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

Pre-operative lung ablation prediction using deep learning

OBJECTIVE

Microwave lung ablation (MWA) is a minimally invasive and inexpensive alternative cancer treatment for patients who are not candidates for surgery/radiotherapy. However, a major challenge for MWA is its relatively high tumor recurrence rates, due to incomplete treatment as a result of inaccurate planning. We introduce a patient-specific, deep-learning model to accurately predict post-treatment ablation zones to aid planning and enable effective treatments.

MATERIALS AND METHODS

Our IRB-approved retrospective study consisted of ablations with a single applicator/burn/vendor between 01/2015 and 01/2019. The input data included pre-procedure computerized tomography (CT), ablation power/time, and applicator position. The ground truth ablation zone was segmented from follow-up CT post-treatment. Novel deformable image registration optimized for ablation scans and an applicator-centric co-ordinate system for data analysis were applied. Our prediction model was based on the U-net architecture. The registrations were evaluated using target registration error (TRE) and predictions using Bland-Altman plots, Dice co-efficient, precision, and recall, compared against the applicator vendor's estimates.

RESULTS

The data included 113 unique ablations from 72 patients (median age 57, interquartile range (IQR) (49-67); 41 women). We obtained a TRE ≤ 2 mm on 52 ablations. Our prediction had no bias from ground truth ablation volumes (p = 0.169) unlike the vendor's estimate (p < 0.001) and had smaller limits of agreement (p < 0.001). An 11% improvement was achieved in the Dice score. The ability to account for patient-specific in-vivo anatomical effects due to vessels, chest wall, heart, lung boundaries, and fissures was shown.

CONCLUSIONS

We demonstrated a patient-specific deep-learning model to predict the ablation treatment effect prior to the procedure, with the potential for improved planning, achieving complete treatments, and reduce tumor recurrence.

CLINICAL RELEVANCE STATEMENT

Our method addresses the current lack of reliable tools to estimate ablation extents, required for ensuring successful ablation treatments. The potential clinical implications include improved treatment planning, ensuring complete treatments, and reducing tumor recurrence.

Retrospective cohort study on the correlation analysis among peri-procedural factors, complications, and local tumor progression of lung tumors treated with CT-guided microwave ablation

Background

Despite adherence to guidelines, recurrence of lesions remains possible in lung tumor microwave ablation (MWA) even when termination is enabled by 5-10 mm ground glass changes. Limited evidence exists regarding the correlation between timely management of perioperative complications (including pneumothorax, pleural effusion, hemorrhage, cavity formation, and infection) and local tumor progression. This retrospective study aimed to investigate the relationship among peri-procedural factors, complications, and local tumor progression in 164 cases of lung tumors treated with computed tomography-guided MWA (CT-MWA), and improve the local prognosis and reduce the complication rate of CT-guided lung tumor ablation.

Methods

We reviewed 164 consecutive patients who underwent CT-MWA at Fudan University Shanghai Cancer Center's Minimally Invasive Therapy Center for lung cancer from September 2019 to May 2020. Correlative analysis was performed between peri-procedural factors, complications and outcomes (local tumor progression rates). Patients who have had prior surgery or previous MWA were excluded. Ablation was the first treatment of choice, and all patients who have had other treatments were excluded. Patients were followed every 3 months with CT. Outcomes of ablation including complications and local tumor progression were evaluated. Peri-procedural factors included demographical factors, tumor features, ablation parameters, management of intra-procedural pneumothorax, and CT features. Complications included pneumothorax, post-procedural refractory infection, and pleural effusion.

Results

The study included 98 males and 68 females, with an average age of 56.1 years. Local tumor progression rate was negatively correlated with intra-procedural management of pneumothorax (R=-0.550, P=0.0003) and Hounsfield unit (HU) difference between HU before and after procedure (R=-0.855, P=0.006), and positively correlated with the average HU value of immediate post-procedural CT at the measurement points (R=0.857, P=0.00002). The correlation analysis results also showed a positive correlation between infection after procedure and pneumothorax (R=0.340, P=0.0001).

Conclusions

A greater difference between HU before and after the procedure or a decrease in CT values immediately after ablation may predict a higher rate of local complete ablation. Prompt management of intraoperative pneumothorax may lower local tumor progression rates and decrease incidence of post-procedural infection.

Simultaneous percutaneous microwave ablation and biopsy for highly suspected malignant pulmonary nodules: a retrospective cohort study

Background

The conventional diagnosis and treatment for highly suspected malignant pulmonary nodules (PNs) can avoid unnecessary treatment to some extent. However, the relatively separate puncture processes may not only increase puncture-related complications, but also increase the patient's radiation exposure and hospitalization costs. The purpose of this study was to retrospectively analyze the effectiveness of simultaneous percutaneous microwave ablation (MWA) and percutaneous biopsy (PB) for PNs.

Methods

From August 2015 to August 2022, 65 consecutive patients [48 solid nodules, 6 ground glass opacities (GGOs), 11 mixed nodules] with suspected single malignant PN underwent MWA and PB combination treatments at the First Affiliated Hospital of Zhengzhou University. The total of 30 patients in Group A underwent synchronous PB and MWA (strategy: low-power MWA-PB-high-power MWA), whereas 35 patients in Group B underwent asynchronous PB and MWA. The technical success, complete ablation (CA), complications, total procedure time (TPT), patient exposure dose (PED), hospitalization time, and costs were compared. An independent samples t-, χ2, or Fisher's exact tests were used.

Results

The technical success (100% vs. 100%) and CA (100% vs. 97.1%) rates were not significantly different between Groups A and B. The complications of intrapulmonary hemorrhage (16.7% vs. 41.4%, P=0.02) and hemoptysis (0% vs. 8.6%, P=0.04) were significantly different between Groups A and B. TPT (41.6±7.9 vs. 57.3±8.8 min, P<0.001), PED (12.9±1.4 vs. 19.4±2.3 mSv, P<0.001), hospitalization stay (4.7±1.3 vs. 9.1±2.1 days, P<0.001) and costs (3,768.8±652.9 vs. 4,508.0±514.1 USD, P<0.001) also showed significant differences between Groups A and B.

Conclusions

Synchronous PB and MWA for PNs is a safe and effective strategy that can decrease bleeding, PED, the hospitalization stay, and costs.

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.

Safety and efficacy of microwave ablation for lung cancer adjacent to the interlobar fissure

Background

This retrospective study aimed to assess the safety and efficacy of microwave ablation for lung tumors adjacent to the interlobar fissures.

Methods

From May 2020 to April 2021, 59 patients with 66 lung tumors (mean diameter, 16.9 ± 7.7 mm; range, 6–30 mm) adjacent to the interlobar fissures who underwent microwave ablation at our institution were identified and included in this study. Based on the relationship between the tumor and the interlobar fissure, tumors can be categorized into close to the fissure, causing the fissure, and involving the fissure. The complete ablation rate, local progression‐free survival, complications, and associated factors were analyzed.

Results

All 66 histologically proven tumors were treated using computed tomography‐guided microwave ablation. The complete ablation rate was 95.5%. Local progression‐free survival at 3, 6, 9, and 12 months were 89.4%, 83.3%, 74.2%, and 63.6%, respectively. The complications included pneumothorax (34.8%), pleural effusion (24.2%), cavity (18.2%), and pulmonary infection (7.6%). There were statistical differences in the incidence of pneumothorax, cavity, and delayed complications between the groups with and without antenna punctures through the fissure.

Conclusions

Microwave ablation is a safe and effective treatment for lung tumor adjacent to the interlobar fissure. Antenna puncturing though the interlobar fissure may be a potential risk factor for pneumothorax, cavity, and delayed complications.

Ablation techniques in non-small cell lung cancer patients: experience of a single center

BACKGROUND

Percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) are well-established treatments for patients with non-small cell lung cancer (NSCLC). This study assessed the efficacy and safety of RFA and MWA performed on NSCLC patients.

MATERIAL AND METHODS

This retrospective study included one hundred twenty-four patients with NSCLC who underwent percutaneous ablation from November 2014 to November 2020 in the Department of Medical Imaging and Interventional Radiology of Sotiria General Hospital for Chest Diseases in Athens, Greece. Forty (stage IA) were treated with RFA, while 84 were treated with MWA (stages IA, IB, and IIA). All procedures were performed using the AMICA GEN radiofrequency and microwave generator. As a follow-up method, computed tomography was performed immediately after the procedure to evaluate the lesion's response and complications and one, three, six, and twelve months after the ablation.

RESULTS

All ablations were technically successful. The first-month follow-up revealed stage IIA residual tumors in eight patients. Local recurrence was detected one year after RFA in two of the 40 patients and thirteen of the 84 patients after MWA. Overall survival (OS) rates at one, two, and three years for stage IA NSCLC patients treated with ablation were 94 %, 73 %, 57 % for RFA, and 96 %, 75 %, and 62 % for MWA, respectively. In contrast, the OS for stages IB and IIA patients treated with MWA was 90 %, 66 %, and 51 % for the IB stage and 82 %, 62 %, and 48 % for the IIA stage, respectively. Fifteen percent of patients after RFA and 9.5 % after MWA experienced minor complications. Pneumothorax was documented in three patients after RFA and four after MWA. Post-ablation syndrome occurred in 15 % of RFA patients and 8.3 % of MWA patients. There were no major complications.

CONCLUSION

RFA and MWA have comparable efficacy and safety for patients in stage IA. MWA is an effective alternative treatment option for non-resectable IB or IIA stages NSCLC patients. HIPPOKRATIA 2022, 26 (3):105-109.