Robert C. Gilkeson, MD

Abstract: A significant advance in CT imaging is the use of 3-dimensional (3D) reconstruction techniques. A 3D reconstruction, for example, permits a volumetric evaluation of the contours of the airways and displays areas of stricture, or narrowing, more effectively than do routine axial images. External 3D rendering, also called CT bronchography, helps reveal complex airway abnormalities and improves the detection of subtle airway stenoses. Although it is primarily an investigational tool, internal 3D rendering (virtual bronchoscopy) has several potential applications, including assessing airway stenoses, guiding transbronchial biopsy procedures, and screening for lung cancer. Multiplanar reformation imaging methods can aid in the assessment of airway stenoses, airway stents, tracheomalacia, and extrinsic airway compression. A review of multiplanar images can also aid in the planning of stent placement or surgery. (J Respir Dis. 2006;27(8):348-352)

Abstract: Advances in CT technology afford the ability to create 3-dimensional (3-D) reconstructions of the airways in only a few minutes. The 2 basic types of 3-D reconstruction imaging methods are CT bronchography, which depicts the external surface of the airways and its relationship to adjacent structures, and virtual bronchoscopy, which allows the viewer to navigate the internal lumen of the airways by a means similar to conventional bronchoscopy. Although axial images are routinely used to evaluate the upper airways, multiplanar reformations in the coronal and sagittal planes also help evaluate upper airway pathology. Coronal multiplanar reformation images are useful in defining the anatomy of the larynx; sagittal images provide excellent delineation of the epiglottis, vallecula, and piriform sinuses. Axial images are the reference standard for assessing tracheal wall thickening and, therefore, may be particularly helpful in the differential diagnosis of tracheal stenosis. (J Respir Dis. 2006;27(6):266-273)

Abstract: The introduction of helical CT dramatically improved the quality of CT images of the airways and other thoracic structures. Multi-detector row CT scanners have made further improvements with respect to spatial resolution, speed, and anatomic coverage. Axial CT images provide valuable information about the airway lumen and wall and adjacent mediastinal and lung structures, but they are limited in their ability to assess airway stenoses and complex airway abnormalities. These limitations can be overcome by multiplanar and 3-dimensional reconstruction images. State-of-the-art scanners allow all of the central airways to be imaged in a few seconds. This speed is particularly valuable for patients who cannot tolerate longer breath-holds and patients who may have tracheomalacia or vocal cord paralysis. (J Respir Dis. 2006;27(5):192-196)