VIRTUAL BRONCHOSCOPY FOR 3-DIMENSIONAL PULMONARY IMAGE ASSESSMENT - STATE-OF-THE-ART AND FUTURE-NEEDS

Virtual bronchoscopy is emerging as a useful approach for assessment o f three-dimensional OD) computed tomographic (CT) pulmonary images. A protocol for virtual bronchoscopic assessment of a 3D CT pulmonary ima ge would have two main stages: (a) preprocessing of image data, which involves extracting objects of interest, defining paths through major airways, and preparing the extracted objects for 3D rendering; and (b) interactive image assessment, which involves use of graphics-based so ftware tools such as surface-rendered views, projection images, virtua l endoscopic views, tube views, oblique section images, measurement da ta, global two-dimensional section images, and cross-sectional views. Although a virtual bronchoscope offers a unique opportunity for explor ation and quantitation, it cannot replace a real bronchoscope. Limitat ions of current virtual endoscopy systems include high cost, lack of v isual aids beyond simulated endoscopic views, difficulty in performing interactive anatomic exploration, lack of quantitative information, u se of surface rendering instead of volume rendering, and need for subs tantial off-line display computation. Future needs include development of fully integrated user-friendly virtual bronchoscopes, development of optimal CT protocols for generating artifact-free data sets, and im provements in automated preprocessing of 3D CT images.