Mobile 3-dimensional (3D) C-arm system-assisted transbronchial biopsy and ablation for ground-glass opacity pulmonary nodules: a case report

Review on endobronchial therapies-current status and future

There is a growing demand for lung parenchymal-sparing localized therapies due to the rising incidence of multifocal lung cancers and the growing number of patients who cannot undergo surgery. Lung cancer screening has led to the discovery of more pre-malignant or early-stage lung cancers, and the focus has shifted from treatment to prevention. Transbronchial therapy is an important tool in the local treatment of lung cancers, with microwave ablation showing promise based on early and mid-term results. To improve the precision and efficiency of transbronchial ablation, adjuncts such as mobile C-arm platforms, software to correct for computed tomography (CT)-to-body divergence, metal-containing nanoparticles, and robotic bronchoscopy are useful. Other forms of energy such as steam vapor therapy, pulsed electric field, and photodynamic therapy are being intensively investigated. In addition, the future of transbronchial therapies may involve the intratumoral injection of novel agents such as immunomodulating agents, gene therapies, and chimeric antigen receptor T cells. Extensive pre-clinical and some clinical research has shown the synergistic abscopal effect of combination of these agents with ablation. This article aims to provide the latest updates on these technologies and explore their most likely future applications.

Virtual bronchoscopic navigation with intraoperative cone-beam CT for the diagnosis of peripheral pulmonary nodules

OBJECTIVE

Transbronchial biopsy is a safe manner with fewer complications than percutaneous transthoracic needle biopsy; however, the current diagnostic yield is still necessitating further improvement. We aimed to evaluate the diagnostic yield of using virtual bronchoscopic navigation (VBN) and cone-beam CT (CBCT) for transbronchial biopsy and to investigate the factors that affected the diagnostic sensitivity.

METHODS

We retrospectively investigated 255 patients who underwent VBN-CBCT-guided transbronchial biopsy at our two centers from May 2021 to April 2022. A total of 228 patients with final diagnoses were studied. Patient characteristics including lesion size, lesion location, presence of bronchus sign, lesion type and imaging tool used were collected and analyzed. Diagnostic yield was reported overall and in groups using different imaging tools.

RESULTS

The median size of lesion was 21 mm (range of 15.5-29 mm) with 46.1% less than 2 cm in diameter. Bronchus sign was present in 87.7% of the patients. The overall diagnostic yield was 82.1%, and sensitivity for malignancy was 66.3%. Patients with lesion > 2 cm or with bronchus sign were shown to have a significantly higher diagnostic yield. Four patients had bleeding and no pneumothorax occurred.

CONCLUSION

Guided bronchoscopy with VBN and CBCT was an effective diagnostic method and was associated with a high diagnostic yield in a safe manner. In addition, the multivariant analysis suggested that lesion size and presence of bronchus sign could be a predictive factor for successful bronchoscopic diagnosis.

Chinese expert consensus on cone-beam CT-guided diagnosis, localization and treatment for pulmonary nodules

Cone-beam computed tomography (CBCT) system can provide real-time 3D images and fluoroscopy images of the region of interest during the operation. Some systems can even offer augmented fluoroscopy and puncture guidance. The use of CBCT for interventional pulmonary procedures has grown significantly in recent years, and numerous clinical studies have confirmed the technology's efficacy and safety in the diagnosis, localization, and treatment of pulmonary nodules. In order to optimize and standardize the technical specifications of CBCT and guide its application in clinical practice, the consensus statement has been organized and written in a collaborative effort by the Professional Committee on Interventional Pulmonology of China Association for Promotion of Health Science and Technology.

Mobile Cone-Beam CT-Assisted Bronchoscopy for Peripheral Lung Lesions

Peripheral bronchoscopy with the use of thin/ultrathin bronchoscopes and radial-probe endobronchial ultrasound (RP-EBUS) has been associated with a fair diagnostic yield. Mobile cone-beam CT (m-CBCT) could potentially improve the performance of these readily available technologies. We retrospectively reviewed the records of patients undergoing bronchoscopy for peripheral lung lesions with thin/ultrathin scope, RP-EBUS, and m-CBCT guidance. We studied the performance (diagnostic yield and sensitivity for malignancy) and safety (complications, radiation exposure) of this combined approach. A total of 51 patients were studied. The mean target size was 2.6 cm (SD, 1.3 cm) and the mean distance to the pleura was 1.5 cm (SD, 1.4 cm). The diagnostic yield was 78.4% (95 CI, 67.1-89.7%), and the sensitivity for malignancy was 77.4% (95 CI, 62.7-92.1%). The only complication was one pneumothorax. The median fluoroscopy time was 11.2 min (range, 2.9-42.1) and the median number of CT spins was 1 (range, 1-5). The mean Dose Area Product from the total exposure was 41.92 Gy·cm² (SD, 11.35 Gy·cm²). Mobile CBCT guidance may increase the performance of thin/ultrathin bronchoscopy for peripheral lung lesions in a safe manner. Further prospective studies are needed to corroborate these findings.

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.

3D-2D image registration in the presence of soft-tissue deformation in image-guided transbronchial interventions

Purpose. Target localization in pulmonary interventions (e.g. transbronchial biopsy of a lung nodule) is challenged by deformable motion and may benefit from fluoroscopic overlay of the target to provide accurate guidance. We present and evaluate a 3D-2D image registration method for fluoroscopic overlay in the presence of tissue deformation using a multi-resolution/multi-scale (MRMS) framework with an objective function that drives registration primarily by soft-tissue image gradients.Methods. The MRMS method registers 3D cone-beam CT to 2D fluoroscopy without gating of respiratory phase by coarse-to-fine resampling and global-to-local rescaling about target regions-of-interest. A variation of the gradient orientation (GO) similarity metric (denotedGO') was developed to downweight bone gradients and drive registration via soft-tissue gradients. Performance was evaluated in terms of projection distance error at isocenter (PDE_iso). Phantom studies determined nominal algorithm parameters and capture range. Preclinical studies used a freshly deceased, ventilated porcine specimen to evaluate performance in the presence of real tissue deformation and a broad range of 3D-2D image mismatch.Results. Nominal algorithm parameters were identified that provided robust performance over a broad range of motion (0-20 mm), including an adaptive parameter selection technique to accommodate unknown mismatch in respiratory phase. TheGO'metric yielded median PDE_iso= 1.2 mm, compared to 6.2 mm for conventionalGO.Preclinical studies with real lung deformation demonstrated median PDE_iso= 1.3 mm with MRMS +GO'registration, compared to 2.2 mm with a conventional transform. Runtime was 26 s and can be reduced to 2.5 s given a prior registration within ∼5 mm as initialization.Conclusions. MRMS registration via soft-tissue gradients achieved accurate fluoroscopic overlay in the presence of deformable lung motion. By driving registration via soft-tissue image gradients, the method avoided false local minima presented by bones and was robust to a wide range of motion magnitude.

Sintilimab for the treatment of non-small cell lung cancer

Anti-programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) immunotherapy has dramatically changed the therapeutic landscape of inoperable non-small cell lung cancer (NSCLC), and has been included in first-line treatments. Sintilimab is a domestic anti-PD-1 monoclonal antibody in China that has received approvals from the National Medical Products Administration to treat classical Hodgkin’s lymphoma, hepatocellular carcinoma, and squamous and non-squamous NSCLC. In a prospective clinical study we led, neoadjuvant sintilimab has led to major and complete pathologic responses, which are recommended as surrogate endpoints for neoadjuvant immunotherapy; however, its effect remains inconclusive in pulmonary ground glass nodules. Meanwhile, combination plans seem more likely to be satisfying therapeutic options. Specifically, sintilimab plus platinum-based chemotherapy plans conferred better anti-tumor efficacy and clinical benefits compared to chemotherapy alone, which led to their approval in China and the acceptance of a biological license application in the US. Besides, the combination with other plans, such as docetaxel, cytokine-induced killer cell immunotherapy, radiation therapy, and anlotinib have also shown promising anti-tumor efficacy, with acceptable toxicities, and are therefore worth further exploration. In addition, several clinical trials on NSCLC at our center are ongoing. In general, sintilimab and its combinatorial plans were effective and well tolerated, but the treatment requires appropriate timing; pathologic responses can be surrogate endpoints for neoadjuvant immunotherapy, while more effective biomarkers are warranted. This study provides an overview of sintilimab-based clinical trials on NSCLC, and may support further investigation of sintilimab in future clinical trials.

Robotic bronchoscopy and future directions of interventional pulmonology

PURPOSE OF REVIEW

To describe the emerging field of robotic bronchoscopy within advanced diagnostic bronchoscopy. We review the literature available for these two novel platforms to highlight their differences and discuss the impact on future directions.

RECENT FINDINGS

There are two distinct technologies both known as robotic bronchoscopy. The Monarch robotic-assisted bronchoscopy is based on electromagnetic guidance whereas the Ion robotic-assisted bronchoscopy is founded on shape sensing technology. Although there is ongoing work to explore the capabilities of these systems, studies have shown that both are safe modalities. Furthermore, both hold promise to improve diagnostic yield and may eventually pave the way for therapeutic bronchoscopic ablation in the future.

SUMMARY

Although both platforms fall under the umbrella term of robotic-assisted bronchoscopy, the Monarch and Ion systems are quite unique in their technology. Thus far, both have demonstrated safety, and early data shows promising results for improved diagnostic yield compared to previously advanced bronchoscopy modalities, especially when combined with advanced confirmatory imaging. Future directions may include bronchoscopic ablation of peripheral lesions given the stability and reach of these platforms.