title: A hybrid method for airway segmentation and automated measurement of bronchial wall thickness on CT.
abstract: Inflammatory and infectious lung diseases commonly involve bronchial airway structures and morphology, and these abnormalities are often analyzed non-invasively through high resolution computed tomography (CT) scans. Assessing airway wall surfaces and the lumen are of great importance for diagnosing pulmonary diseases. However, obtaining high accuracy from a complete 3-D airway tree structure can be quite challenging. The airway tree structure has spiculated shapes with multiple branches and bifurcation points as opposed to solid single organ or tumor segmentation tasks in other applications, hence, it is complex for manual segmentation as compared with other tasks. For computerized methods, a fundamental challenge in airway tree segmentation is the highly variable intensity levels in the lumen area, which often causes a segmentation method to leak into adjacent lung parenchyma through blurred airway walls or soft boundaries. Moreover, outer wall definition can be difficult due to similar intensities of the airway walls and nearby structures such as vessels. In this paper, we propose a computational framework to accurately quantify airways through (i) a novel hybrid approach for precise segmentation of the lumen, and (ii) two novel methods (a spatially constrained Markov random walk method (pseudo 3-D) and a relative fuzzy connectedness method (3-D)) to estimate the airway wall thickness. We evaluate the performance of our proposed methods in comparison with mostly used algorithms using human chest CT images. Our results demonstrate that, on publicly available data sets and using standard evaluation criteria, the proposed airway segmentation method is accurate and efficient as compared with the state-of-the-art methods, and the airway wall estimation algorithms identified the inner and outer airway surfaces more accurately than the most widely applied methods, namely full width at half maximum and phase congruency.
authors.affiliation: Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Science Department, National Institutes of Health (NIH), Bethesda, MD 20892, United States.
authors.forename: Ziyue
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Center for Research in Computer Vision (CRCV), Department of Computer Science, University of Central Florida (UCF), Orlando, FL 32816, United States. Electronic address: ulasbagci@gmail.com.
authors.forename: Ulas
authors.initials: U
authors.lastname: Bagci
authors.affiliation: Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Science Department, National Institutes of Health (NIH), Bethesda, MD 20892, United States.
authors.forename: Brent
authors.initials: B
authors.lastname: Foster
authors.affiliation: Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Science Department, National Institutes of Health (NIH), Bethesda, MD 20892, United States.
authors.forename: Awais
authors.initials: A
authors.lastname: Mansoor
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, United States.
authors.forename: Jayaram K
authors.initials: JK
authors.lastname: Udupa
authors.affiliation: Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Science Department, National Institutes of Health (NIH), Bethesda, MD 20892, United States.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Mollura
mesh_terms: D000465:Algorithms; D001995:Bronchography / Q000379:methods*; D017143:Fuzzy Logic; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D000069550:Machine Learning; D010363:Pattern Recognition, Automated / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Airway wall thickness estimation; Full width at half maximum; Fuzzy connectedness; Phase congruency; Random walk