title: Eliminating rib shadows in chest radiographic images providing diagnostic assistance.
abstract: A major difficulty with chest radiographic analysis is the invisibility of abnormalities caused by the superimposition of normal anatomical structures, such as ribs, over the main tissue to be examined. Suppressing the ribs with no information loss about the original tissue would therefore be helpful during manual identification or computer-aided detection of nodules on a chest radiographic image. In this study, we introduce a two-step algorithm for eliminating rib shadows in chest radiographic images. The algorithm first delineates the ribs using a novel hybrid self-template approach and then suppresses these delineated ribs using an unsupervised regression model that takes into account the change in proximal thickness (depth) of bone in the vertical axis. The performance of the system is evaluated using a benchmark set of real chest radiographic images. The experimental results determine that proposed method for rib delineation can provide higher accuracy than existing methods. The knowledge of rib delineation can remarkably improve the nodule detection performance of a current computer-aided diagnosis (CAD) system. It is also shown that the rib suppression algorithm can increase the nodule visibility by eliminating rib shadows while mostly preserving the nodule intensity.
authors.affiliation: Department of Computer Engineering, Başkent University, Ankara, Turkey. Electronic address: hogul@baskent.edu.tr.
authors.forename: Hasan
authors.initials: H
authors.lastname: Oğul
authors.affiliation: Akgun Software Company, Ankara, Turkey.
authors.forename: B Buket
authors.initials: BB
authors.lastname: Oğul
authors.affiliation: Department of Radiology, Faculty of Medicine, Başkent University, Ankara, Turkey.
authors.forename: A Muhteşem
authors.initials: AM
authors.lastname: Ağıldere
authors.affiliation: Department of Computer Engineering, Başkent University, Ankara, Turkey; Medicines and Medical Devices Agency of Turkey, Ankara, Turkey.
authors.forename: Tuncay
authors.initials: T
authors.lastname: Bayrak
authors.affiliation: Department of Computer Engineering, Başkent University, Ankara, Turkey.
authors.forename: Emre
authors.initials: E
authors.lastname: Sümer
mesh_terms: D003936:Diagnosis, Computer-Assisted; D006801:Humans; D013902:Radiography, Thoracic / Q000379:methods*; D012272:Ribs
keywords: Bone suppression; Chest radiography; Computer-aided diagnosis (CAD); Medical image analysis