Multimodal imaging guidance for laser ablation in tracheal stenosis

The LMIT: Light-mediated minimally-invasive theranostics in oncology

Minimally-invasive diagnosis and therapy have gradually become the trend and research hotspot of current medical applications. The integration of intraoperative diagnosis and treatment is a development important direction for real-time detection, minimally-invasive diagnosis and therapy to reduce mortality and improve the quality of life of patients, so called minimally-invasive theranostics (MIT). Light is an important theranostic tool for the treatment of cancerous tissues. Light-mediated minimally-invasive theranostics (LMIT) is a novel evolutionary technology that integrates diagnosis and therapeutics for the less invasive treatment of diseased tissues. Intelligent theranostics would promote precision surgery based on the optical characterization of cancerous tissues. Furthermore, MIT also requires the assistance of smart medical devices or robots. And, optical multimodality lay a solid foundation for intelligent MIT. In this review, we summarize the important state-of-the-arts of optical MIT or LMIT in oncology. Multimodal optical image-guided intelligent treatment is another focus. Intraoperative imaging and real-time analysis-guided optical treatment are also systemically discussed. Finally, the potential challenges and future perspectives of intelligent optical MIT are discussed.

Tracheobronchial Surgery in Emerging Countries

Tracheobronchial surgery is widely performed in emerging countries mainly as a consequence of the high number of airway-related complications and poor management in intensive care units. This has led to great expertise in the surgical management of postintubation tracheal stenosis, and opportunity for advancing scientific knowledge. Nonetheless, tracheal stenosis has a severe impact on a patient's quality of life, is a major burden to the health system, and should be prevented. Incorporation of innovative techniques, technologies, and prospective databases should prompt earlier diagnosis and lead to fewer complications.

Antifibrotic Role of Nintedanib in Tracheal Stenosis After a Tracheal Wound

OBJECTIVES/HYPOTHESIS

Tracheal stenosis is an obstructive disease of the upper airway that commonly develops as a result of abnormal wound healing. We evaluated the anti-inflammatory and antifibrotic properties of nintedanib on tracheal stenosis both in vitro and in vivo.

STUDY DESIGN

Prospective controlled animal study and in vitro comparative study of human cells.

METHODS

An animal model of tracheal stenosis was induced via tracheal trauma. Postsurgical rats were orally administered with nintedanib (10 or 20 mg/kg/d) or saline (negative control) for 2 weeks, and tracheal specimens were harvested after 3 weeks. Degree of stenosis, collagen deposition, fibrotic surrogate markers expression, and T-lymphocytic infiltration were evaluated. Human fetal lung fibroblast-1 (HFL-1) cells were cultured to determine the effects of nintedanib on changes of cellular biological function induced by transforming growth factor-β1 (TGF-β1).

RESULTS

Rat tracheal stenotic tissues exhibited thickened lamina propria with irregular epithelium, characterized by significantly increased collagen deposition and elevated TGF-β1, collagen I, α-SMA and fibronectin expressions. Nintedanib markedly attenuated the tracheal stenotic lesions, reduced the collagen deposition and the expression of fibrotic marker proteins, and mitigated CD4+ T-lymphocyte infiltration. Additionally, cellular proliferation and migration were decreased dose-dependently in TGF-β1-stimulated HFL-1 cells when treated with nintedanib. Furthermore, nintedanib inhibited TGF-β1-induced HFL-1 differentiation and reduced the mRNA levels of the profibrotic genes. TGF-β1-activated phosphorylation of the TGF-β/Smad2/3 and ERK1/2 pathways were also blocked by nintedanib.

CONCLUSION

Nintedanib effectively prevented tracheal stenosis in rats by inhibiting fibrosis and inflammation. The antifibrotic effect of nintedanib may be achieved by inhibiting fibroblasts' proliferation, migration and differentiation and suppressing the TGF-β1/Smad2/3 and ERK1/2 signaling pathways.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:E2496-E2505, 2021.

Interventional Pulmonology: Diagnostic and Therapeutic Advances in Bronchoscopy

BACKGROUND

Interventional pulmonology is a rapidly evolving subspecialty of pulmonary medicine that offers advanced consultative and procedural services to patients with airway diseases, pleural diseases, as well as in the diagnosis and management of patients with thoracic malignancy.

AREAS OF UNCERTAINTY

The institution of lung cancer screening modalities as well as the search of additional minimally invasive diagnostic and treatment modalities for lung cancer and other chronic lung diseases has led to an increased focus on the field of interventional pulmonology. Rapid advancements in the field over the last 2 decades has led to development of various new minimally invasive bronchoscopic approaches and techniques for patients with cancer as well as for patients with chronic lung diseases.

DATA SOURCES

A review of literature was performed using PubMed database to identify all articles published up till October 2020 relevant to the field of interventional pulmonology and bronchoscopy. The reference list of each article was searched to look for additional articles, and all relevant articles were included in the article.

THERAPEUTIC ADVANCES

Newer technologies are now available such navigation platforms to diagnose and possibly treat peripheral pulmonary nodules, endobronchial ultrasound in diagnosis of mediastinal and hilar adenopathy as well as cryobiopsy in the diagnosis of diffuse lung diseases. In addition, flexible and rigid bronchoscopy continues to provide new and expanding ability to manage patients with benign and malignant central airway obstruction. Interventions are also available for diseases such as asthma, chronic bronchitis, chronic obstructive pulmonary disease, and emphysema that were traditionally treated with medical management alone.

CONCLUSIONS

With continued high quality research and an increasing body of evidence, interventional bronchoscopy has enormous potential to provide both safe and effective options for patients with a variety of lung diseases.

A new endoscopic hand drill for management of tracheal stenosis

Tracheal resection and primary anastomosis is the treatment of choice for the management of benign tracheal stenoses. Rigid endoscopy with laser-assisted mechanical dilatation is an alternative to surgery and helps to improve symptoms and quality of life in patients unfit for surgery. Here, we describe the treatment of a simple web-like stenosis, using a new endoscopic hand drill that was assembled by sharpening the blunt tip of a standard endoscopic cotton applicator. The bronchoscopy was positioned proximally to the stenotic lesion and radial holes were made at 12, 3 and 9 o'clock. The tip of instrument touched the target area of the stenotic scar. The proximal end was handily rotated and the force, applied on the instrument's tip, and the hole was drilled. Next, endoscopic scissors was placed in the drill holes and the stenotic scar was cut. Mechanical dilatation with rigid bronchoscopes of increasing diameters completed the procedure. This procedure was successfully applied in 5 patients with simple benign tracheal stenosis and unfit for surgery. No intraoperative and/or postoperative complications occurred. No recurrence of stenosis was detected after a mean follow-up of 26 ± 2 months.

Past, present, and future of endobronchial laser photoresection

Laser photoresection of central airway obstruction is a useful tool for an Interventional Pulmonologist (IP). Endobronchial therapy of the malignant airway obstruction is considered as a palliative measure or a bridge therapy to the definite treatment of cancer. Several ablative therapies such as electrocautery, argon plasma coagulation (APC), cryotherapy and laser photoresection exist in the armamentarium of IP to tackle such presentations. Besides Neodymium-Yttrium, Aluminum, Garnet (Nd:YAG) laser, there are several different types of laser that have been used by the pulmonologist with different coagulative and cutting properties. This chapter focuses on the historical perspective, current status, and potentials of lasers in the management of central airway lesions.

Miniature forward-imaging B-scan optical coherence tomography probe to guide real-time laser ablation

BACKGROUND AND OBJECTIVE

Investigations have shown that pulsed lasers tuned to 6.1 µm in wavelength are capable of ablating ocular and neural tissue with minimal collateral damage. This study investigated whether a miniature B-scan forward-imaging optical coherence tomography (OCT) probe can be combined with the laser to provide real-time visual feedback during laser incisions.

STUDY DESIGN/METHODS AND MATERIALS

A miniature 25-gauge B-scan forward-imaging OCT probe was developed and combined with a 250 µm hollow-glass waveguide to permit delivery of 6.1 µm laser energy. A gelatin mixture and both porcine corneal and retinal tissues were simultaneously imaged and lased (6.1 µm, 10 Hz, 0.4-0.7 mJ) through air. The ablation studies were observed and recorded in real time. The crater dimensions were measured using OCT imaging software (Bioptigen, Durham, NC). Histological analysis was performed on the ocular tissues.

RESULTS

The combined miniature forward-imaging OCT and mid-infrared laser-delivery probe successfully imaged real-time tissue ablation in gelatin, corneal tissue, and retinal tissue. Application of a constant number of 60 pulses at 0.5 mJ/pulse to the gelatin resulted in a mean crater depth of 123 ± 15 µm. For the corneal tissue, there was a significant correlation between the number of pulses used and depth of the lased hole (Pearson correlation coefficient = 0.82; P = 0.0002). Histological analysis of the cornea and retina tissues showed discrete holes with minimal thermal damage.

CONCLUSIONS

A combined miniature OCT and laser-delivery probe can monitor real-time tissue laser ablation. With additional testing and improvements, this novel instrument has the future possibility of effectively guiding surgeries by simultaneously imaging and ablating tissue.

Optical coherence tomography in conjunction with bronchoscopy

OBJECTIVE

To evaluate the feasibility of and the potential for using optical coherence tomography in conjunction with conventional bronchoscopy in the evaluation of the airways.

METHODS

This was a pilot study based on an ex vivo experimental model involving three animals: one adult New Zealand rabbit and two Landrace pigs. An optical coherence tomography imaging catheter was inserted through the working channel of a flexible bronchoscope in order to reach the distal trachea of the animals. Images of the walls of the trachea were systematically taken along its entire length, from the distal to the proximal portion.

RESULTS

The imaging catheter was easily adapted to the working channel of the bronchoscope. High-resolution images of cross sections of the trachea were taken in real time, precisely delineating microstructures, such as the epithelium, submucosa, and cartilage, as well as the adventitia of the anterior and lateral tracheal walls. The corresponding layers of the epithelium, mucosa, and cartilage were clearly differentiated. The mucosa, submucosa, and trachealis muscle were clearly identified in the posterior wall.

CONCLUSIONS

It is feasible to use an optical coherence tomography imaging catheter in combination with a flexible bronchoscope. Optical coherence tomography produces high-resolution images that reveal the microanatomy of the trachea, including structures that are typically seen only on images produced by conventional histology.

Scientific evidence and principles for the use of endobronchial ultrasound and transbronchial needle aspiration

Endobronchial ultrasound (EBUS), using the radial EBUS probe and convex-probe EBUS-guided transbronchial needle aspiration, are increasingly advocated for a wide array of minimally invasive thoracic procedures. The effectiveness of EBUS-guided procedures has been demonstrated to a degree that, in many institutions, EBUS is becoming standard of practice for the diagnosis, staging and restaging of mediastinal lymphadenopathy in lung cancer, the diagnosis of sarcoidosis, and for bronchoscopic biopsy of peripheral lung lesions. Its role in other bronchoscopic procedures requires further study despite an already strong body of literature: diagnosis of lymphoma and benign infectious disease, diagnosis of early lung cancer and airway wall disorders, imaging of thoracic vascular disease such as pulmonary embolism, and therapeutic procedures such as placement of fiducial markers. In this article, we illustrate some of the principles of EBUS, describe major technical aspects pertaining to the procedure itself and provide a narrative review of original research addressing proposed roles of EBUS in a variety of indications. In closing, we describe future perspectives including new educational processes and philosophies that could favorably impact the rapid and safe dissemination of this evolving technology into clinical practice.

Recent advances in optical coherence tomography for the diagnoses of lung disorders

There have been many advances in the field of diagnostic and therapeutic pulmonary medicine in the past several years, with major progress in the field of imaging. Optical coherence tomography (OCT) is a high-resolution (micron level) imaging modality currently being advanced with the potential to image airway wall structures in real time and at higher resolution than previously possible. OCT has the potential to increase the sensitivity and specificity of biopsies, create 3D images of the airway to guide diagnostics, and may have a future role in diverse areas such as the evaluation and treatment of patients with obstructive sleep apnea, tracheal stenosis, airway remodeling and inhalation injury. OCT has recently been investigated to monitor airway compliance in chronic obstructive pulmonary disease and asthma patients as well as differentiate causes of pulmonary hypertension. In future clinical and research applications, OCT will likely be combined with other endoscopic based modalities such as ultrasound, spectroscopy, confocal, and/or photoacoustic tomography to determine functional and biomolecular properties. This article discusses the current uses of OCT, its potential applications, as it relates to specific pulmonary diseases, and the future directions for OCT.