During the 1990s, helical CT scanning revolutionized diagnostic imaging. Patients are imaged much faster, with a consequent decrease in radiation dosage and motion artifact.<sup>18 Vock P., Soucek M., Jeffrey R.B. , e al. Lung: Spiral volumetric CT with single-breath-hold technique Radiology 1990 ;  176 : 864-867

Cliccare qui per andare alla sezione Riferimenti</sup> In addition, because helical scanning acquires continuous images of a patient's body, it provides imaging data between the actual slices displayed. This complete data of a patient's body can be retrieved easily and reprocessed into additional images. Image reconstruction is routinely used to search for anatomic structures that are smaller than the CT scan slice, to better delineate an anatomic structure without obtaining additional images of the patient, and to create three-dimensional (3-D) imaging. <sup>9 Kalender W.A., Seissler W., Klotz E. , e al. Spiral volumetric CT with single-breath-hold technique, continuous transport, and continuous scanner rotation Radiology 1990 ;  176 : 181-183

Cliccare qui per andare alla sezione Riferimenti, 19 Zeman R.K., Baron R.L., Jeffrey R.B. , e al. Helical body CT: Evolution of scanning protocols AJR Am J Roentgenol 1998 ;  170 : 1427-1438

Cliccare qui per andare alla sezione Riferimenti</sup>

Three-dimensional reconstruction of helical CT images has become a popular and useful imaging tool, especially for neuroradiologic and vascular imaging. <sup>1 Dillon E.H., van Leeuwen M.S., Fernandez M.A. , e al. Spiral CT angiography AJR Am J Roentgenol 1993 ;  160 : 1273-1278

Cliccare qui per andare alla sezione Riferimenti, 6 Heiken J.P., Brink J.A., Vannier M.W. , e al. Spiral (helical) CT Radiology 1993 ;  189 : 647-656

Cliccare qui per andare alla sezione Riferimenti, 15 Napel S., Marks M.P., Rubin G.D. , e al. CT angiography with spiral CT and maximum intensity projection Radiology 1992 ;  185 : 607-610

Cliccare qui per andare alla sezione Riferimenti</sup> Because of the continuous data available from a single scan of a patient's body, the CT data can be reprocessed from a two-dimensional radiographic image into a 3-D image. Various programs have been created to rapidly perform 3-D reconstruction. Many of these programs are readily available on any commercial helical CT scanner.

Commercially available programs have been designed to automatically create a 3-D tracheobronchial tree model from CT scan images of the thorax. <sup>2 Ferretti G.R., Vining D.J., Knoplioch J. , e al. Tracheobronchial tree: Three-dimensional spiral CT with bronchoscopic perspective J Comput Assist Tomogr 1996 ;  20 : 777-781  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 7 Higgins W.E., Ramaswamy K., Swift R.D. , e al. Virtual bronchoscopy for three-dimensional pulmonary image assessment: State of the art and future needs Radiographics 1998 ;  18 : 761-778

Cliccare qui per andare alla sezione Riferimenti, 8 Hopper K.D., Iyriboz T.A., Mahraj R.P. , e al. CT bronchoscopy: Optimization of imaging parameters Radiology 1998 ;  209 : 872-877

Cliccare qui per andare alla sezione Riferimenti, 13 McAdams H.P., Palmer S.M., Erasmus J.J. , e al. Bronchial anastomotic complications in lung transplant recipients: Virtual bronchoscopy for noninvasive assessment Radiology 1998 ;  209 : 689-695

Cliccare qui per andare alla sezione Riferimenti</sup> These programs also enable the viewer to navigate through the inside of the tracheobronchial tree as if in a simulated or virtual bronchoscopy (VB). This technology has the potential to revolutionize the diagnostic imaging of diseases of the airways and adjacent to the airways (e.g., mediastinal masses). This article discusses how VB images are generated, the feasibility of VB in the clinical setting today, and what future directions radiology and medicine can take with this new, noninvasive imaging tool.