of lung malignancies with coexisting severe emphysema: a retrospective analysis of safety and efficacy in 26 patients

PURPOSE

This retrospective study aimed to evaluate the safety and efficacy of microwave ablation (MWA) for lung malignancies in patients with severe emphysema.

MATERIALS AND METHODS

The clinical records of 1075 consecutive patients treated for malignant lung tumors in our department were retrospectively reviewed. Emphysema was assessed based on standard-dose computed tomography (CT) and was considered severe when it occupied ≥25% of the lung. Overall, 26 patients (24 men and 2 women; mean age ± standard deviation [SD]: 71.23 ± 8.18 years, range: 59-88 years) with severe emphysema underwent CT-guided percutaneous MWA for treating 26 tumors (24: non-small cell lung cancer and 2: metastases). The mean tumor size was 3.0 cm (SD: 1.5, range: 1.2-6.5 cm). Follow-up was performed with CT at 1, 3, 6, 12 months after ablation, and every 6 months thereafter. Complications and efficacy were evaluated.

RESULTS

The median follow-up duration in all patients was 17.5 months (range: 5-37 months, interquartile range: 15.8). The mortality rate was 0% within 30 days after ablation. Major complications including pneumonia, lung abscess and refractory pneumothorax occurred in 19.2% (5/26) patients. The technical success and efficacy rates were 88.5% (23/26) and 87.0% (20/23), respectively, and the local tumor progression rate was 30.0% (6/20).

CONCLUSION

MWA appears to be a safe and effective therapeutic option for treating lung malignancies in patients with severe emphysema.

CT-based quantitative evaluation of the efficacy after radiofrequency ablation in patients with benign thyroid nodules

OBJECTIVE

The purpose of this study was to evaluate the usefulness of CT for quantitative assessment of the neck structures after RFA in patients with benign thyroid nodules.

MATERIALS AND METHODS

This single-center, retrospective cohort study included 38 patients with benign thyroid nodules who had received RFA and had available pre- and post-treatment CT images. Changes in the tracheal anteroposterior (AP)/transverse diameter ratio, cross-sectional tracheal area, midline deviation of the trachea, and anterior neck angle after RFA were quantitatively measured using CT. Volume reduction rates (VRRs) for the thyroid gland and nodules were measured using CT and US, respectively, and the intraclass correlation coefficient (ICC) was calculated. The paired Wilcoxon signed-rank test was used to compare pre- and post-treatment CT-based measurements, and univariate linear regression analysis was performed to determine the association of VRR with the mean delivered radiofrequency energy, number of RFA sessions, and initial thyroid volume.

RESULTS

After RFA, the tracheal AP/transverse diameter ratio and midline deviation were significantly decreased while the tracheal area and anterior neck angle were significantly increased (all, p < 0.001). The thyroid volume reduction was also significant (VRR, 42.1% ± 21.1%, p < 0.001), with moderate consistency between the CT-based thyroid VRR and US-based nodule VRR (ICC = 0.68, 95% confidence interval = 0.38-0.83, p < 0.001). The mean delivered radiofrequency energy (p = 0.565), number of RFA sessions (p = 0.209), and initial thyroid volume (p = 0.363) showed no significant association with VRR.

CONCLUSION

CT-based quantitative assessments may be useful for evaluating improvements in the neck structures after RFA for benign thyroid nodules.

Assessment of safety margin after microwave ablation of stage I NSCLC with three-dimensional reconstruction technique using CT imaging

Objective

To assess the ablative margin of microwave ablation (MWA) for stage I non-small cell lung cancer (NSCLC) using a three-dimensional (3D) reconstruction technique.

Materials and methods

We retrospectively analyzed 36 patients with stage I NSCLC lesions undergoing MWA and analyzed the relationship between minimal ablative margin and the local tumor progression (LTP) interval, the distant metastasis interval and disease-free survival (DFS). The minimal ablative margin was measured using the fusion of 3D computed tomography reconstruction technique.

Results

Univariate and multivariate analyses indicated that tumor size (hazard ratio [HR] = 1.91, P < 0.01; HR = 2.41, P = 0.01) and minimal ablative margin (HR = 0.13, P < 0.01; HR = 0.11, P < 0.01) were independent prognostic factors for the LTP interval. Tumor size (HR = 1.96, P < 0.01; HR = 2.35, P < 0.01) and minimal ablative margin (HR = 0.17, P < 0.01; HR = 0.13, P < 0.01) were independent prognostic factors for DFS by univariate and multivariate analyses. In the group with a minimal ablative margin < 5 mm, the 1-year and 2-year local progression-free rates were 35.7% and 15.9%, respectively. The 1-year and 2-year distant metastasis-free rates were 75.6% and 75.6%, respectively; the 1-year and 2-year disease-free survival rates were 16.7% and 11.1%, respectively. In the group with a minimal ablative margin ≥ 5 mm, the 1-year and 2-year local progression-free rates were 88.9% and 69.4%, respectively. The 1-year and 2-year distant metastasis-free rates were 94.4% and 86.6%, respectively; the 1-year and 2-year disease-free survival rates were 88.9% and 63.7%, respectively. The feasibility of 3D quantitative analysis of the ablative margins after MWA for NSCLC has been validated.

Conclusions

The minimal ablative margin is an independent factor of NSCLC relapse after MWA, and the fusion of 3D reconstruction technique can feasibly assess the minimal ablative margin.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12880-021-00626-z.

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.

Microwave ablation of lung tumors: A probabilistic approach for simulation-based treatment planning

PURPOSE

Microwave ablation (MWA) is a clinically established modality for treatment of lung tumors. A challenge with existing application of MWA, however, is local tumor progression, potentially due to failure to establish an adequate treatment margin. This study presents a robust simulation-based treatment planning methodology to assist operators in comparatively assessing thermal profiles and likelihood of achieving a specified minimum margin as a function of candidate applied energy parameters.

METHODS

We employed a biophysical simulation-based probabilistic treatment planning methodology to evaluate the likelihood of achieving a specified minimum margin for candidate treatment parameters (i.e., applied power and ablation duration for a given applicator position within a tumor). A set of simulations with varying tissue properties was evaluated for each considered combination of power and ablation duration, and for four different scenarios of contrast in tissue biophysical properties between tumor and normal lung. A treatment planning graph was then assembled, where distributions of achieved minimum ablation zone margins and collateral damage volumes can be assessed for candidate applied power and treatment duration combinations. For each chosen power and time combination, the operator can also visualize the histogram of ablation zone boundaries overlaid on the tumor and target volumes. We assembled treatment planning graphs for generic 1, 2, and 2.5 cm diameter spherically shaped tumors and also illustrated the impact of tissue heterogeneity on delivered treatment plans and resulting ablation histograms. Finally, we illustrated the treatment planning methodology on two example patient-specific cases of tumors with irregular shapes.

RESULTS

The assembled treatment planning graphs indicate that 30 W, 6 min ablations achieve a 5-mm minimum margin across all simulated cases for 1-cm diameter spherical tumors, and 70 W, 10 min ablations achieve a 3-mm minimum margin across 90% of simulations for a 2.5-cm diameter spherical tumor. Different scenarios of tissue heterogeneity between tumor and lung tissue revealed 2 min overall difference in ablation duration, in order to reliably achieve a 4-mm minimum margin or larger each time for 2-cm diameter spherical tumor.

CONCLUSIONS

An approach for simulation-based treatment planning for microwave ablation of lung tumors is illustrated to account for the impact of specific geometry of the treatment site, tissue property uncertainty, and heterogeneity between the tumor and normal lung.

A Comparative Study of Cavitary and Noncavitary Non-small Cell Lung Cancer Patients Treated with CT-Guided Microwave Ablation

PURPOSE

To explore the outcomes of computed tomography‒guided microwave (MW) ablation in patients with cavitary non-small cell lung cancer (NSCLC) and to compare the outcomes of cavitary and noncavitary NSCLC treated with MW ablation.

MATERIALS AND METHODS

A total of 317 patients with NSCLC (194 men and 123 women) treated with MW ablation were include: 19 patients with cavitary NSCLC and 298 patients with noncavitary NSCLC. Complications, progression-free survival (PFS), and overall survival (OS) were evaluated and compared between the 2 groups. The Kaplan-Meier method was used to investigate the correlation of cavity and OS in patients with NSCLC.

RESULTS

A total of 364 MW ablation procedures were performed. Adenocarcinoma was the predominant histopathological subtype in patients with cavitary NSCLC (73.7%). Cavitary NSCLC had an incidence rate of 57.9% in overall complications, which was significantly higher than that of 34.6% for noncavitary NSCLC (P = .040). In a mean follow-up of 27.2 months ± 11.9, the median PFS and OS for cavitary NSCLC were 9.0 months ± 8.5 and 14.0 months ± 10.8, respectively, and those for noncavitary NSCLC were 13.0 months ± 10.7 and 17.0 months ± 10.9, respectively. There was no significant difference in PFS (P = .180) or OS (P = .133) between cavitary and noncavitary NSCLC. In addition, the local recurrence rates for cavitary and noncavitary NSCLC were 15.8% and 21.5%, respectively, and no significant difference was found (P = .765). The Kaplan-Meier method revealed no association between the cavity and OS in patients with NSCLC treated with MW ablation.

CONCLUSIONS

MW ablation was an effective and safe approach for cavitary NSCLC treatment. Compared with noncavitary NSCLC, cavitary NSCLC manifested with more complications but a comparable outcome after MW ablation.

Active Versus Passive Thaw Following Percutaneous Cryoablation of Pulmonary Tumors: Effect on Incidence, Grade, and Onset of Hemoptysis

Background: Hemoptysis is common following percutaneous image-guided cryoablation of pulmonary tumors. Objective: To evaluate the effect of a final active thaw on the incidence, grade, and onset of hemoptysis following percutaneous cryoablation of pulmonary tumors. Methods: This retrospective cohort study included 60 consecutive CT-guided cryoablation sessions targeting 95 pulmonary tumors in 47 patients from 2017 to 2020. The final thaw of a triple-freeze protocol was active (electrical, helium-free) in 27/60 sessions (45%, active group) and passive in 33/60 sessions (55%, passive group). Incidence, onset, and management of hemoptysis were recorded using prospectively collected data. Hemoptysis, pneumothorax, and hemothorax within 30 days post ablation were graded per Common Terminology Criteria for Adverse Events version 5.0 (CTCAE). Volume of immediate post-treatment changes on CT was quantified using semi-automated segmentation. Outcomes were compared between groups using generalized estimating equation models. A parsimonious multivariable model for hemoptysis incidence was developed using purposeful selection of predefined covariates followed by bootstrap resampling. Local tumor control was compared between groups using the Kaplan-Meier method and logrank testing. Results: Hemoptysis occurred following 26/60 (43%) sessions and was self-limited (Grade 1) in 22/26 (85%). The incidence of hemoptysis was lower in the active than passive group (64% vs 19%, respectively; p=.002). The odds of hemoptysis adjusted for immediate post-treatment changes were 92% lower in the active group (OR, 0.08 [95% CI, 0.02-0.37], p=.004). The odds of hemoptysis greater than Grade 1 were 79% lower in the active group (OR, 0.21 [95% CI, 0.07-0.64], p=.006). In the active group, the onset of hemoptysis was significantly delayed (OR, 0.75 [95% CI, 0.61-0.91], p=.005). Pneumothorax (p=.60), hemothorax (p=.84), and local tumor control (p=.77) did not differ between groups. Conclusion: Active thaw following the final freeze reduces the incidence and grade of hemoptysis and delays the onset of hemoptysis following percutaneous cryoablation of pulmonary tumors without adversely affecting other procedural complications and local tumor control. Clinical Impact: Active thaw following the final freeze improves the safety profile of triple-freeze cryoablation of pulmonary tumors by reducing the incidence and grade of hemoptysis and by delaying the onset of hemoptysis beyond the immediate recovery period.

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.