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Bronchial Thermoplasty (BT) is an endoscopic treatment for moderate-to-severe asthma patients who are uncontrolled despite optimal medical therapy. Effectiveness of BT has been demonstrated in several randomized clinical trials. However, the asthma phenotype that benefits most of this treatment is unclear, partly because the mechanism of action is incompletely understood. BT was designed to reduce the amount of airway smooth muscle (ASM), but additional direct and indirect effects on airway pathophysiology are expected. This review will provide an overview of the different components of airway pathophysiology including remodeling, with the ASM as the key player. Current concepts in the understanding of BT clinical effectiveness with a focus on its impact on airway remodeling will be reviewed.

Background: Bronchial thermoplasty (BT) is a novel treatment for severe asthma based on radiofrequency energy delivery to the larger airways. Although impressive radiological abnormalities have been reported, the incidence, pattern, and behavior over time of acute radiological abnormalities following BT are not well established. Objective: To assess the incidence pattern and behavior over time of acute radiological abnormalities following BT. Methods: This is a prospective, observational imaging study of severe asthma patients participating in the TASMA trial. Imaging of the lung (chest X-ray and/or computed tomography [CT]) was performed routinely before and directly after BT, within 6 weeks and at 6 months' follow-up. Results: Thirty-four chest X-rays were performed within <5 h following 34 BT procedures in 12 patients. In 91% of cases, radiological abnormalities were seen, designated as peribronchial consolidations (97%) and/or atelectasis (29%). Ultra-low-dose (ULD) chest CTs were performed following 16 BT procedures showing abnormalities in all. Four different radiological patterns were identified: peribronchial consolidations with surrounding ground glass opacities (94%), atelectasis (38%), partial bronchial occlusions (63%), and bronchial dilatations (19%). No bronchoscopic intervention was needed. At 6 months' follow-up, in a single patient, high-resolution chest CT showed a focal bronchiectasis in a single airway. Conclusions: There is a high incidence of acute radiological abnormalities after BT. Four distinct radiological patterns can be identified on ULD chest CT, which resolve without clinical impact in virtually all cases.

Although investigational at the moment, OCT and CLE are promising innovative high-resolution optical imaging techniques for the airway wall, lung parenchyma, mediastinal lymph nodes, and pulmonary vasculature. Clinical applications might contribute to improved disease identification and quantification, guidance for interventions/biopsies, and patient selection for treatments. Development of validated identification and quantification image-analysis systems is key for the future application of these imaging techniques in pulmonary medicine.