[Geometric modeling and virtual endoscopy of the laryngo-tracheal lumen from computerized tomography images: initial applications to laryngo-tracheal pathology in the child].

Endoscopy is an essential stage in the management of laryngo-tracheal disorders in the infant, but remains a difficult procedure. CT scanning is used to confirm the abnormality and to estimate the degree to which the airway is compromised. The authors describe virtual endoscopy of the larynx and trachea based on a mathematical model, itself constructed from CT images. This work is based on a methodology developed at the Hôpital de la Timone for modelling the aorta. By applying this methodology to the study of laryngo-tracheal disorders, it is possible to establish the relevant pre-treatment measurements (length, diameter, degree of narrowing). This preliminary study has been carried out in 8 cases, in parallel with their clinical treatment. It has allowed us to single out the 3 typical examples which are presented in detail, and to show the advantages of this new approach: immediate and precise measurements, presentation which it is not possible to achieve with conventional techniques of 3-dimensional imaging, and demonstration of the degree of encroachment of the externe stenoses. When taken as part of the management of the patient, this technique complements the findings of real endoscopy, or replaces them, thus reducing the costs of hospital admission and the risks inherent in this procedure.