Grading remodeling severity in asthma based on airway wall thickening index and bronchoarterial ratio measured with MSCT

Defining therapeutic protocols in asthma and monitoring patient response require a more in-depth knowledge on the disease severity and treatment outcome based on quantitative indicators. This paper aims at grading severity in asthma based on objective morphological measurements obtained in automated fashion from 3-D multi-slice computed tomography (MSCT) image datasets. These measures attempt to capture and quantify the airway remodeling process involved in asthma, both at the level of the airway wall thickness and airway lumen. Two morphological changes are thus targeted here, (1) the airway wall thickening measured as a global index characterizing the increase of wall thickness above a normal value of wall-to-lumen-radius ratio, and (2) the bronchoarterial ratio index assessed globally from numerous locations in the lungs. The combination of these indices provides a grading of the severity of the remodeling process in asthma which correlates with the known phenotype of the patients investigated. Preliminary application to assess the patient response in thermoplasty trials is also considered from the point of view of the defined indices.