Development and Analysis of Patient-Based Complete Conducting Airways Models

• Published in: PloS one Vol. 10; no. 12; p. e0144105
• Main Authors: Bordas, Rafel, Lefevre, Christophe, Veeckmans, Bart, Pitt-Francis, Joe, Fetita, Catalin, Brightling, Christopher E., Kay, David, Siddiqui, Salman, Burrowes, Kelly S.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11.12.2015; Public Library of Science (PLoS)
• Subjects: Aged; Airway Resistance; Algorithms; Asthma; Biology; Biomedical engineering; CAT scans; Chronic obstructive lung disease; Chronic obstructive pulmonary disease; Computed tomography; Computer applications; Computer science; Data processing; Diagnosis; Engineering; Engineering Sciences; Female; Flow rates; Flow resistance; High resolution; Humans; Image analysis; Image processing; Image resolution; Low flow; Lung - anatomy & histology; Lung - diagnostic imaging; Lung - physiology; Lung diseases; Lungs; Male; Mathematical models; Middle Aged; Models, Anatomic; Numerical analysis; Obstructive lung disease; Patients; Physiology; Respiration; Respiratory function; Respiratory tract diseases; Signal and Image processing; Studies; Tomography, X-Ray Computed; Ventilators; France; United Kingdom; United Kingdom > UK
• DOI: 10.1371/journal.pone.0144105
• ISSN: 1932-6203

The analysis of high-resolution computed tomography (CT) images of the lung is dependent on inter-subject differences in airway geometry. The application of computational models in understanding the significance of these differences has previously been shown to be a useful tool in biomedical research. Studies using image-based geometries alone are limited to the analysis of the central airways, down to generation 6-10, as other airways are not visible on high-resolution CT. However, airways distal to this, often termed the small airways, are known to play a crucial role in common airway diseases such as asthma and chronic obstructive pulmonary disease (COPD). Other studies have incorporated an algorithmic approach to extrapolate CT segmented airways in order to obtain a complete conducting airway tree down to the level of the acinus. These models have typically been used for mechanistic studies, but also have the potential to be used in a patient-specific setting. In the current study, an image analysis and modelling pipeline was developed and applied to a number of healthy (n = 11) and asthmatic (n = 24) CT patient scans to produce complete patient-based airway models to the acinar level (mean terminal generation 15.8 ± 0.47). The resulting models are analysed in terms of morphometric properties and seen to be consistent with previous work. A number of global clinical lung function measures are compared to resistance predictions in the models to assess their suitability for use in a patient-specific setting. We show a significant difference (p < 0.01) in airways resistance at all tested flow rates in complete airway trees built using CT data from severe asthmatics (GINA 3-5) versus healthy subjects. Further, model predictions of airways resistance at all flow rates are shown to correlate with patient forced expiratory volume in one second (FEV1) (Spearman ρ = -0.65, p < 0.001) and, at low flow rates (0.00017 L/s), FEV1 over forced vital capacity (FEV1/FVC) (ρ = -0.58, p < 0.001). We conclude that the pipeline and anatomical models can be used directly in mechanistic modelling studies and can form the basis for future patient-based modelling studies.