OBJECTIVETo analyze the images from the segmenting CT in the space of nasal endoscope and to observe the benefits in applying the method in endoscopic sinus surgery.

METHODSFive patients with inverted papilloma and ten patients with chronic rhinosinusitis were enrolled. The images from the coronal CT were put in the ideal model of the nasal cavity, which had been designed by SketchUp software package, and the space of the model in the 0 degree rod-lens telescope was simulated and observed according to definite elevation angle between the endoscope and bottom of nasal cavity and the distance of the endoscope entering the nasal cavity. The surgical plan was designed and compared with the models of the intraoperative corresponding vision.

RESULTSThe anatomical form of the images from the coronal CT and the directions of the space in the visual field of the endoscope were correlative with the elevation angle between the endoscope and bottom of nasal cavity and the distance of the endoscope entering the nasal cavity. Based on the elevation angle and the entering distance of the endoscope, the images from the CT scan in the space of nasal endoscope were analysed according to the order, which were consistent with the findings in the intraoperative corresponding vision, providing the accurate directions of the space for the endoscopic sinus surgery.

CONCLUSIONSThe changes of the images of the CT scan in the space of the endoscope were consistent with the perspective law. To know the perspective law could grasp the directions of the space in the visual field of the endoscope and ensure the safety of the endoscopic surgery. The method was simple and feasible. The benefits of this technique were confirmed by clinician.